1. ¹Division of Psychobiology, Tokyo Institute of Psychiatry, Tokyo, Japan
2. ²Laboratory of Neuropharmacology, Department of Pharmaceutical Sciences, Hiroshima International University, Kure, Japan
3. ³Department of Molecular Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
4. ⁴Department of Psychobiology, Tohoku University Graduate School of Medicine, Sendai, Japan
5. ⁵Department of Neuropsychiatry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
6. ⁶Department of Psychiatry, Nagoya University Graduate School of Medicine, Nagoya, Japan
7. ⁷Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, Hamamatsu, Japan
8. ⁸Department of Psychiatry, Teikyo University, School of Medicine, Ichihara Hospital, Chiba, Japan
9. ⁹Department of Neuropsychiatry, Kurume University School of Medicine, Kurume, Japan
10. ¹⁰Division of Psychiatry, National Center Hospital for Mental, Nervous and Muscular Disorders, National Center of Neurology and Psychiatry, Tokyo, Japan
11. ¹¹Department of Psychogeriatrics, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo, Japan
12. ¹²Department of Psychiatry, Graduate School of Medicine, Chiba University, Chiba, Japan
13. ¹³Department of Psychiatry, Fujita Health University School of Medicine, Aichi, Japan
14. ¹⁴Health Administration Center, Azabu University, Kanagawa, Japan
15. ¹⁵Schizophrenia Research Project, Tokyo Institute of Psychiatry, Tokyo, Japan
16. ¹⁶Department of Pharmacology, Hokkaido University Graduate School of Pharmaceutical Sciences, Sapporo, Japan
17. ¹⁷Japanese Genetics Initiative for Drug Abuse (JGIDA), Japan

Correspondence: Dr I Sora, Department of Psychobiology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan. E-mail: isora@mail.tains.tohoku.ac.jp

Received 27 June 2005; Revised 24 October 2005; Accepted 26 October 2005; Published online 10 January 2006.

Abstract

Several studies indicate that the -opioid receptor plays a role in addiction not only to opiate drugs but also to alcohol and non-opiate addictive drugs. Our studies aim to reveal the associations between gene polymorphisms and methamphetamine (MAP) dependence/psychosis. We newly identified several polymorphisms and four substantial linkage disequilibrium (LD) blocks in the -opioid receptor (OPRM1) gene. We found significant differences in both genotype and allele frequencies of the single-nucleotide polymorphism (SNP) IVS2+G691C between control (n=232) and MAP-dependent/psychotic patients (n=128). There was also a significant association between IVS2+G691C and patients with transient psychosis. These results suggest that the OPRM1 gene variations may be a factor in development and prognosis of MAP psychosis.