The use of betel nut and other psychoactive substances, and their effects on the symptoms of people with schizophrenia in Palau, Micronesia

Abstract

The use of betel nut and other psychoactive substances, and their effects on the symptoms of people with schizophrenia in Palau, Micronesia: A biocultural perspective. Key words: Adaptation; Alcohol; Anthropology; Areca; Arecoline; Cannabis; Cross-cultural; Ecology; Evolution; Psychiatry; Psychology; Reward; Self-medication; Substance-use; Tobacco. The expression of schizophrenia in North American and European settings is characterized by a high prevalence of non-prescribed substance use. This study has sought to ascertain whether extraordinary substance use also occurs in other societies. Patterns of substance use and the effects of substances on the symptoms of 70 people diagnosed with schizophrenia were assessed in a non-western location, namely, the Republic of Palau, Micronesia. Symptoms of schizophrenia and associated movement disorders were measured using the Positive and Negative Syndrome Scale and the Extrapyramidal Symptom Rating Scale, respectively. The study participants' own perspectives of the effects of substance use were also considered. In the study population, use of the indigenous drug, betel nut(Areca catechu),was associated with significantly milder symptoms of schizophrenia. In contrast, tobacco smoking was associated with significantly increased symptom severity. Female and male study participants consumed both betel nut and tobacco, but consumption of alcohol and cannabis was almost exclusively a male activity. Male cannabis and alcohol use was associated with significantly reduced negative symptoms and/or depression. As group, the study participants' symptomatology, course of illness, and substance-using behaviours were similar to those observed in people with schizopherenia in North American and European settings. Cross-cultural substance-use patterns included gender differences, a high overall prevalence of substance use, and an association between male substance abuse and a history of violence. The study results were interpreted as providing cross-cultural support for the hypothesis that people with schizophrenia use substances to self-medicate their symptoms. The Palauan study participants also displayed cultural particularities. By international standards, they were well educated, well travelled, and a high proportion lived with their families. Also distinctive to the Palauan study group were a low prevalence of female substance use, a high female fertility rate a low prevalence of tardive dyskinesia, a high overall prevalence of schizophrenia, and a markedly higher rate of schizophrenia diagnoses among males. Evidence of extraordinary substance use and/or self-medication by people with schizophrenia across cultures was interpreted from the perspective of three evolutionary models: people with schizophrenia principally use drugs (1) because substance use is a contextually adaptive strategy (2) because of a biological vulnerability to drug-induced reward and reinforcement (3) because substance-using behaviour is functionally-organised by evolved psychological mechanisms.