Methamphetamine in Japan: the consequences of methamphetamine abuse as a function of route of administration

To determine differences in life backgrounds and clinical features between methamphetamine (MAP) smokers and injectors in Japan.

Out-patient clinic at a psychiatric centre.

Among 451 MAP abusers undergoing initial assessments, 116 subjects whom the first author had directly interviewed and treated were studied.

In this study, life backgrounds, clinical features and psychiatric symptoms were compared between three subgroups: 42 (36.2%) in group S (smoking only); 57 (49.1%) in group I (injection only); and 17 (14.7%) in group SI (initially smoking, later injecting).

Group I more often had parental absence (P < 0.001), a family history of alcoholism (P < 0.05), limited education (P < 0.001), or a criminal record (P < 0.001) than patients in the other two groups. Group S had the most cannabis use (P < 0.01), while group I had the most volatile solvents use (P < 0.01). Group S experienced their first psychotic episode sooner after first MAP use (P < 0.01), but showed fewer auditory hallucinations at initial assessment than patients in other groups (P < 0.001). Group SI was intermediate between groups S and I in life background, clinical features and psychotic symptoms, while they had lost control of their drug use most frequently (P < 0.02).

In Japan, MAP smokers have different life backgrounds from injectors. Smoking MAP does not appear to be a safer route as regards losing control of MAP use and inducing psychosis than injection.