Since the inception of the modern era of psychopharmacology, psychotropics have been the mainstay of the care of psychiatric patients all over the world, irrespective of their cultural and ethnic backgrounds. Until recently, however, variations in treatment response across populations, including effectiveness, dosing strategies, and adverse-effect profiles, have received minimal attention.1,2
Psychopharmacological research in general and randomized controlled trials in particular have been conducted largely in North America and Western Europe and have rarely included persons of ethnic minority or cross-cultural backgrounds.3 This, in part, reflects the asymmetrical distribution of resources and the “Eurocentric” slant of the research establishment. Responsibility for such biases also lies in deeply rooted beliefs and assumptions that suggest that treatment responses are predominantly determined by biological mechanisms and that biological processes are universally applicable and thus color- and culture-free.
In contrast, there have been remarkable changes in the past 3 decades in the documentation of often substantial variations in drug responses across cultural and ethnic groups and in the delineation of mechanisms responsible for the variations.4,5 These findings have profound clinical and theoretical import, and it is important that they not be simplistically interpreted. As is true with all social and biological phenomena (eg, height, weight, temperament, child-rearing practices), drug response characteristics are normally distributed so that between-group differences are always accompanied by overlaps at the individual level.
Remarkable interindividual and intracultural variations coexist with ethnic/cultural differences. That is, while the majority of members of a population group fall on one side of the distribution, and those of another group on the other side, there are always exceptions. Neglect of such overlaps may lead to overgeneralization of research findings, which, in turn, could contribute to cultural stereotyping and consequent stigmatization.
For example, there are substantive ethnic variations in haloperidol(Drug information on haloperidol) metabolism between Asians and whites.6 At the same time, equally extensive interindividual variations within each of the ethnic groups also have been seen, resulting in significant overlap between the two groups.
This article reviews the cultural and biological aspects of drug effects and the role of interindividual, cross-ethnic, and genetic variations as well as environmental factors on treatment response.
Cultural aspects of drug effects
For the purposes of clarity in discussion, materials and opinions included in this article are presented with concepts that are commonly regarded as dichotomous, such as culture and biology, as well as the “instrumental” versus “symbolic” aspects of pharmacological responses. In reality, increasing evidence indicates that such divisions are artificial and potentially misleading. In many instances, culture and biology clearly interact with and influence each other, as do medications’ “instrumental” (biological, pharmacological) and “symbolic” (nonbiological) effects. For example, drug-induced sedation may be regarded by one patient as a positive sign that suggests that the medication is beginning to work. For another patient, it may be an alarming sign of symptomatic worsening or a harbinger of medication toxicity. Such interpretations, based on individual beliefs that have been shaped largely by cultural and personal backgrounds, serve to further influence subsequent treatment response.