Research by the World Health Organization (WHO) has suggested that the course and symptomatic expression of schizophrenia is relatively more benign in developing societies.

However, a new study from Current Anthropology challenges this assumption, comparing biological and cultural indicators of schizophrenia in urban, Western societies with study data from the island of Palau, which has one of the highest rates of schizophrenia diagnosis in the world today.

"A 1% average worldwide population prevalence of schizophrenia is routinely interpreted in the medical literature as implying a uniform distribution," write Roger J. Sullivan (California State University, Sacramento), John S. Allen (University of Southern California), and Karen L. Nero (University of Canterbury, New Zealand). "In this sense, the 1% figure is a myth that conceals considerable variability in actual prevalence between settings."

The researchers point to the islands in Micronesia as an example of this variation. Prevalence of schizophrenia ranges from a low of 0.4% in the Marshall Islands to 1.7% in the western Republic of Palau -- a more than fourfold difference. The expression of schizophrenia in Palau and greater Micronesia is also extraordinarily gendered, with rates of affliction approximately two times higher among males than among females.

"Recognizing this high variability in prevalence between populations is important," write the researchers, ". . . Genetic perspectives tend to emphasize uniformity in prevalence and symptomatic expression while contextual sociocultural perspectives tend to emphasize variability."

The authors combined quantitative clinical diagnostic tools -- of symptoms like poor impulse control and eye-tracking -- with qualitative methods such as patient interviews. Compared to a sample of New Yorkers and other similar studies in New Zealand and Scotland, their findings challenge the idea put forth by the WHO and other research that schizophrenia in developing regions is distinct from and more benign than schizophrenia in developed regions.

The researchers also dispute the common assumption that schizophrenia in developing nations is a consequence of development.

"These analyses have identified unique aspects of the expression of schizophrenia in Palau, but more striking to us are the similarities that emerge when comparing the Palauan data with research findings in [Western] settings," the authors write.

Indeed, one of the few significant differences between the Palauan sample and the Western sample was the proportion of participants living at home. (Eighty-seven percent of the Palauan participants lived at home.) Notably, "extensive kin-based levels of support" have been cited by the WHO to explain the supposedly more benign expression of schizophrenia in developing regions.

Reference: Sullivan, Roger J., John S. Allen, and Karen L. Nero, "Schizophrenia in Palau: A Biocultural Analysis." Current Anthropology 48:2.