Incidence of psychiatric disorders after extended residence in Antarctica

The incidence of psychiatric disorders and depressive symptoms was examined in a cohort of American men and women who spent an austral winter at two different research stations in Antarctica to determine whether extended residence of nonindigenous inhabitants in a polar region is associated with psychiatric morbidity.

Debriefings interviews with 220 men and 93 women were conducted by 3 psychiatrists and 1 clinical psychologist at McMurdo Station and South Pole Station at the end of the austral winter between 1994 and 1997. Crewmembers were assigned a DSM-IV diagnosis if they satisfied diagnostic criteria. Debriefed crewmembers also completed the Structured Interview Guide for the Hamilton Depression Inventory-Seasonal Affective Disorders version (SIGH-SAD).

Thirty-nine (12.5%) crewmembers presented with symptoms that met the criteria for one or more DSM-IV disorders. After weighting the prevalence to account for the low participation rate of civilian personnel, the incidence of DSM-IV disorders was 5.2%. Mood disorders were the most common diagnoses, accounting for 30.2% of all diagnoses, followed by adjustment disorders (27.9%), sleep-related disorders (20.9%), personality disorders (11.6%), and substance-related disorders (9.3%). Depressive symptoms as measured by the SAD-SIGH were significantly associated with female gender, military occupation, station, year of expedition, and DSM-IV diagnosis.

Differences in the distribution of symptoms and diagnoses by demographic and expedition characteristics suggests that the social environment may be a more powerful determinant than the physical environment of psychiatric disorders in a polar region.