First episode of psychosis in Guam: The role of ethnicity and neighbourhood factors.

Abstract

Ethnicity, neighbourhood ethnic density, and four additional neighbourhood factors (urbanicity, crime, voting, and poverty) were examined in relation to the incidence of first episode of psychosis (FEP) in the Pacific Island of Guam. All first contact patients seen at the Guam Department of Mental Health and Substance Abuse (DMHSA) between January 2005 and December 2007 that met DSM-IV criteria for the diagnosis of a psychotic disorder were included. At the time of the study, DMHSA was the only psychiatric facility in Guam. After controlling for age and gender, Chamorros, the indigenous people of Guam, had a standardized incidence rate (IR=151/100 000 person-years, 95%CI=129-173) of FEP over twice that of Whites (IR=66/100 000 person-years, 95%CI=34-99). Individuals from Palau had the highest standardized incidence rate (IR=832/100 000 person-years, 95%CI=581-1083). Increased neighbourhood Chamorro density was associated with decreased incidence of FEP among Chamorro individuals (IRR=0.11, 95%CI=0.03-0.43). After controlling for age, gender, ethnicity, and other neighbourhood factors, urbanicity (IRR=3.82, 95%CI=1.86-7.81), voting (IRR=2.06, 95%CI=1.32-3.20), poverty (IRR=1.94, 95%CI=1.40-2.67), and crime (IRR=1.18, 95%CI=1.00-1.40) remained statistically associated with FEP incidence. The findings add to prior research that suggests that rates of mental health problems are higher in indigenous than in settler communities and are highest for indigenous people who live in neighbourhoods with few other indigenous individuals. Findings also suggest that even on a small island, with only ~150 000 people, urbanicity is associated with FEP. Finally, results are consistent with other research suggesting that the reduction of crime and social adversity can play a positive role in reducing the incidence of first episode psychosis.