Genetic association of DRD2 polymorphisms with anxiety scores among alcohol-dependent patients

Available online at www.sciencedirect.com

Biochemical and Biophysical Research Communications 371 (2008) 591–595 www.elsevier.com/locate/ybbrc

Genetic association of DRD2 polymorphisms with anxiety scores among alcohol-dependent patients Keun-Ho Joe a, Dai-Jin Kim b,*, Byung Lae Park c, Sujung Yoon d, Hae-Kook Lee e, Tae-Suk Kim b, Young-Hoon Cheon f, Do-Hoon Gwon g, Sung-Nam Cho g, Hye Won Lee c, Suk NamGung c, Hyoung Doo Shin c,h,* a

Department of Social Welfare with Addiction Rehabilitation, Eulji University, 143-5, Yangji-Dong, Sungnam, Kyounggi-do 461-713, Republic of Korea b Department of Psychiatry, Holy Family Hospital, College of Medicine, Catholic University of Korea, 2 Sosa-dong, Buchon-City, Kunggi, Wonmi-Gu, Pucheon, Kyounggi-do 420-717, Republic of Korea c Department of Genetic Epidemiology, SNP Genetics, Inc., Room 1407, 14th Floor, Complex B, WooLim Lion’s Valley, 371-28, Gasan-Dong, Geumcheon-Gu, Seoul 153-801, Republic of Korea d Department of Psychiatry, St. Paul’s Hospital, College of Medicine, Catholic University of Korea, 620-56, Jeonnong 2 dong, Dongdaemun-gu, Seoul 130-709, Republic of Korea e Department of Psychiatry, Uijeongbu St. Mary’s Hospital, College of Medicine, Catholic University of Korea, 65-1, Geumo-dong, Uijeongbu, Kyounggi-do 480-130, Republic of Korea f Department of Psychiatry, Incheon Chamsarang Hospital 511-6, Gajeong-dong, Seo-gu, Incheon 404-230, Republic of Korea g Department of Psychiatry, Bugok National Hospital, 70 Bugok-ri, Bogok-Myeon, Changnyeong-gun, Gyeongsangnam-do 635-893, Republic of Korea h Department of Life Science, Sogang University, Shinsu-ding, Seoul 121-742, Rupublic of Korea Received 22 January 2008 Available online 26 February 2008

Abstract The dopaminergic neurotransmission system is one of the major factors in development of alcoholism and also contributes to anxiety and depression. In this study, the associations of the dopamine receptor type 2 (DRD2) polymorphisms with the symptoms of anxiety were analyzed. A total of 573 alcoholics and 273 controls were enrolled in the study from the Korean population. Five DRD2 SNPs, including 32869 A>G, 32768 insdel C, +11890 C>G, +11915 C>T, and +32806 C>T, were genotyped using a TaqMan assay and analyzed with various alcoholic phenotypes. Although no DRD2 polymorphisms were associated with the risk of alcoholism, +32806 C>T and Block2-ht1 showed associations (in dominant models) with both the state anxiety level scale (STAI-S) and the trait anxiety level scale (STAI-T) (P = 0.004 and P = 0.003, and P = 0.01 and P = 0.005, respectively). In addition, the 32768 insdel C also showed positive association with both anxiety level scales in recessive models (P = 0.01 and P = 0.02, respectively). Ó 2008 Elsevier Inc. All rights reserved. Keywords: DRD2; Polymorphism; Alcoholism; STAI-S; STAI-T

Excessive alcohol drinking is often accompanied by anxiety and depression. The Epidemiological Catchment Area (ECA) survey, performed in the 1980s, reported that estimated prevalence of any form of anxiety disorder was

* Corresponding authors. Fax: +82 32 340 2670 (D.J. Kim), +82 2 2026 4299 (H.D. Shin). E-mail addresses: [email protected] (D.-J. Kim), [email protected] (H.D. Shin).

0006-291X/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2008.02.076

19.4% in patients with an alcohol-related disorder [1]. A meta-analysis to determine an estimated lifetime prevalence rate reported that 44% of alcohol-related disorder patients showed symptoms of anxiety disturbance, about three times higher than the rate in community samples [2]. The National Co-morbidity Survey (NCS), performed from 1990 to 1992, reported that, in male alcoholics, the odds ratio of having a panic disorder was 2.3 and the odds ratio of having a generalized anxiety disorder was 3.9 [3]. The lifetime odds ratio for generalized anxiety disorder was

592

K.-H. Joe et al. / Biochemical and Biophysical Research Communications 371 (2008) 591–595

calculated as 2.2 in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) [4]. Genetic predisposition is one of the main factors in the development of alcoholism. According to the results of the Collaborative Study on the Genetics of Alcoholism (COGA), alcoholism and depression tend to occur together, and chromosome 1 was suggested to be a candidate gene for the genetic linkage between the two disorders [5]. The polymorphisms of the dopamine D2 receptor (DRD2) gene are thought to be related to symptoms of anxiety and depression in alcohol-dependent patients [6– 8]. By bromocriptine administration, the alcoholics with the TaqIA A1 allele (‘‘C” allele of +32806 C>T in this study) showed improvement in craving and anxiety [9]. The TaqIA A1 allele of DRD2 was also reported to have an association with low neuroticism-anxiety personality traits [10]. In a Chinese study, the DRD2 polymorphism showed no direct relationship with alcohol dependence itself, but a subpopulation with co-morbid depression and anxiety symptoms among the alcoholics presented a higher rate of TaqIA A1 allele frequency [11]. In the present study, we investigated the relationships between the DRD2 polymorphisms and symptoms of anxiety among alcohol-dependent patients. Methods and materials Subjects. Alcohol-dependent patients in three hospitals in Korea (Holy Family Hospital, Chamsarang Mental Hospital, Chunchon Mental Hospital) were recruited. All (n = 573) were diagnosed using the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) criteria [12]. All of the patients enrolled in this study had in-patient status for more than 30 days due to their drinking problem and did not have any current physical or neurological illness. The population controls (n = 273, all male) consisted of randomly selected, 20-year-old healthy individuals who visited the Catholic University of Korea Holy Family Hospital for a regular health check-up. After a detailed explanation about the process of this study, informed consent was obtained. The Institutional Review Board of each hospital had approved the study. After alcohol abstinence of 30 days or more, data from the following tests (Korean versions) were obtained from the alcohol-dependent subjects (n = 573): a questionnaire about their drinking behavior, the Alcohol Use Disorders Identification Test (AUDIT-K) [13], the Alcohol Dependence Scale (ADS-K) [14], the Beck Depression Inventory (BDI-K) [15], and the State-Trait Anxiety Inventory (K-STAI) [16]. The clinical parameters are summarized in Table 1.

Table 1 Clinical profiles of study subjects Description

Alcoholics

Population controls

N Age STAI-State (state anxiety level scale) STAI-Trait (trait anxiety level scale) BDI scale (depression scale) AUDIT score (test for alcohol dependence) ADS (alcohol dependence scale) Duration of alcohol dependence (months)

535 46.89(20–73) 48.68 ± 11.09 48.02 ± 9.85 20.39 ± 11.49 23.86 ± 8.46

273 20.00(20–20) — — — —

19.28 ± 10.54 237.20 ± 168.14

— —

Genotyping of DRD2 polymorphisms. Five SNP loci in the DRD2 gene, including 32869 A>G, 32768 insdel C, +11890 C>G, +11915 C>T, and +32806 C>T (TaqIA in previous studies), were analyzed. For genotyping of these polymorphic sites, the amplifying primers and probes were designed for TaqMan [17]. Primer Express (Applied Biosystems) was used to design both the PCR primers and the MGB TaqMan probes (Supplementary Table 1). The PCR was carried out as described previously [6]. Statistics. v2 tests were used to determine if the individual variant was in Hardy–Weinberg equilibrium. Haplotypes (ht) of each individual were inferred using PHASE software [18]. Phase probabilities of each site were calculated for each individual with this software. Individuals with phase probabilities of less than 97% were excluded from the analysis. The genetic effects of the inferred haplotypes were analyzed in the same way as the polymorphisms. Haplotypes with either equivalence with single polymorphisms or with frequencies less than 5% were excluded in statistical analysis. Logistic regression analyses were used to calculate the P-value for case-control analysis, and multiple regressions were used for association analyses of alcoholic phenotypes while adjusting for age, family history, and alcoholic duration as covariates.

Results The five polymorphisms in DRD2 were analyzed in this study. The allele frequency, heterozygosity, and Hardy– Weinberg equilibrium co-efficiency were assessed and are presented on Supplementary Table 1. All polymorphisms were not significantly different between alcoholics and population controls in our result. Linkage disequilibrium coefficients (|D0 | and r2) among polymorphisms were also calculated, and DRD2 can be parsed into two haplotype blocks (1 and 2). There were three and five common haplotypes in block1 and block2, respectively (Supplementary Table 2). DRD2 32869 A>G and DRD2 32768 insdel C are equivalent with block1-ht3 and block1-ht2, respectively, and DRD2 +11890 C>G and DRD2 +32806 C>T are almost equivalent with block2-ht3 and block2-ht2, respectively. DRD2 block1-ht2, DRD2 block1-ht3, DRD2 block2-ht2, and DRD2 block2-ht3 were omitted from further analysis, and DRD2 block2-ht4 and DRD2 block2ht5 were also omitted due to their low frequency (Supplementary Table 2). The means of STAI-S and STAI-T scores in the alcohol-dependent patients were 48.68 ± 11.09 and 48.02 ± 9.85, respectively (Table 1). The data from both were above the means in the ordinary Korean population (41.09 and 42.38, respectively) [16]. Logistic regression analysis of each polymorphism and common haplotypes (block1-ht1 and block2-ht1) with the risk of alcoholism showed no positive associations (Table 2). However, DRD2 polymorphisms were significantly associated with the symptoms of anxiety among alcohol-dependent patients (Table 3). Patients with the ‘‘CC” genotype of DRD2 +32806 C>T showed higher STAI-S and STAI-T scores than those with other genotypes (P = 0.004 and 0.005, respectively). Similar findings were observed in haplotype analysis. The STAI-S and STAI-T scores of block2-ht1/ht1-bearing patients were also higher than those of others (P = 0.003 and 0.005, respectively). On

K.-H. Joe et al. / Biochemical and Biophysical Research Communications 371 (2008) 591–595

593

Table 2 Logistic analysis of DRD2 polymorphisms among alcoholic patients and population controls in Korean male subjects Loci

32869 A>G 32768 insdel C +11890 C>G +11915 C>T +32806 C>T

Position

Amino acid change

rs#

Genotype

Promoter

rs1799978

Promoter

—

Exon7

S311C

rs1801028

Exon7

P319P

rs6277

30

rs1800497

A 584 Ins 550 C 751 C 716 C 290

AG 193 Insdel 221 CG 50 CT 81 CT 358

Frequency

G 18 Del 25 G 0 T 5 T 135

N 795 N 796 N 801 N 802 N 783

Heterozygosity

HWE

Minor allele frequency

P

Alcoholic

PCa

Alcoholic (n = 529)

PCa (n = 273)

0.144

0.247

0.939

0.974

0.138

0.155

0.37

0.170

0.282

0.840

0.227

0.174

0.162

0.55

0.031

0.060

0.734

0.896

0.033

0.028

0.54

0.057

0.107

0.990

0.057

0.059

0.053

0.66

0.401

0.480

0.063

0.792

0.402

0.399

0.89

Logistic regression models were used to calculate P-values of codominant model. a Population controls.

Table 3 Regression association analysis of DRD2 polymorphisms for age-, family history-, and alcoholic duration-adjusted STAI-State and STAI-Trait scores among alcoholic dependent subjects Anxiety level scale Loci STAI-State

STAI-Trait

Rare allele Amino acid change C/C

32869 A>G G 32768 insdel C DelC +11890 C>G G +11915 C>T T +32806 C>T T Block1-ht1 — Block2-ht1 — 32869 A>G G 32768 insdel C DelC +11890 C>G G +11915 C>T T +32806 C>T T Block1-ht1 — Block2-ht1 —

S311C P319P

S311C P319P

R/R

Pa

Pb

Pc

249(48.87 ± 11.10) 70(48.27 ± 11.03) 225(48.53 ± 10.73) 91(50.40 ± 11.55) 311(48.76 ± 11.32) 18(47.44 ± 6.08) 293(48.44 ± 11.35) 35(50.43 ± 8.66) 121(50.83 ± 10.33) 142(47.49 ± 12.25) 158(49.05 ± 11.00) 137(48.56 ± 10.82) 87(51.45 ± 11.14) 163(47.37 ± 12.05)

C/R

6(48.00 ± 6.07) 10(40.40 ± 9.24) — 1(58.00) 58(47.36 ± 8.35) 28(48.14 ± 12.19) 79(48.34 ± 8.21)

0.78 0.63 0.73 0.23 0.02 0.55 0.06

0.78 0.64 0.73 0.25 0.004 0.59 0.003

0.91 0.01 — 0.54 0.38 0.69 0.9

250(48.41 ± 9.60) 69(47.26 ± 10.85) 225(48.07 ± 9.87) 91(49.03 ± 10.07) 311(48.22 ± 10.11) 18(46.44 ± 5.89) 293(47.94 ± 10.09) 35(49.43 ± 8.49) 120(49.67 ± 9.54) 141(47.63 ± 10.79) 159(48.71 ± 9.73) 136(47.52 ± 9.71) 86(50.40 ± 10.24) 162(47.31 ± 10.46)

6(47.50 ± 10.56) 10(42.50 ± 8.25) — 1(57.00) 60(46.23 ± 7.95) 28(47.86 ± 11.77) 81(47.33 ± 8.05)

0.56 0.48 0.54 0.26 0.02 0.33 0.04

0.53 0.97 0.54 0.28 0.01 0.26 0.005

0.93 0.02 — 0.56 0.17 0.82 0.58

Genotype and haplotype distributions, means ± SD of each value, and P-values for regression analyses are shown. C/C, C/R, and R/R represent homozygotes for the common allele, and heterozygotes and homozygotes for the rare allele, respectively. Pa, Pb, and Pc refer to P-values of codominant, dominant, and recessive models, respectively. Bold values indicate the case of P < 0.05 *

other hand, the del/del homozygote of DRD2 32768 insdel C showed relatively lower STAI-S and STAI-T scores than the others (P = 0.01 and 0.02 in the recessive model, respectively). Discussion The relationship between the polymorphisms in DRD2 and alcohol dependence is still controversial. Some researchers have suggested that DRD2 polymorphisms are not associated with alcoholism itself or the behavioral patterns of alcoholism in diverse populations [19–21]. In contrast, several studies have reported positive results, especially regarding 32768 insdel C and +32806 C>T (TaqIA) [22–24], and it has thus been demonstrated that DRD2 polymorphisms could be at least partially responsible for problems due to drinking and alcohol dependence.

In this study, no DRD2 polymorphisms were associated with the development of alcoholism in Korean subjects as has been reported in previous study [6]. However, several DRD2 polymorphisms showed associations with several phenotypes derived from alcoholism such as state-anxiety inventory-state (STAI-S) and stateanxiety inventory-trait (STAI-T) (Table 3). Scores on the STAI-S anxiety scale increase in response to physical danger and psychological stress, and decrease as a result of relaxation training. On the STAI-T anxiety scale, consistent with the trait anxiety construct, psychoneurotic and depressed patients generally have high scores. Scores on the STAI tests have a direct interpretation: high scores on their respective scales mean more of the trait or state anxiety and low scores mean less. In previous studies, the A1 allele (C allele) of +32806 C>T was reported to have linkages with early onset of alcohol dependence [25,26]. The A1 allele of

594

K.-H. Joe et al. / Biochemical and Biophysical Research Communications 371 (2008) 591–595

+32806 C>T was also reported to be associated with a high level of anxiety, depression, and social dysfunction in patients with post-traumatic stress disorder (PTSD) [27]. Moreover, harmful drinking in the patients with PTSD was associated with this A1 allele [28]. However, the involvement of the dopaminergic system on the development of depressive symptoms in alcoholics is still vague. One study, which looked at 23 mood-disordered families, concluded that DRD2 has no major relationship to mood disorder [29]. However, the A1/A1 genotype of +32806 C>T would be more frequent in alcoholic subjects with anxiety/depressive symptoms than in the pure alcoholics [11,30]. In summary, we have analyzed five known polymorphisms in the human DRD2 gene in our alcoholic cohort. Statistical analysis revealed that no DRD2 polymorphisms were contributors to the development of alcoholism in Korean subjects. However, 32768 insdel C and +30806 C>T (TaqIA) showed significant association with the anxiety symptoms in alcohol dependence among alcoholdependent patients. Acknowledgments This study was supported by a grant from the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (03-PJ10-PG13-GD01-0002), and a grant from the Biomedical Brain Research Center of the Korea Health 21 R&D Project funded by the Ministry of Health & Welfare, Republic of Korea. (A040042). Financial support was also provided by the Catholic Medical Center Research Foundation in the program year of 2006. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.bbrc. 2008.02.076. References [1] D.A. Regier, M.E. Farmer, D.S. Rae, B.Z. Locke, S.J. Keith, L.L. Judd, F.K. Goodwin, Comorbidity of mental disorders with alcohol and other drug abuse. Results from the epidemiologic catchment area (ECA) study, Jama 264 (1990) 2511–2518. [2] M.G. Kushner, K.J. Sher, B.D. Beitman, The relation between alcohol problems and the anxiety disorders, Am. J. Psychiatry 147 (1990) 685–695. [3] R.C. Kessler, R.M. Crum, L.A. Warner, C.B. Nelson, J. Schulenberg, J.C. Anthony, Lifetime co-occurrence of DSM-IIIR alcohol abuse and dependence with other psychiatric disorders in the national comorbidity survey, Arch. Gen. Psychiatry 54 (1997) 313–321. [4] B.F. Grant, D.S. Hasin, F.S. Stinson, D.A. Dawson, W. June Ruan, R.B. Goldstein, S.M. Smith, T.D. Saha, B. Huang, Prevalence, correlates, co-morbidity, and comparative disability of DSM-IV generalized anxiety disorder in the USA: results from the national epidemiologic survey on alcohol and related conditions, Psychol. Med. 35 (2005) 1747–1759.

[5] J.I. Nurnberger Jr., T. Foroud, L. Flury, E.T. Meyer, R. Wiegand, Is there a genetic relationship between alcoholism and depression? Alcohol Res. Health 26 (2002) 233–240. [6] D.J. Kim, B.L. Park, S. Yoon, H.K. Lee, K.H. Joe, Y.H. Cheon, D.H. Gwon, S.N. Cho, H.W. Lee, S. NamGung, H.D. Shin, 50 UTR polymorphism of dopamine receptor D1 (DRD1) associated with severity and temperament of alcoholism, Biochem. Biophys. Res. Commun. 357 (2007) 1135–1141. [7] U. Finckh, H. Rommelspacher, S. Kuhn, P. Dufeu, G. Otto, A. Heinz, M. Dettling, M. Giraldo-Velasquez, J. Pelz, K.J. Graf, H. Harms, T. Sander, L.G. Schmidt, A. Rolfs, Influence of the dopamine D2 receptor (DRD2) genotype on neuroadaptive effects of alcohol and the clinical outcome of alcoholism, Pharmacogenetics 7 (1997) 271–281. [8] J. Samochowiec, M. Ladehoff, J. Pelz, M. Smolka, L.G. Schmidt, H. Rommelspacher, U. Finckh, Predominant influence of the 30 -region of dopamine D2 receptor gene (DRD2) on the clinical phenotype in German alcoholics, Pharmacogenetics 10 (2000) 471–475. [9] B.R. Lawford, R.M. Young, J.A. Rowell, J. Qualichefski, B.H. Fletcher, K. Syndulko, T. Ritchie, E.P. Noble, Bromocriptine in the treatment of alcoholics with the D2 dopamine receptor A1 allele, Nat. Med. 1 (1995) 337–341. [10] J. Wacker, M. Reuter, J. Hennig, G. Stemmler, Sexually dimorphic link between dopamine D2 receptor gene and neuroticism-anxiety, Neuroreport 16 (2005) 611–614. [11] S.Y. Huang, W.W. Lin, H.C. Ko, J.F. Lee, T.J. Wang, Y.H. Chou, S.J. Yin, R.B. Lu, Possible interaction of alcohol dehydrogenase and aldehyde dehydrogenase genes with the dopamine D2 receptor gene in anxiety-depressive alcohol dependence, Alcohol Clin. Exp. Res. 28 (2004) 374–384. [12] A.P. Association, Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) criteria, American Psychiatric Association, 1994. [13] B.O. Lee, C.H. Lee, P.G. Lee, M.J. Choi, K. Namkoong, Development of Korean version of alcohol use disorders identification test (AUDIT-K): its reliability and validity, The Korean Academy of Add Psy 4 (2000) 83–92. [14] D.K. Lee, J.K. Shin, S.M. Yun, W.T. Byun, A reliability and validity study of the Korean version of the alcohol dependence scale in alcoholics, The Korean Academy of Add Psy 4 (2000) 30–37. [15] M.S. Shin, Z.S. Kim, K.B. Park, The cut-off score for the Korean version of Beck depression inventory, Korean J. Clin. Psychol. 12 (1993) 71–81. [16] D.W. Hahn, C.H. Lee, K.K. Chon, Korean adaptation of Spielberger’s STAI (K-STAI), Korean J. Health Psychol. 1 (1996) 1–14. [17] K.J. Livak, Allelic discrimination using fluorogenic probes and the 50 nuclease assay, Genet. Anal. 14 (1999) 143–149. [18] M. Stephens, N.J. Smith, P. Donnelly, A new statistical method for haplotype reconstruction from population data, Am. J. Hum. Genet. 68 (2001) 978–989. [19] J. Gelernter, H. Kranzler, D2 dopamine receptor gene (DRD2) allele and haplotype frequencies in alcohol dependent and control subjects: no association with phenotype or severity of phenotype, Neuropsychopharmacology 20 (1999) 640–649. [20] B.C. Haberstick, D. Timberlake, A. Smolen, J.T. Sakai, C.J. Hopfer, R.P. Corley, S.E. Young, M.C. Stallings, D. Huizinga, S. Menard, C. Hartman, J. Grotpeter, J.K. Hewitt, Between and within-family association test of the dopamine receptor D2 TaqIA polymorphism and alcohol abuse and dependence in a general population sample of adults, J. Stud. Alcohol Drugs 68 (2007) 362–370. [21] T. Sander, M. Ladehoff, J. Samochowiec, U. Finckh, H. Rommelspacher, L.G. Schmidt, Lack of an allelic association between polymorphisms of the dopamine D2 receptor gene and alcohol dependence in the German population, Alcohol Clin. Exp. Res. 23 (1999) 578–581. [22] U. Berggren, C. Fahlke, E. Aronsson, A. Karanti, M. Eriksson, K. Blennow, D. Thelle, H. Zetterberg, J. Balldin, The taqI DRD2 A1

K.-H. Joe et al. / Biochemical and Biophysical Research Communications 371 (2008) 591–595

[23]

[24]

[25]

[26]

[27]

allele is associated with alcohol-dependence although its effect size is small, Alcohol Alcohol 41 (2006) 479–485. E.P. Noble, X. Zhang, T.L. Ritchie, R.S. Sparkes, Haplotypes at the DRD2 locus and severe alcoholism, Am. J. Med. Genet. 96 (2000) 622–631. U.W. Preuss, P. Zill, G. Koller, B. Bondy, M. Sokya, D2 dopamine receptor gene haplotypes and their influence on alcohol and tobacco consumption magnitude in alcohol-dependent individuals, Alcohol Alcohol 42 (2007) 258–266. Y. Kono, H. Yoneda, T. Sakai, Y. Nonomura, Y. Inayama, J. Koh, J. Sakai, Y. Inada, H. Imamichi, H. Asaba, Association between earlyonset alcoholism and the dopamine D2 receptor gene, Am. J. Med. Genet. 74 (1997) 179–182. G. Ponce, M.A. Jimenez-Arriero, G. Rubio, J. Hoenicka, I. Ampuero, J.A. Ramos, T. Palomo, The A1 allele of the DRD2 gene (TaqI A polymorphisms) is associated with antisocial personality in a sample of alcohol-dependent patients, Eur. Psychiatry 18 (2003) 356–360. B.R. Lawford, R. Young, E.P. Noble, B. Kann, T. Ritchie, The D2 dopamine receptor (DRD2) gene is associated with co-morbid

595

depression, anxiety and social dysfunction in untreated veterans with post-traumatic stress disorder, Eur. Psychiatry 21 (2006) 180–185. [28] R.M. Young, B.R. Lawford, E.P. Noble, B. Kann, A. Wilkie, T. Ritchie, L. Arnold, S. Shadforth, Harmful drinking in military veterans with post-traumatic stress disorder: association with the D2 dopamine receptor A1 allele, Alcohol Alcohol 37 (2002) 451–456. [29] A. Serretti, F. Macciardi, C. Cusin, E. Lattuada, D. Souery, O. Lipp, B. Mahieu, C. Van Broeckhoven, D. Blackwood, W. Muir, H.N. Aschauer, A.M. Heiden, M. Ackenheil, S. Fuchshuber, P. Raeymaekers, G. Verheyen, R. Kaneva, A. Jablensky, G.N. Papadimitriou, D.G. Dikeos, C.N. Stefanis, E. Smeraldi, J. Mendlewicz, Linkage of mood disorders with D2, D3 and TH genes: a multicenter study, J. Affect. Disord. 58 (2000) 51–61. [30] S.Y. Huang, W.W. Lin, F.J. Wan, A.J. Chang, H.C. Ko, T.J. Wang, P.L. Wu, R.B. Lu, Monoamine oxidase-A polymorphisms might modify the association between the dopamine D2 receptor gene and alcohol dependence, J. Psychiatry Neurosci. 32 (2007) 185–192.