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Three-Year Outcome of Children Exposed Prenatally to Drugs
Three-Year Outcome of Children Exposed Prenatally to Drugs DAN R. GRIFFITH, PH.D., SCOTTD.AZUMA, PH.D., AND IRA]. CHASNOFF, M.D.
ABSTRACT Objective: To evaluate the 3-year behavioral and developmental outcome of children prenatally exposed to maternal
substances of abuse. Method: Ninety-three children exposed prenatally to cocaine and other drugs taken by the mother during pregnancy (Group 1), 24 polydrug/noncocaine exposed children (Group 2), and 25 nonexposed children (Group 3) were evaluated at 3 years of age as part of a longitudinal prospective study of the impact of intrauterine substance exposure on long-term outcome. The Stanford-Binet Intelligence Scale: Fourth Edition(SBIS) was administered by examiners blinded to the exposure background of the children, and a pediatrician performed a complete medical evaluation on all the children. The children's primary caregiver completed the Achenbach Child Behavior Checklist. Stepwise multiple regression procedures were used to determine the factors that best predicted 3-year growth, intelligence, and behavior. Results: Groups 1 and 2 differed from Group 3 on head circumference. Group 1 scored lower than Group 3 on SBIS Verbal Reasoning. Group 2 scored Slower than Group 3 on SBIS AbstracWisual Reasoning, Cocaine exposure predicted poor verbal reasoning. Marijuana exposure predicted poor abstract/visual reasoning. Examiner rating predicted intellectual outcome and caregiver ratings. Caregivers rated exposed children as more aggressive than nonexposed. Conclusion: Contrary to information in the popular media, not all substance-exposed children suffer the same poor prognosis. In fact, generalizations about the fate of drug-exposed children must await additional research into the outcome of the broader population of drug-exposed children, examining the roles of maternal and environmental factors across a variety of geographic locations and socioeconomic levels. J. Am. Acad. Child Ado/esc. Psychiatry, 1994,33,1:20-27. Key Words: cocaine, marijuana, alcohol, intelligence, behavior
Substance abuse during pregnancy has become a national concern. A recent estimate based on the National Institute on Drug Abuse Household Surveys of 1988 and 1990 indicates that each year 554,400 to 739,200 infants may be exposed in utero to one or more illicit drugs (Comby and Shiono, 1991). Such estimates, however, fail to consider the numbers of infants exposed to cigarettes and alcohol. The media is rife with stories concerning the fate of "crack" babies. The majority of these stories, however, are based on anecdotal information and overgeneralization of worst-case scenarios. The media coverage not only has created a negative stereotype of children exposed to cocaine but also has obscured the fact that
Accepted May 12, 1993. From The National Association for Perinatal Addiction Research and Education, Chicago, II. Supported byagrantfrom theNationallnstitute on DrugAbuse(DA04103). Correspondence to Dr. Chasnoff, NationalAssociation for Perinatal Addiction, Research and Education, 200 North Michigan Avenue, Suite 300, Chicago, IL 60611, (312)329-2512. 0890-8567/94/3301-0020$03.00/0©1994 by the American Academy of Child and Adolescent Psychiatry.
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the majority of children exposed to cocaine are exposed to other drugs as well. To date little research has been done to document the relative impact that different drugs either singly or in combination may have on the long-term development of children. Streissguth et al. (1989) examined the effects of prenatal exposure to alcohol and/or tobacco on IQ scores. They found a significant negative relationship between alcohol consumption during pregnancy by white, middle-class women and the IQ scores of their offspring at age 4 years. This relationship held after controlling for various prenatal and postnatal confounding variables. No such relationship with IQ scores existed for tobacco. Although not a focus of the Streissguth et al. study, marijuana, heroin, methadone, and other illicit drugs were used by some of the women in the sample. None of the illicit drugs were related to 4-year IQ scores. Fried and Watkinson (1990) examined the effects of prenatal exposure to marijuana, tobacco, and/or alcohol on developmental outcome at 36 and 48 months of age. In their predominately white, middleclass sample, Fried and Watkinson found cigarette
J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:1, JANUARY 1994
3-YEAR OUTCOME OF DRUG-EXPOSED CHILDREN
smoking to be related to poorer language development and cognitive functioning at both 36 and 48 months of age. Alcohol exposure was related to decreased cognitive abilities at 36 months but not 48 months of age. Marijuana exposure was not related to cognitive abilities at 36 months but by 48 months was associated with lower scores in the verbal and memory domains. To date only one study (Chasnoff et al., 1992) has examined the effects of prenatal cocaine or cocaine/ polydrug exposure on the development of infants and toddlers through 2 years of age. The present study represents a continuation of that study and presents the first information from a prospective longitudinal study on the effects of cocaine relative to other developmental risk factors through 3 years of age. METHOD Since April 1986 the National Association for Perinatal Addiction Research and Education (NAPARE)has followed the developmental progress of more than 300 infants and children exposed prenatally to drugs and alcohol. As part of a research project funded by the National Institute on Drug Abuse, drug- and alcohol-using women were enrolled in prenatal care and subsequent pediatric and developmental follow-up of their children. The present study is an examination of the 3-year outcome of 93 children born to women whose primary drug of abuse during pregnancy was cocaine. This group represents all cocaine-using women in the sample who had no evidence of concomitant opiate use; however, the majority of these women were using additional nonopiate substances: marijuana, alcohol, and/or tobacco. Twenty-four children enrolled in the same follow-up program who were prenatally exposed to various" combinations of marijuana, alcohol, and opiates but no cocaine J (Group 2) were evaluated as a comparison group. All drug-using women in both groups were enrolled by 15 weeks of pregnancy and received intensive obstetric and psychotherapeutic intervention through the remainder of pregnancy. The goal of the therapeutic interve~tion was to bring the women to abstinence. A prospectively ascertained group of 25 children with no history or evidence of prenatal exposure to alcohol or illicit drugs (Group 3) was evaluated to serve as a control group. These children were born to women", from the same urban neighborhoods and similar socioeconomic) backgrounds as the research groups. The majority of the children from all three groups were from lower socioeconomic backgrounds. Approximately 80% of the families across groups were on public ~sistanc~. All children in al~ three groups received referral to early intervention programs, physical therapy, occupational therapy, and/ or speech therapy when delays or developmental difficulties were uncovered. Informed consent was obtained from women in all three groups as approved by the Institutional Review Board of the State of Illinois. On admission to the program, a complete obstetric ~d drug-use history was obtained from all women. Urine toxicological analyses through Enzyme Multiplied Immunoassay Technique (EMIT) screening were performed on all women in Groups 1 and 2: To:acologic:J analysiswas performed for the following substances: mcotme, barbiturates, cocaine and its metabolites, opiates, benzodiazepines, propoxyphene, phencyclidine, amphetamines, alcohol,
and marijuana. All positive EMIT screens were confirmed by gas chromatography/mass spectrometry. All women in Groups 1 and 2 had random toxicological analyses of urines throughout pregnancy, and current substance use history was reviewed at all prenatal and postnatal visits for all three groups. As part of the longitudinal follow-up, all children were seen between the ages of 2 years, 11 months, 16 days and 3 years, 3 months, 15 days in a special research clinic by physicians and psychologists blinded to the children's prenatal history. Weight, heel to crown length, and fronro-occipital head circumferences were collected by the pediatrician. Psychologists administered the S~aI3f~r4-~ Intelligence Scale: 4th edition (Thorndike et al., f984) (SBIS). Test-taking behavior of the children was evaluated via the five-point rating scales provided by the SBIS. For the purpose of the present study, children were considered to score high on a given problem behavior if they received a score of four or five. A summative attention scale score was created from these SBIS ratings by combining the scores for distractibility, activity level, gives up easily, and prefers only easy tasks. These items were judged by the authors to assess the ability of children to sustain attention on the more challenging test items. The Child Behavior Checklist (Achenbach, 1988) (CBCL) was completed by the p~ mary caregiver. Information was collected from all three groups concerning whether children were living with their natural mother and/or whether anyone in the household continued to use drugs. For those children not living with their natural mothers, information on the type and number of foster placements was collected. Growth and behavioral information were statistically analyzed in two phases. The first phase analyzed the data for prenatal exposure effects and gender effects. Weight, length, head circumference, Stanford Binet standard age scores (SAS) and CBCL measures were each analyzed in a 2 x 3 factorial design with drug group and gender as independent variables. Significant findings were additionally analyzed with the Student Newman-Keuls post-hoc procedure. The purpose of the second phase was to determine the relationship between drug use, growth measures, intellectual outcomes, and measures of behavior. Pearsons correlations were computed to analyze bivariate relationships among interval level variables. Relationships between nominal and ordinal variableswere estimated with a X2 test for independence. Stepwise multiple regression procedures were used to determine the factors that best predicted 3-year growth, intelligence, and behavior. Type of drug exposure (cocaine, marijuana, alcohol, opiates, tobacco), head circumference, CBCL findings, and ratings from the SBIS were chosen a priori as the most salient predictors of cognitive functioning on the SBIS. Note that the set of drug variables included both individual and drug interaction variables so as to account for the predictability of drug interactions. Drug exposure, head circumference, and SBIS summative rating scores were tested as predictors of aggressive, destructive, and externalization domains on the CBCL. A final regression model was hypothesized with the SBIS summative attention scale as the dependent variable. This model included drug exposure, head circumference, and CBCL findings. A summary of these models is presented in Table 1.
RESULTS
Mean maternal agesfor Group 1 (26.8 years), Group 2 (27.0 years) and Group 3 (25.3) were similar by \
J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:1, JANUARY 1994
21
GRIFFITH ETAL.
TABLE 1 3-Year Outcome Regression Models Dependent Variables Stanford-Binet Intelligence Scale (SBIS) Verbal reasoning Abstract/visual reasoning
Child Behavior Checklist (CBCL) Outcomes Aggressive Destructive Externalization
SBIS Summative Attention Scale
Independent Variables
Cocaine Marijuana Alcohol Tobacco Opiates Head circumference Cocaine/marijuana Cocaine/alcohol Cocaine/marijuana/alcohol Marijuana/alcohol Activity Scale CBCL aggressive CBCL destructive CBCL externalizat ion
Cocaine Marijuana Alcohol Tobacco Opiates Head circumference Cocaine/marijuana Cocaine/alcohol Cocaine/marijuana/alcohol Marijuana/alcohol Activity Scale Cocaine Marijuana Alcohol Tobacco Opiates Head circumference Cocaine/marijuana Cocaine/alcohol Cocaine/marijuana/alcohol Marijuana/alcohol
analysis of variance. All groups had similar distributions of male and female children: 47 boys and 46 girls in Group 1, 13 boys and 11 girls in Group 2, and 12 boys and 13 girls in Group 3. There were no significant differences across groups via X2 analysis for racial composition : 18% white, 74% black, 6% Hispanic, and 2% other in Group 1; 30% white, 60% black, and 10% Hispanic in Group 2; and 9% white, 82% black, and 9% Hispanic in Group 3. Among the cocaine/polydrug exposed children 51 (55%) were prenatally exposed to marijuana, 58 (62%) to alcohol, and 78 (84%) to tobacco cigarettes. Among
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J.
the polydrug/noncocaine exposed children 10 (42%) were prenatally exposed to marijuana, 9 (38%) to alcohol, 7 (29%) to opiates, 9 (38%) to cigarettes, and 3 (13%) to phencyclidine. Among the children in the control group 5 (20%) were prenatally exposed to tobacco cigarettes. There was no history or evidence of prenatal exposute to illicit substances or alcohol among the children in the control group. All three groups of children were similar with regard to mean length and weight adjusted for conceptual age in those children born at less than 38 weeks . .gestational age (Table 2). Each drug-exposed group, ( however, had a significantly smaller mean head circumL ference at 3 years of age than did the control group TP < .05). Stepwise regression analyses were performed to evaluate the degree to which exposure to drugs (cocaine, alcohol, marijuana, opiates, and tobacco) either singly or in combinations predicted head sizes below the tenth percentile and below the fifth percentile. None of the individual drugs or drug interactions were predictive of small head size. In addition to smaller mean head size, each of the drug-exposed groups displayed significant trends indicating greater numbers of children falling below the tenth and fifth percentiles for head circumference. Forty percent of the cocaine/polydrug exposed group and 42% of the polydrug/noncocaine exposed group as compared to 15% of the nonexposed control group had head sizes below the tenth percentile (p :::; .10). Children with head sizes below the fifth percentile comprised 20% ofthe cocaine/polydrug exposed group, 12% of the polydrug/noncocaine exposed group, and 0% of the control group (X2, p s .10). Mean standard age scores (SAS) on the SBIS are displayed in Table 3. The cocaine/polydrug group [~~ored significantly lower than did the control group ~verbal reasoning (p < .05). The polydrug, noncocaine group scored significantly lower than did the control group on abstract/visual reasoning (p < .05). No significant differences among the groups were noted on mean SAS scores for the overall test, shortterm memory, or quantitative reasoning. Chi square analyses were conducted on the number of children in each group falling a standard deviation or more below the normative sample means for the SBIS. No differences were found among the groups for the overall test or any of the four subareas of the SBIS.Within groups both drug-exposed groups showed
AM . ACAD . CHILD ADOLESC . PSYCHIATRY, 33:2, FEBRUARY 19 94
3-YEAR OUTCOME OF DRUG-EXPOSED CHILDREN
TABLE 2 Growth Parameters by Group at 3 Years of Af;e Cocaine/Polydrug (N = 68)
2220.2 4.1 1.5
14884.0 95.7 49.2*
(N = 16)
SD
SD Weight (grams) Length (centimeters) Head Circumference (centimeters)
Controls
Polydrug/Noncocaine (N = 18)
15155.9 94.8 49.1*
1978.5 5.4 1.6
SD 15593.7 97.0 50.3
2471.3 4.3 2.1
*Significant difference from Group 3 (analysis of variance, Neuman-Keuls, p < .05).
TABLE 3 Mean 3-Year Stanford-Binet Standard Af;e Scores by Group Cocaine/Polydrug (N = 92)
Overall test Verbal reasoning Abstract/visual reasoning Quantitative reasoning Short-term memory
Polydrug/Noncocaine (N = 23)
x
SD
x
94.4 89.3* 93.5 99.9 99.3
9.4 8.2 11.9 10.1 8.5
93.2 90.3 90.1* 98.9 99.9
SD 9.3 10.9 9.6 10.5 9.4
Controls (N = 25) SD
x
98.5 95.2 98.2 102.4 101.7
12.8 11.8 13.9 10.9 12.9
*Significant difference from control group (analysis of variance, Neuman-Keuls, p < .05).
delays most often in the areas of verbal and abstract visual reasoning. Analyses of caregiving environments for the three groups indicated that all of the controls were living in nondrug-using households with their biologic mothers. Within the cocaine/polydrug group, 28 (30%) had lived since birth with their biologic mother who continued to use drugs, 26 (28%) had lived since birth with biologic mothers, who had achieved a drug- and alcohol-free status within 1 year after their children's births, and 23 (25%) had lived since shortly after birth with foster relatives in a drug- and alcohol-free environment. The remaining 16 children from Group 1 had been in foster nonrelative and/or multiple placements since birth. Among the polydrug/noncocaine exposed children, 12 (50%) had lived since birth with biologic mothers who continued to use drugs, 7 (29%) had lived since birth with drug- and alcohol-free biologic mothers, and 5 (21%) had lived with foster relatives in drug- and alcohol-free homes. Exposure to tobacco cigarettes postnatally continued in patterns similar to the prenatal exposure to tobacco. Analysis of the effects of caregiving environment on SBIS outcomes for cocaine/polydrug children are summarized in Table 4. Those Group 1 children who were continuing to live in a drug-using household were
J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:1, JANUARY 1994
TABLE 4 Developmental Outcome by Caregiving Environment for Cocaine/Polydrug Group Living with Drug-Using Biological Mother
N = 28 Living with drug-free biological mother N = 26 living with drug-free relative N = 23 % score S 84 on overall Stanford-Binet 25 4 13 % scoring S 84 on Sranford-Binet Verbal Reasoning 43 19 13 % scoring S 84 on Stanford-Binet Abstract/Visual Reasoning 32 12 9
*x2 (p ::;; .025). delayed by a standard deviation or more significantly more often on the verbal reasoning portion of the SBIS than were those living in drug-free environments. There were no significant differences acrosscaregiving environments on the SBIS for Group 2. Table 5 presents a summary of the blinded examiner ratings of test-taking behavior on the SBIS. The two drug-exposed groups were significantly more likely to show a preference for easy tasks (p < .05). No other group differences were noted for ratings of test-taking behaviors including the summative attention score. Results for the CBCL are presented in Table 6. Children were considered to be displaying problematic behavior if their T score on a given scale was greater than or equal to 60. Both drug exposed groups, as 23
GRIFFITH ET AL.
TABLE 5 Examiner Ratings of 3-Year Behavior on me Srandford-Binet Intelligence Scale Cocaine/Polydrug N Scoring
Distractibility Activity level Gives up easily Seeks to terminate Prefers easy tasks" Poor articulation Poor sound discrimination
46 25 48 38 37 36 20
~
4
Polydrug/Noncocaine %
54 29 56 44 44 42 23
N Scoring
~
4
14 12 14 16 11
12 9
%
60 54 60 69 48 54 39
Controls N Scoring 11
9 11 10 5 15 5
~
4
%
44 36 44 40 20 60 20
*X2 (p < .05)
compared with the control group, were rated by caregivers as displaying more destructive behavior (p < .05). The cocaine/polydrug group showed significantly greater numbers of children demonstrating aggressive behavior when compared with the control group. In addition, both drug groups had significantly greater numbers of children expressing externalizing behavior when compared with the control group. Gender differences were tested for each of the ourcome measures via factorial analyses. No gender differences were found for any of the SBIS intellectual outcome measures. On the SBIS behavioral ratings boys were found to be more active (p ~ .05) and to give up more easily (p ~ .05) when compared with girls. On the CBCL, male children tended to be rated as more destructive than females (p ~ .05). No other gender differences were found on the CBCL. Regression Results
The results from the stepwise regression analyses of intellectual and behavioral outcomes are presented in Table 7. The SBIS summative attention rating and (Cocaine exposure were found to be significant pre"dictors of lower SBIS Verbal Reasoning scores. The ' SBIS summative attention ratings, marijuana exposure, and the interaction of cocaine, marijuana , and alcohol exposure were found to be significant predictors of lower SBIS Abstract/Visual Reasoning scores. For the CBCL behavioral domains, the SBIS summarive attention rating and alcohol were found to be significant predictors of aggressive behaviors. Only the summative attention scale was noted to predict destructive behavior. Summative attention ratings and cocaine exposure were predictive of externalization.
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None of the entered variables were significant predictors of the SBIS summative attention rating. DISCUSSION
In some respects the findings of the present study parallel those of the authors ' study of drug-exposed children through age 2 years (Chasnoff et al., 1992). That research indicated drug-exposed children , whether cocaine/polydrug exposed or polydrug/noncocaine exposed, continued through 2 years to display smaller head sizes as a group than did nonexposed children . The 2-year study additionally demonstrated that there were no differences between the two drug-exposed groups and the control group by age 2 years on a global measure of cognitive development such as the Bayley Mental Index. A final major finding of the 2-year study was the significant relationship between small head size and cocaine exposure. Findings of the present study, however, indicated that neither cocaine nor any other drug was predictive of small head size at 3 years of age. Each drug group , however, displayed smaller mean head sizes than did the control group. Although the .differences were not statistically significant, each drug group as compared with the control group had greater numbers of children falling below the tenth and the fifth percentiles for head circumference. The tendency for drug-exposed children to be born with smaller heads may be a major marker for predicting poor longterm developmental outcome (Eckerman et al. 1985, Emhart et al., 1987, Gross et al., 1983, and Lifschitz et al., 1985). The lack of catch-up growth in head size for those drug-exposed children with subnormal head sizes in the present study provides a stronger
J. AM . ACAD . CHILD ADOLESC . PSYCHIATRY, 33,1, JANUARY 1994
3-YEAR OUTCOME OF DRUG-EXPOSED CHILDREN
Problematic Behavior (T Score
~
TABLE 6 60) by Group on the Child Behavior Checklist
Cocaine/Polydrug (N = 55) N(T)
Social withdrawal Depressed Sleep problems Somatic problems Aggressive* Destructive* Internalizing Externalizing*
~
Polydrug/Noncocaine (N = 20)
%
60
23 18 20 22 18 27 18 20
13 10 11 12
10 15 10 11
N(T)
2 3 5 4 4 3 2 4
~
60
% 10 15 25 20 20 15 10 20
Controls (N = 17) N(T)
1 I
1 2 0 0 1 0
~
60
%
5 5 5 12
o o 6
o
*X2 (p :5 .05). TABLE 7 Regression Analyses Variable
B
<
P
Variance
Variable reasoning SBIS' Summative Attention Scale Cocaine
-.43 -.29
.000 .010
.19 .09
Total equation: R 2 = .28 Abstract Reasoning SBIS Summative Attention Scale Marijuana Cocaine/Marijuana!Alcohol
-.43 -.68 .40
.000 .000 .020
.26 .13 .05
SBIS Summative Attention Scale Alcohol
.30 .22
.001 .050
.09 .05
Total equation: R 2 = .14 CBCL destructive SBIS Summative Attention Scale
.25
.040
.04
Total equation: R 2 = .06 CBCL external SBIS Summative Attention Scale Cocaine
.25 .23
.030 .040
.08 .05
Total equation: R 2 = .44
CBCU Aggressive
Total equation: R 2 = .13 'SBIS = Stanford-Binet Intelligence Scale. bCBCL = Child Behavior Checklist.
indicator of potential problems. Hack et al. (1991), for example, found subnormal head size at 8 months of age to be predictive of poorer verbal and performance IQ scores at 8 years of age. The fact that subnormal head size at age 3 years did not predict intellectual performance at age 3 may
J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:1, JANUARY 1994
be due in part to the types of cognitive abilities one can assess in 3 year olds. It may be that the underlying problems represented by subnormal head size will be manifested in older children as they attempt more complex forms of learning and reasoning. Previous research into the developmental course of brain insult indicates that deficits often are delayed until later periods of development (Almli and Finger, 1984; Boll and Barth, 1981; and Tramontana and Hooper, 1988). Similar to the authors' 2-year study, there were no significant differences among the two drug groups and the control group on global measures of intellectual development. Although there were no group differences on the overall scores for the SBIS, the cocaine/polydrug group received significantly lower scores on verbal reasoning tasks and the polydrug/noncocaine group scored significantly lower on abstract/visual reasoning. The appearance of differences in intellectual performance at age 3 years between each of the drug groups and the control group may be in part because of the direct biologic effects of various drugs either singly or in combination. Results of the regression analysesfrom the present study support this hypothesis. Cocaine, for example, was shown to have a significant negative impact on verbal reasoning scores independent of the child's head circumference, other drugs of exposure, or the child's behavior as rated by examiner or caregiver.Marijuana and the combination of marijuana, cocaine, and alcohol were predictive of poor performance on abstract/visual reasoning when various confounding variables were partialed out. The group differences on specific areas of the SBIS at age 3 years represent the first research evidence
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GRIFFITH ET AL.
linking prenatal cocaine exposure to long-term developmental outcome. Alcohol (Streissguth et al., 1989) and marijuana (Fried and Watkinson, 1990) have been linked to poor intellectual outcome in 4 year olds, but no interactive effects among marijuana, alcohol, and cocaine have been reported. As has been suggested by Chasnoff et al. (I 992) and Fried and Watkinson (1990) the emergence of drug-related deficits in older drug-exposed children . may represent the subtle effects that prenatal substance exposure has on the complex intellectual skills that develop throughout childhood. The significant findings in the present study relating drug exposure to lower scores on intellectual measures must be interpreted with extreme caution. It is important to note that in the present sample cocaine accounted for only 9% of the variance in verbal reasoning, marijuana accounted for 13% of the variance in abstract/visual reasoning, and the combination of cocaine, marijuana, and alcohol accounted for 5% of the variance in abstract/visual reasoning. Therefore to evaluate successfully the intellectual outcome of drug-exposed children, one must consider the multitude of other factors that contribute to the variance in intellectual outcome . The obvious factors that must be explored in greater detail are those differentiating the drug-using environment from the drugfree environment. In the present study, for example, children were much more likely to display problems in verbal reasoning if they were being raised in a home where drugs continued to be used. It is important to note that the drug-free homes in the present study represented permanent, stable placements for the children. Differences in outcome measures may not be as pronounced when comparing children raised in a stable yet drug-using environment with children raised in multiple drug-free placements. In addition to the effects of multiple placements, one has to consider the adaptive level of functioning within each placement. Previous research by Jeremy and Bernstein (1984) demonstrated that the best predictors of developmental outcome for methadone-exposed children and nonexposed children were the psychological resources of the mother. Future studies from the present authors will examine the ongoing intellectual development of drug-exposed children as affected by differences in personality, intelligence, social support systems, and parenting skills
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between women who continue to use drugs versus those who have been able to quit. Research has yet to determine the roles of maternal and environmental factors as predictors of behavioral differences between drug-exposed children and nonexposed children. For the present, study exposure to drugs was linked to problem behaviors in 3 year olds. Examiner ratings indicated greater difficulty in sustaining attention during difficult tasks for the two drug groups as compared with the control group . Caregiver reports rated both drug- exposed groups as more aggressive than the controls. Caregivers rated the cocaine/polydrug-exposed children as more destructive than the drug-free controls. Whether these behaviors will continue as the child grows older is unknown. Analyses of predictive factors of problem behaviors indicated that prenatal alcohol exposure was predictive of aggression (accounting for 5% of the variance). Intrauterine cocaine exposure was predictive of externality, which represents behaviors characterized as aggressive and/or destructive. Cocaine, however, accounted for only 5% of the variance in externality. Perhaps the most significant finding from the present study was that among all variables considered the blinded examiners' ratings via the summative attention scale provided the strongest predictor of poor verbal reasoning, poor nonverbal reasoning, aggression, destructiveness, and externality. These findings highlight the importance of using the observations and judgment of trained clinicians as sources of information concerning the overall functioning of the child. Examiner clinical judgment will be particularly important in documenting any subtle effects that prenatal substance exposure may have on children's behavioral and intellectual functioning. The findings of the present study represent a bestcase scenario of the developmental and behavioral outcome of children exposed prenatally to drugs. The majority of the drug-exposed children in the present study scored within the average ranges for intellectual abilities and displayed no significant behavioral problems. These children, however, represent a select sample of drug-exposed children for whom major prenatal risk factors were reduced and early, and continuous medical and developmental assessment, diagnosis, and intervention were provided. Contrary to information in the popular media, not all substance-exposed children suffer the same poor
J . AM. ACAD . CHILD ADOLES C. PSYCHIATRY, 33:1, JANUARY 1994
3-YEAR OUTCOME OF DRUG-EXPOSED CHILDREN
prognosis. In fact, generalizations about the fate of drug-exposed children must await additional research into the outcome of the broader population of drugexposed children. Future research must examine the roles of maternal and environmental factors across a variety ofgeographic locations and socioeconomic levels in predicting differences between drug-exposed children and nonexposed children. No research is available on the long-term social, emotional, behavioral, and intellectual outcomes of children exposed to drugs in multirisk environments in the absence of intervention services. Lack of prenatal care, poor prenatal nutrition, abuse, neglect, multiple placements, poor postnatal nutrition, and poor medical care must all be considered in evaluating the outcome of drug-exposed children .
REFERENCES Achenbach TM (1988), ChildBehavior Checklistfor Ages 2-3. Burlington, VT: University of Vermont. Almli CR, Finger S (1984), Early Brain Damage. Orlando, FL: Academic Pressplease cite this reference in text or delete here.
J . AM . ACAD. CHILD ADOLESC . PSYCHIATRY, 33:1, JANUARY 1994
Boll T] , Barth]T (1981), Neuropsychology of brain damage in children. In: Handbook of Clinical Neuropsychology, eds, SB Filskov, T] Boll. New York: Wiley, pp 418-452 Chasnoff I], Griffith DR, Freier C, Murray] (1992), Cocaine/polydrug use in pregnancy: twO year follow-up. Pediatr 89:284-289 Eckerman CO , Lynne AS, Gross S] (1985), Different developmental courses for very-low birthweight infants. Developmental Psychology 21:813-8 27 Emhart CB, Marler MR, Morrow-Tlucak M (1987), Head size and cognitive development in the early preschool years. Psycho' Reports 61:103-106 Fried PA, Watkinson B (1990), 36- and 48-month neurobehavioral followup of children prenatally exposed to marijuana, cigarettes, and alcohol.
J Dev Behav Pediatr 11 :49-58 Gomby OS, Shiono PH (1991), Estimating the number of substanceexposed infants. Future Child 1:17-25 Gross S], Oehler ]M, Eckreman CO (1983), Head growth and development outcome in very low birthweight infants. Pediatrics 71:70-75 Hack M, Breslan N , Weissman B, Aram 0 , Klein N, Borawski E (1991), Effects of very low birthweight and subnormal head size on cognitive abilities at school age. N EnglJ Med 325:231-237 Jeremy R, Bernstein VJ (1984), Dyads at risk: methadone-maintained women and their four month old infants. Child Dev 55:1141-1154 Lifschirz MH , Wilson GS, Smith EO , Desmond MM (1985), Factors affecting head growth and intellectual function in children of drug addicts. Pediatrics 75: 269-274 Streissguth AP, Barr HM , Sampson PO , Darby BL, Mart in DC (1989), IQ at age 4 in relation to maternal alcohol use and smoking during pregnancy. Developmental Psychology 25:3-11 Thorndike RL, Hagen EP, Sattler]M (1984), TheStanford-Bina Intelligence Scale: Fourth Edition, Chicago: Riverside Publishing Tramontana MG, Hooper SR (1988), Assessment Issues in ChildNeuropsycbology. New York: Plenum Press
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ABSTRACT Objective: To evaluate the 3-year behavioral and developmental outcome of children prenatally exposed to maternal
substances of abuse. Method: Ninety-three children exposed prenatally to cocaine and other drugs taken by the mother during pregnancy (Group 1), 24 polydrug/noncocaine exposed children (Group 2), and 25 nonexposed children (Group 3) were evaluated at 3 years of age as part of a longitudinal prospective study of the impact of intrauterine substance exposure on long-term outcome. The Stanford-Binet Intelligence Scale: Fourth Edition(SBIS) was administered by examiners blinded to the exposure background of the children, and a pediatrician performed a complete medical evaluation on all the children. The children's primary caregiver completed the Achenbach Child Behavior Checklist. Stepwise multiple regression procedures were used to determine the factors that best predicted 3-year growth, intelligence, and behavior. Results: Groups 1 and 2 differed from Group 3 on head circumference. Group 1 scored lower than Group 3 on SBIS Verbal Reasoning. Group 2 scored Slower than Group 3 on SBIS AbstracWisual Reasoning, Cocaine exposure predicted poor verbal reasoning. Marijuana exposure predicted poor abstract/visual reasoning. Examiner rating predicted intellectual outcome and caregiver ratings. Caregivers rated exposed children as more aggressive than nonexposed. Conclusion: Contrary to information in the popular media, not all substance-exposed children suffer the same poor prognosis. In fact, generalizations about the fate of drug-exposed children must await additional research into the outcome of the broader population of drug-exposed children, examining the roles of maternal and environmental factors across a variety of geographic locations and socioeconomic levels. J. Am. Acad. Child Ado/esc. Psychiatry, 1994,33,1:20-27. Key Words: cocaine, marijuana, alcohol, intelligence, behavior
Substance abuse during pregnancy has become a national concern. A recent estimate based on the National Institute on Drug Abuse Household Surveys of 1988 and 1990 indicates that each year 554,400 to 739,200 infants may be exposed in utero to one or more illicit drugs (Comby and Shiono, 1991). Such estimates, however, fail to consider the numbers of infants exposed to cigarettes and alcohol. The media is rife with stories concerning the fate of "crack" babies. The majority of these stories, however, are based on anecdotal information and overgeneralization of worst-case scenarios. The media coverage not only has created a negative stereotype of children exposed to cocaine but also has obscured the fact that
Accepted May 12, 1993. From The National Association for Perinatal Addiction Research and Education, Chicago, II. Supported byagrantfrom theNationallnstitute on DrugAbuse(DA04103). Correspondence to Dr. Chasnoff, NationalAssociation for Perinatal Addiction, Research and Education, 200 North Michigan Avenue, Suite 300, Chicago, IL 60611, (312)329-2512. 0890-8567/94/3301-0020$03.00/0©1994 by the American Academy of Child and Adolescent Psychiatry.
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the majority of children exposed to cocaine are exposed to other drugs as well. To date little research has been done to document the relative impact that different drugs either singly or in combination may have on the long-term development of children. Streissguth et al. (1989) examined the effects of prenatal exposure to alcohol and/or tobacco on IQ scores. They found a significant negative relationship between alcohol consumption during pregnancy by white, middle-class women and the IQ scores of their offspring at age 4 years. This relationship held after controlling for various prenatal and postnatal confounding variables. No such relationship with IQ scores existed for tobacco. Although not a focus of the Streissguth et al. study, marijuana, heroin, methadone, and other illicit drugs were used by some of the women in the sample. None of the illicit drugs were related to 4-year IQ scores. Fried and Watkinson (1990) examined the effects of prenatal exposure to marijuana, tobacco, and/or alcohol on developmental outcome at 36 and 48 months of age. In their predominately white, middleclass sample, Fried and Watkinson found cigarette
J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:1, JANUARY 1994
3-YEAR OUTCOME OF DRUG-EXPOSED CHILDREN
smoking to be related to poorer language development and cognitive functioning at both 36 and 48 months of age. Alcohol exposure was related to decreased cognitive abilities at 36 months but not 48 months of age. Marijuana exposure was not related to cognitive abilities at 36 months but by 48 months was associated with lower scores in the verbal and memory domains. To date only one study (Chasnoff et al., 1992) has examined the effects of prenatal cocaine or cocaine/ polydrug exposure on the development of infants and toddlers through 2 years of age. The present study represents a continuation of that study and presents the first information from a prospective longitudinal study on the effects of cocaine relative to other developmental risk factors through 3 years of age. METHOD Since April 1986 the National Association for Perinatal Addiction Research and Education (NAPARE)has followed the developmental progress of more than 300 infants and children exposed prenatally to drugs and alcohol. As part of a research project funded by the National Institute on Drug Abuse, drug- and alcohol-using women were enrolled in prenatal care and subsequent pediatric and developmental follow-up of their children. The present study is an examination of the 3-year outcome of 93 children born to women whose primary drug of abuse during pregnancy was cocaine. This group represents all cocaine-using women in the sample who had no evidence of concomitant opiate use; however, the majority of these women were using additional nonopiate substances: marijuana, alcohol, and/or tobacco. Twenty-four children enrolled in the same follow-up program who were prenatally exposed to various" combinations of marijuana, alcohol, and opiates but no cocaine J (Group 2) were evaluated as a comparison group. All drug-using women in both groups were enrolled by 15 weeks of pregnancy and received intensive obstetric and psychotherapeutic intervention through the remainder of pregnancy. The goal of the therapeutic interve~tion was to bring the women to abstinence. A prospectively ascertained group of 25 children with no history or evidence of prenatal exposure to alcohol or illicit drugs (Group 3) was evaluated to serve as a control group. These children were born to women", from the same urban neighborhoods and similar socioeconomic) backgrounds as the research groups. The majority of the children from all three groups were from lower socioeconomic backgrounds. Approximately 80% of the families across groups were on public ~sistanc~. All children in al~ three groups received referral to early intervention programs, physical therapy, occupational therapy, and/ or speech therapy when delays or developmental difficulties were uncovered. Informed consent was obtained from women in all three groups as approved by the Institutional Review Board of the State of Illinois. On admission to the program, a complete obstetric ~d drug-use history was obtained from all women. Urine toxicological analyses through Enzyme Multiplied Immunoassay Technique (EMIT) screening were performed on all women in Groups 1 and 2: To:acologic:J analysiswas performed for the following substances: mcotme, barbiturates, cocaine and its metabolites, opiates, benzodiazepines, propoxyphene, phencyclidine, amphetamines, alcohol,
and marijuana. All positive EMIT screens were confirmed by gas chromatography/mass spectrometry. All women in Groups 1 and 2 had random toxicological analyses of urines throughout pregnancy, and current substance use history was reviewed at all prenatal and postnatal visits for all three groups. As part of the longitudinal follow-up, all children were seen between the ages of 2 years, 11 months, 16 days and 3 years, 3 months, 15 days in a special research clinic by physicians and psychologists blinded to the children's prenatal history. Weight, heel to crown length, and fronro-occipital head circumferences were collected by the pediatrician. Psychologists administered the S~aI3f~r4-~ Intelligence Scale: 4th edition (Thorndike et al., f984) (SBIS). Test-taking behavior of the children was evaluated via the five-point rating scales provided by the SBIS. For the purpose of the present study, children were considered to score high on a given problem behavior if they received a score of four or five. A summative attention scale score was created from these SBIS ratings by combining the scores for distractibility, activity level, gives up easily, and prefers only easy tasks. These items were judged by the authors to assess the ability of children to sustain attention on the more challenging test items. The Child Behavior Checklist (Achenbach, 1988) (CBCL) was completed by the p~ mary caregiver. Information was collected from all three groups concerning whether children were living with their natural mother and/or whether anyone in the household continued to use drugs. For those children not living with their natural mothers, information on the type and number of foster placements was collected. Growth and behavioral information were statistically analyzed in two phases. The first phase analyzed the data for prenatal exposure effects and gender effects. Weight, length, head circumference, Stanford Binet standard age scores (SAS) and CBCL measures were each analyzed in a 2 x 3 factorial design with drug group and gender as independent variables. Significant findings were additionally analyzed with the Student Newman-Keuls post-hoc procedure. The purpose of the second phase was to determine the relationship between drug use, growth measures, intellectual outcomes, and measures of behavior. Pearsons correlations were computed to analyze bivariate relationships among interval level variables. Relationships between nominal and ordinal variableswere estimated with a X2 test for independence. Stepwise multiple regression procedures were used to determine the factors that best predicted 3-year growth, intelligence, and behavior. Type of drug exposure (cocaine, marijuana, alcohol, opiates, tobacco), head circumference, CBCL findings, and ratings from the SBIS were chosen a priori as the most salient predictors of cognitive functioning on the SBIS. Note that the set of drug variables included both individual and drug interaction variables so as to account for the predictability of drug interactions. Drug exposure, head circumference, and SBIS summative rating scores were tested as predictors of aggressive, destructive, and externalization domains on the CBCL. A final regression model was hypothesized with the SBIS summative attention scale as the dependent variable. This model included drug exposure, head circumference, and CBCL findings. A summary of these models is presented in Table 1.
RESULTS
Mean maternal agesfor Group 1 (26.8 years), Group 2 (27.0 years) and Group 3 (25.3) were similar by \
J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:1, JANUARY 1994
21
GRIFFITH ETAL.
TABLE 1 3-Year Outcome Regression Models Dependent Variables Stanford-Binet Intelligence Scale (SBIS) Verbal reasoning Abstract/visual reasoning
Child Behavior Checklist (CBCL) Outcomes Aggressive Destructive Externalization
SBIS Summative Attention Scale
Independent Variables
Cocaine Marijuana Alcohol Tobacco Opiates Head circumference Cocaine/marijuana Cocaine/alcohol Cocaine/marijuana/alcohol Marijuana/alcohol Activity Scale CBCL aggressive CBCL destructive CBCL externalizat ion
Cocaine Marijuana Alcohol Tobacco Opiates Head circumference Cocaine/marijuana Cocaine/alcohol Cocaine/marijuana/alcohol Marijuana/alcohol Activity Scale Cocaine Marijuana Alcohol Tobacco Opiates Head circumference Cocaine/marijuana Cocaine/alcohol Cocaine/marijuana/alcohol Marijuana/alcohol
analysis of variance. All groups had similar distributions of male and female children: 47 boys and 46 girls in Group 1, 13 boys and 11 girls in Group 2, and 12 boys and 13 girls in Group 3. There were no significant differences across groups via X2 analysis for racial composition : 18% white, 74% black, 6% Hispanic, and 2% other in Group 1; 30% white, 60% black, and 10% Hispanic in Group 2; and 9% white, 82% black, and 9% Hispanic in Group 3. Among the cocaine/polydrug exposed children 51 (55%) were prenatally exposed to marijuana, 58 (62%) to alcohol, and 78 (84%) to tobacco cigarettes. Among
22
J.
the polydrug/noncocaine exposed children 10 (42%) were prenatally exposed to marijuana, 9 (38%) to alcohol, 7 (29%) to opiates, 9 (38%) to cigarettes, and 3 (13%) to phencyclidine. Among the children in the control group 5 (20%) were prenatally exposed to tobacco cigarettes. There was no history or evidence of prenatal exposute to illicit substances or alcohol among the children in the control group. All three groups of children were similar with regard to mean length and weight adjusted for conceptual age in those children born at less than 38 weeks . .gestational age (Table 2). Each drug-exposed group, ( however, had a significantly smaller mean head circumL ference at 3 years of age than did the control group TP < .05). Stepwise regression analyses were performed to evaluate the degree to which exposure to drugs (cocaine, alcohol, marijuana, opiates, and tobacco) either singly or in combinations predicted head sizes below the tenth percentile and below the fifth percentile. None of the individual drugs or drug interactions were predictive of small head size. In addition to smaller mean head size, each of the drug-exposed groups displayed significant trends indicating greater numbers of children falling below the tenth and fifth percentiles for head circumference. Forty percent of the cocaine/polydrug exposed group and 42% of the polydrug/noncocaine exposed group as compared to 15% of the nonexposed control group had head sizes below the tenth percentile (p :::; .10). Children with head sizes below the fifth percentile comprised 20% ofthe cocaine/polydrug exposed group, 12% of the polydrug/noncocaine exposed group, and 0% of the control group (X2, p s .10). Mean standard age scores (SAS) on the SBIS are displayed in Table 3. The cocaine/polydrug group [~~ored significantly lower than did the control group ~verbal reasoning (p < .05). The polydrug, noncocaine group scored significantly lower than did the control group on abstract/visual reasoning (p < .05). No significant differences among the groups were noted on mean SAS scores for the overall test, shortterm memory, or quantitative reasoning. Chi square analyses were conducted on the number of children in each group falling a standard deviation or more below the normative sample means for the SBIS. No differences were found among the groups for the overall test or any of the four subareas of the SBIS.Within groups both drug-exposed groups showed
AM . ACAD . CHILD ADOLESC . PSYCHIATRY, 33:2, FEBRUARY 19 94
3-YEAR OUTCOME OF DRUG-EXPOSED CHILDREN
TABLE 2 Growth Parameters by Group at 3 Years of Af;e Cocaine/Polydrug (N = 68)
2220.2 4.1 1.5
14884.0 95.7 49.2*
(N = 16)
SD
SD Weight (grams) Length (centimeters) Head Circumference (centimeters)
Controls
Polydrug/Noncocaine (N = 18)
15155.9 94.8 49.1*
1978.5 5.4 1.6
SD 15593.7 97.0 50.3
2471.3 4.3 2.1
*Significant difference from Group 3 (analysis of variance, Neuman-Keuls, p < .05).
TABLE 3 Mean 3-Year Stanford-Binet Standard Af;e Scores by Group Cocaine/Polydrug (N = 92)
Overall test Verbal reasoning Abstract/visual reasoning Quantitative reasoning Short-term memory
Polydrug/Noncocaine (N = 23)
x
SD
x
94.4 89.3* 93.5 99.9 99.3
9.4 8.2 11.9 10.1 8.5
93.2 90.3 90.1* 98.9 99.9
SD 9.3 10.9 9.6 10.5 9.4
Controls (N = 25) SD
x
98.5 95.2 98.2 102.4 101.7
12.8 11.8 13.9 10.9 12.9
*Significant difference from control group (analysis of variance, Neuman-Keuls, p < .05).
delays most often in the areas of verbal and abstract visual reasoning. Analyses of caregiving environments for the three groups indicated that all of the controls were living in nondrug-using households with their biologic mothers. Within the cocaine/polydrug group, 28 (30%) had lived since birth with their biologic mother who continued to use drugs, 26 (28%) had lived since birth with biologic mothers, who had achieved a drug- and alcohol-free status within 1 year after their children's births, and 23 (25%) had lived since shortly after birth with foster relatives in a drug- and alcohol-free environment. The remaining 16 children from Group 1 had been in foster nonrelative and/or multiple placements since birth. Among the polydrug/noncocaine exposed children, 12 (50%) had lived since birth with biologic mothers who continued to use drugs, 7 (29%) had lived since birth with drug- and alcohol-free biologic mothers, and 5 (21%) had lived with foster relatives in drug- and alcohol-free homes. Exposure to tobacco cigarettes postnatally continued in patterns similar to the prenatal exposure to tobacco. Analysis of the effects of caregiving environment on SBIS outcomes for cocaine/polydrug children are summarized in Table 4. Those Group 1 children who were continuing to live in a drug-using household were
J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:1, JANUARY 1994
TABLE 4 Developmental Outcome by Caregiving Environment for Cocaine/Polydrug Group Living with Drug-Using Biological Mother
N = 28 Living with drug-free biological mother N = 26 living with drug-free relative N = 23 % score S 84 on overall Stanford-Binet 25 4 13 % scoring S 84 on Sranford-Binet Verbal Reasoning 43 19 13 % scoring S 84 on Stanford-Binet Abstract/Visual Reasoning 32 12 9
*x2 (p ::;; .025). delayed by a standard deviation or more significantly more often on the verbal reasoning portion of the SBIS than were those living in drug-free environments. There were no significant differences acrosscaregiving environments on the SBIS for Group 2. Table 5 presents a summary of the blinded examiner ratings of test-taking behavior on the SBIS. The two drug-exposed groups were significantly more likely to show a preference for easy tasks (p < .05). No other group differences were noted for ratings of test-taking behaviors including the summative attention score. Results for the CBCL are presented in Table 6. Children were considered to be displaying problematic behavior if their T score on a given scale was greater than or equal to 60. Both drug exposed groups, as 23
GRIFFITH ET AL.
TABLE 5 Examiner Ratings of 3-Year Behavior on me Srandford-Binet Intelligence Scale Cocaine/Polydrug N Scoring
Distractibility Activity level Gives up easily Seeks to terminate Prefers easy tasks" Poor articulation Poor sound discrimination
46 25 48 38 37 36 20
~
4
Polydrug/Noncocaine %
54 29 56 44 44 42 23
N Scoring
~
4
14 12 14 16 11
12 9
%
60 54 60 69 48 54 39
Controls N Scoring 11
9 11 10 5 15 5
~
4
%
44 36 44 40 20 60 20
*X2 (p < .05)
compared with the control group, were rated by caregivers as displaying more destructive behavior (p < .05). The cocaine/polydrug group showed significantly greater numbers of children demonstrating aggressive behavior when compared with the control group. In addition, both drug groups had significantly greater numbers of children expressing externalizing behavior when compared with the control group. Gender differences were tested for each of the ourcome measures via factorial analyses. No gender differences were found for any of the SBIS intellectual outcome measures. On the SBIS behavioral ratings boys were found to be more active (p ~ .05) and to give up more easily (p ~ .05) when compared with girls. On the CBCL, male children tended to be rated as more destructive than females (p ~ .05). No other gender differences were found on the CBCL. Regression Results
The results from the stepwise regression analyses of intellectual and behavioral outcomes are presented in Table 7. The SBIS summative attention rating and (Cocaine exposure were found to be significant pre"dictors of lower SBIS Verbal Reasoning scores. The ' SBIS summative attention ratings, marijuana exposure, and the interaction of cocaine, marijuana , and alcohol exposure were found to be significant predictors of lower SBIS Abstract/Visual Reasoning scores. For the CBCL behavioral domains, the SBIS summarive attention rating and alcohol were found to be significant predictors of aggressive behaviors. Only the summative attention scale was noted to predict destructive behavior. Summative attention ratings and cocaine exposure were predictive of externalization.
24
None of the entered variables were significant predictors of the SBIS summative attention rating. DISCUSSION
In some respects the findings of the present study parallel those of the authors ' study of drug-exposed children through age 2 years (Chasnoff et al., 1992). That research indicated drug-exposed children , whether cocaine/polydrug exposed or polydrug/noncocaine exposed, continued through 2 years to display smaller head sizes as a group than did nonexposed children . The 2-year study additionally demonstrated that there were no differences between the two drug-exposed groups and the control group by age 2 years on a global measure of cognitive development such as the Bayley Mental Index. A final major finding of the 2-year study was the significant relationship between small head size and cocaine exposure. Findings of the present study, however, indicated that neither cocaine nor any other drug was predictive of small head size at 3 years of age. Each drug group , however, displayed smaller mean head sizes than did the control group. Although the .differences were not statistically significant, each drug group as compared with the control group had greater numbers of children falling below the tenth and the fifth percentiles for head circumference. The tendency for drug-exposed children to be born with smaller heads may be a major marker for predicting poor longterm developmental outcome (Eckerman et al. 1985, Emhart et al., 1987, Gross et al., 1983, and Lifschitz et al., 1985). The lack of catch-up growth in head size for those drug-exposed children with subnormal head sizes in the present study provides a stronger
J. AM . ACAD . CHILD ADOLESC . PSYCHIATRY, 33,1, JANUARY 1994
3-YEAR OUTCOME OF DRUG-EXPOSED CHILDREN
Problematic Behavior (T Score
~
TABLE 6 60) by Group on the Child Behavior Checklist
Cocaine/Polydrug (N = 55) N(T)
Social withdrawal Depressed Sleep problems Somatic problems Aggressive* Destructive* Internalizing Externalizing*
~
Polydrug/Noncocaine (N = 20)
%
60
23 18 20 22 18 27 18 20
13 10 11 12
10 15 10 11
N(T)
2 3 5 4 4 3 2 4
~
60
% 10 15 25 20 20 15 10 20
Controls (N = 17) N(T)
1 I
1 2 0 0 1 0
~
60
%
5 5 5 12
o o 6
o
*X2 (p :5 .05). TABLE 7 Regression Analyses Variable
B
<
P
Variance
Variable reasoning SBIS' Summative Attention Scale Cocaine
-.43 -.29
.000 .010
.19 .09
Total equation: R 2 = .28 Abstract Reasoning SBIS Summative Attention Scale Marijuana Cocaine/Marijuana!Alcohol
-.43 -.68 .40
.000 .000 .020
.26 .13 .05
SBIS Summative Attention Scale Alcohol
.30 .22
.001 .050
.09 .05
Total equation: R 2 = .14 CBCL destructive SBIS Summative Attention Scale
.25
.040
.04
Total equation: R 2 = .06 CBCL external SBIS Summative Attention Scale Cocaine
.25 .23
.030 .040
.08 .05
Total equation: R 2 = .44
CBCU Aggressive
Total equation: R 2 = .13 'SBIS = Stanford-Binet Intelligence Scale. bCBCL = Child Behavior Checklist.
indicator of potential problems. Hack et al. (1991), for example, found subnormal head size at 8 months of age to be predictive of poorer verbal and performance IQ scores at 8 years of age. The fact that subnormal head size at age 3 years did not predict intellectual performance at age 3 may
J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:1, JANUARY 1994
be due in part to the types of cognitive abilities one can assess in 3 year olds. It may be that the underlying problems represented by subnormal head size will be manifested in older children as they attempt more complex forms of learning and reasoning. Previous research into the developmental course of brain insult indicates that deficits often are delayed until later periods of development (Almli and Finger, 1984; Boll and Barth, 1981; and Tramontana and Hooper, 1988). Similar to the authors' 2-year study, there were no significant differences among the two drug groups and the control group on global measures of intellectual development. Although there were no group differences on the overall scores for the SBIS, the cocaine/polydrug group received significantly lower scores on verbal reasoning tasks and the polydrug/noncocaine group scored significantly lower on abstract/visual reasoning. The appearance of differences in intellectual performance at age 3 years between each of the drug groups and the control group may be in part because of the direct biologic effects of various drugs either singly or in combination. Results of the regression analysesfrom the present study support this hypothesis. Cocaine, for example, was shown to have a significant negative impact on verbal reasoning scores independent of the child's head circumference, other drugs of exposure, or the child's behavior as rated by examiner or caregiver.Marijuana and the combination of marijuana, cocaine, and alcohol were predictive of poor performance on abstract/visual reasoning when various confounding variables were partialed out. The group differences on specific areas of the SBIS at age 3 years represent the first research evidence
25
GRIFFITH ET AL.
linking prenatal cocaine exposure to long-term developmental outcome. Alcohol (Streissguth et al., 1989) and marijuana (Fried and Watkinson, 1990) have been linked to poor intellectual outcome in 4 year olds, but no interactive effects among marijuana, alcohol, and cocaine have been reported. As has been suggested by Chasnoff et al. (I 992) and Fried and Watkinson (1990) the emergence of drug-related deficits in older drug-exposed children . may represent the subtle effects that prenatal substance exposure has on the complex intellectual skills that develop throughout childhood. The significant findings in the present study relating drug exposure to lower scores on intellectual measures must be interpreted with extreme caution. It is important to note that in the present sample cocaine accounted for only 9% of the variance in verbal reasoning, marijuana accounted for 13% of the variance in abstract/visual reasoning, and the combination of cocaine, marijuana, and alcohol accounted for 5% of the variance in abstract/visual reasoning. Therefore to evaluate successfully the intellectual outcome of drug-exposed children, one must consider the multitude of other factors that contribute to the variance in intellectual outcome . The obvious factors that must be explored in greater detail are those differentiating the drug-using environment from the drugfree environment. In the present study, for example, children were much more likely to display problems in verbal reasoning if they were being raised in a home where drugs continued to be used. It is important to note that the drug-free homes in the present study represented permanent, stable placements for the children. Differences in outcome measures may not be as pronounced when comparing children raised in a stable yet drug-using environment with children raised in multiple drug-free placements. In addition to the effects of multiple placements, one has to consider the adaptive level of functioning within each placement. Previous research by Jeremy and Bernstein (1984) demonstrated that the best predictors of developmental outcome for methadone-exposed children and nonexposed children were the psychological resources of the mother. Future studies from the present authors will examine the ongoing intellectual development of drug-exposed children as affected by differences in personality, intelligence, social support systems, and parenting skills
26
between women who continue to use drugs versus those who have been able to quit. Research has yet to determine the roles of maternal and environmental factors as predictors of behavioral differences between drug-exposed children and nonexposed children. For the present, study exposure to drugs was linked to problem behaviors in 3 year olds. Examiner ratings indicated greater difficulty in sustaining attention during difficult tasks for the two drug groups as compared with the control group . Caregiver reports rated both drug- exposed groups as more aggressive than the controls. Caregivers rated the cocaine/polydrug-exposed children as more destructive than the drug-free controls. Whether these behaviors will continue as the child grows older is unknown. Analyses of predictive factors of problem behaviors indicated that prenatal alcohol exposure was predictive of aggression (accounting for 5% of the variance). Intrauterine cocaine exposure was predictive of externality, which represents behaviors characterized as aggressive and/or destructive. Cocaine, however, accounted for only 5% of the variance in externality. Perhaps the most significant finding from the present study was that among all variables considered the blinded examiners' ratings via the summative attention scale provided the strongest predictor of poor verbal reasoning, poor nonverbal reasoning, aggression, destructiveness, and externality. These findings highlight the importance of using the observations and judgment of trained clinicians as sources of information concerning the overall functioning of the child. Examiner clinical judgment will be particularly important in documenting any subtle effects that prenatal substance exposure may have on children's behavioral and intellectual functioning. The findings of the present study represent a bestcase scenario of the developmental and behavioral outcome of children exposed prenatally to drugs. The majority of the drug-exposed children in the present study scored within the average ranges for intellectual abilities and displayed no significant behavioral problems. These children, however, represent a select sample of drug-exposed children for whom major prenatal risk factors were reduced and early, and continuous medical and developmental assessment, diagnosis, and intervention were provided. Contrary to information in the popular media, not all substance-exposed children suffer the same poor
J . AM. ACAD . CHILD ADOLES C. PSYCHIATRY, 33:1, JANUARY 1994
3-YEAR OUTCOME OF DRUG-EXPOSED CHILDREN
prognosis. In fact, generalizations about the fate of drug-exposed children must await additional research into the outcome of the broader population of drugexposed children. Future research must examine the roles of maternal and environmental factors across a variety ofgeographic locations and socioeconomic levels in predicting differences between drug-exposed children and nonexposed children. No research is available on the long-term social, emotional, behavioral, and intellectual outcomes of children exposed to drugs in multirisk environments in the absence of intervention services. Lack of prenatal care, poor prenatal nutrition, abuse, neglect, multiple placements, poor postnatal nutrition, and poor medical care must all be considered in evaluating the outcome of drug-exposed children .
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J . AM . ACAD. CHILD ADOLESC . PSYCHIATRY, 33:1, JANUARY 1994
Boll T] , Barth]T (1981), Neuropsychology of brain damage in children. In: Handbook of Clinical Neuropsychology, eds, SB Filskov, T] Boll. New York: Wiley, pp 418-452 Chasnoff I], Griffith DR, Freier C, Murray] (1992), Cocaine/polydrug use in pregnancy: twO year follow-up. Pediatr 89:284-289 Eckerman CO , Lynne AS, Gross S] (1985), Different developmental courses for very-low birthweight infants. Developmental Psychology 21:813-8 27 Emhart CB, Marler MR, Morrow-Tlucak M (1987), Head size and cognitive development in the early preschool years. Psycho' Reports 61:103-106 Fried PA, Watkinson B (1990), 36- and 48-month neurobehavioral followup of children prenatally exposed to marijuana, cigarettes, and alcohol.
J Dev Behav Pediatr 11 :49-58 Gomby OS, Shiono PH (1991), Estimating the number of substanceexposed infants. Future Child 1:17-25 Gross S], Oehler ]M, Eckreman CO (1983), Head growth and development outcome in very low birthweight infants. Pediatrics 71:70-75 Hack M, Breslan N , Weissman B, Aram 0 , Klein N, Borawski E (1991), Effects of very low birthweight and subnormal head size on cognitive abilities at school age. N EnglJ Med 325:231-237 Jeremy R, Bernstein VJ (1984), Dyads at risk: methadone-maintained women and their four month old infants. Child Dev 55:1141-1154 Lifschirz MH , Wilson GS, Smith EO , Desmond MM (1985), Factors affecting head growth and intellectual function in children of drug addicts. Pediatrics 75: 269-274 Streissguth AP, Barr HM , Sampson PO , Darby BL, Mart in DC (1989), IQ at age 4 in relation to maternal alcohol use and smoking during pregnancy. Developmental Psychology 25:3-11 Thorndike RL, Hagen EP, Sattler]M (1984), TheStanford-Bina Intelligence Scale: Fourth Edition, Chicago: Riverside Publishing Tramontana MG, Hooper SR (1988), Assessment Issues in ChildNeuropsycbology. New York: Plenum Press
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