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Correlations between age and higher cognitive function in schizophrenia subgroups
Schizophrenia Research 61 (2003) 325 – 326 www.elsevier.com/locate/schres
Letter to the Editors Correlations between age and higher cognitive $ function in schizophrenia subgroups Studies of age effects on cognitive function in schizophrenia have produced mixed findings. We previously studied this association by obtaining correlations between age and an index of cognitive function in two subgroups of schizophrenia patients that had extreme differences in level of cognitive function (Goldstein et al., 1998). One of them reflected near normal cognitive ability while the other had severely impaired cognitive function. We computed correlation coefficients between age and scores on the Average Impairment Rating (AIR), an index of cognitive impairment based upon the Halstead– Reitan Neuropsychological Test Battery. Patients with near normal cognitive function generated approximately the same correlations between age and the AIR as a patient control sample, consistent with normal aging. Patients with severe cognitive impairment produced zero-order correlations with age. We present here an elaboration of these findings providing age correlations for individual tests of higher cognitive abilities and additional subgroups of patients with schizophrenia. The additional subgroups were derived from cluster analyses reported on in previous studies (Seaton et al., 2001). Four clusters were identified; two extreme ones and two intermediate clusters demonstrating moderate cognitive impairment with differing cognitive profiles that varied in intactness of psychomotor function. Participants in this study included 223 male patients with schizophrenia. Methods for diagnosis, evaluation of medication status, and characterization of the sample have been described elsewhere (Goldstein, 1990; Goldstein and Shemansky, 1995). The
$ This research was supported by the Medical Research Service, Department of Veterans Affairs.
neuropsychological assessment included the Halstead Category Test total errors, Trailmaking Test B time, Tactual Performance Test (TPT) total time (Reitan and Wolfson, 1993) and the Wisconsin Card Sorting Test—categories achieved (Heaton et al., 1993). Pearson r correlations between age and individual test scores are presented in Table 1. There were three significant correlations with age and in the Near Normal group plus one borderline ( p < 0.10) result, one in the Moderate Psychomotor groups, and none in the Severe and Moderate groups. There were four significant correlations in the patient control group. The AIR produced significant correlations only in the Near Normal schizophrenia cluster, and the patient control group. These correlational data indicate that patients with schizophrenia do not have the same association between cognitive function and age, as do individuals without schizophrenia. Patient controls demonstrated the anticipated moderate statistically significant correlations between age and cognitive performance. There were numerous zero-order correlations across cognitive tests with age in the three impaired schizophrenia clusters. With the exception of the Near Normal group, age correlations are similar to what is found in individuals with severe brain injury that diminishes the normal association between age and cognitive function. The possibility therefore exists that once moderate or severe cognitive dysfunction
Table 1 Correlations between age and neurocognitive tests used in schizophrenia clusters and patient controls Severe Moderate motor Category test TPT Trail making B WCST-categories AIR
0920-9964/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S0920-9964(02)00313-4
0.20 0.03 0.22 0.08 0.05
0.27 0.44*** 0.08 0.09 0.14
Moderate Near Patient normal control 0.21 0.12 0.10 0.11 0.00
0.23* 0.19 + 0.29** 0.06 0.38**
0.35*** 0.30*** 0.29*** 0.25 + 0.44***
326
Letter to the Editors
in schizophrenia appears, the normal association between aging and cognitive changes essentially disappears. A possible exception is the high correlation between the TPT and age in the Moderate Motor subgroup, suggesting the possibility of deterioration of psychomotor function in this subgroup. It therefore appears that the four schizophrenia clusters previously described have course of illness implications that merit further study.
chological Test Battery: Theory and Clinical Interpretation, 2nd ed. Neuropsychology Press, Tucson. Seaton, B.E., Goldstein, G., Allen, D.N., 2001. Sources of heterogeneity in schizophrenia: the role of neuropsychological functioning. Neuropsychol. Rev. 11, 45 – 67.
William P. Horan University of California, Los Angeles, CA, USA E-mail address: [email protected] and
References Goldstein, G., 1990. Neuropsychological heterogeneity in schizophrenia: a consideration of abstraction and problem-solving abilities. Arch. Clin. Neuropsychol. 5, 251 – 264. Goldstein, G., Shemansky, W.J., 1995. Influences on cognitive heterogeneity in schizophrenia. Schizophr. Res. 18, 59 – 69. Goldstein, G., Allen, D.N., van Kammen, D.P., 1998. Individual differences in cognitive decline in schizophrenia. Am. J. Psychiatry 155, 1117 – 1118. Heaton, R.K., Chelune, G.J., Talley, J.L., Kay, G.G., Curtiss, G., 1993. Wisconsin Card Sorting Test Manual. Psychological Assessment Resources, Odessa, FL. Reitan, R.M., Wolfson, D., 1993. The Halstead – Reitan Neuropsy-
Gerald Goldstein * VA Pittsburgh Healthcare System, 7180 Highland Drive, University of Pittsburgh, Pittsburgh, PA 5206, USA 26 December 2001
* Corresponding author. Tel.: +1-412-365-5232; fax: +1-412365-5231.
Letter to the Editors Correlations between age and higher cognitive $ function in schizophrenia subgroups Studies of age effects on cognitive function in schizophrenia have produced mixed findings. We previously studied this association by obtaining correlations between age and an index of cognitive function in two subgroups of schizophrenia patients that had extreme differences in level of cognitive function (Goldstein et al., 1998). One of them reflected near normal cognitive ability while the other had severely impaired cognitive function. We computed correlation coefficients between age and scores on the Average Impairment Rating (AIR), an index of cognitive impairment based upon the Halstead– Reitan Neuropsychological Test Battery. Patients with near normal cognitive function generated approximately the same correlations between age and the AIR as a patient control sample, consistent with normal aging. Patients with severe cognitive impairment produced zero-order correlations with age. We present here an elaboration of these findings providing age correlations for individual tests of higher cognitive abilities and additional subgroups of patients with schizophrenia. The additional subgroups were derived from cluster analyses reported on in previous studies (Seaton et al., 2001). Four clusters were identified; two extreme ones and two intermediate clusters demonstrating moderate cognitive impairment with differing cognitive profiles that varied in intactness of psychomotor function. Participants in this study included 223 male patients with schizophrenia. Methods for diagnosis, evaluation of medication status, and characterization of the sample have been described elsewhere (Goldstein, 1990; Goldstein and Shemansky, 1995). The
$ This research was supported by the Medical Research Service, Department of Veterans Affairs.
neuropsychological assessment included the Halstead Category Test total errors, Trailmaking Test B time, Tactual Performance Test (TPT) total time (Reitan and Wolfson, 1993) and the Wisconsin Card Sorting Test—categories achieved (Heaton et al., 1993). Pearson r correlations between age and individual test scores are presented in Table 1. There were three significant correlations with age and in the Near Normal group plus one borderline ( p < 0.10) result, one in the Moderate Psychomotor groups, and none in the Severe and Moderate groups. There were four significant correlations in the patient control group. The AIR produced significant correlations only in the Near Normal schizophrenia cluster, and the patient control group. These correlational data indicate that patients with schizophrenia do not have the same association between cognitive function and age, as do individuals without schizophrenia. Patient controls demonstrated the anticipated moderate statistically significant correlations between age and cognitive performance. There were numerous zero-order correlations across cognitive tests with age in the three impaired schizophrenia clusters. With the exception of the Near Normal group, age correlations are similar to what is found in individuals with severe brain injury that diminishes the normal association between age and cognitive function. The possibility therefore exists that once moderate or severe cognitive dysfunction
Table 1 Correlations between age and neurocognitive tests used in schizophrenia clusters and patient controls Severe Moderate motor Category test TPT Trail making B WCST-categories AIR
0920-9964/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S0920-9964(02)00313-4
0.20 0.03 0.22 0.08 0.05
0.27 0.44*** 0.08 0.09 0.14
Moderate Near Patient normal control 0.21 0.12 0.10 0.11 0.00
0.23* 0.19 + 0.29** 0.06 0.38**
0.35*** 0.30*** 0.29*** 0.25 + 0.44***
326
Letter to the Editors
in schizophrenia appears, the normal association between aging and cognitive changes essentially disappears. A possible exception is the high correlation between the TPT and age in the Moderate Motor subgroup, suggesting the possibility of deterioration of psychomotor function in this subgroup. It therefore appears that the four schizophrenia clusters previously described have course of illness implications that merit further study.
chological Test Battery: Theory and Clinical Interpretation, 2nd ed. Neuropsychology Press, Tucson. Seaton, B.E., Goldstein, G., Allen, D.N., 2001. Sources of heterogeneity in schizophrenia: the role of neuropsychological functioning. Neuropsychol. Rev. 11, 45 – 67.
William P. Horan University of California, Los Angeles, CA, USA E-mail address: [email protected] and
References Goldstein, G., 1990. Neuropsychological heterogeneity in schizophrenia: a consideration of abstraction and problem-solving abilities. Arch. Clin. Neuropsychol. 5, 251 – 264. Goldstein, G., Shemansky, W.J., 1995. Influences on cognitive heterogeneity in schizophrenia. Schizophr. Res. 18, 59 – 69. Goldstein, G., Allen, D.N., van Kammen, D.P., 1998. Individual differences in cognitive decline in schizophrenia. Am. J. Psychiatry 155, 1117 – 1118. Heaton, R.K., Chelune, G.J., Talley, J.L., Kay, G.G., Curtiss, G., 1993. Wisconsin Card Sorting Test Manual. Psychological Assessment Resources, Odessa, FL. Reitan, R.M., Wolfson, D., 1993. The Halstead – Reitan Neuropsy-
Gerald Goldstein * VA Pittsburgh Healthcare System, 7180 Highland Drive, University of Pittsburgh, Pittsburgh, PA 5206, USA 26 December 2001
* Corresponding author. Tel.: +1-412-365-5232; fax: +1-412365-5231.