FROM MEDICAL HYPOTHESES

Persons who committed suicide and lived at higher altitudes were significantly more likely to have bipolar disorder, compared with depression, schizophrenia, or anxiety disorders, researchers reported in the April issue of Medical Hypotheses.

Past research has found an association between altitude and suicide, even after controlling for gun ownership, rurality, age, and mental health access. The current study indicates that altitude preferentially affects suicide in bipolar disorder, said Rebekah S. Huber, a researcher at the University of Utah Brain Institute, Salt Lake City, and her as- I sociates.

The researchers performed random coefficient logistic regression modeling and least squares means on data for 35,725 suicides in 16 states and 809 counties that occurred during 2005-2008 and were reported to the Centers for Disease Control and Prevention's National Violent Death Reporting System. The investigators assigned every decedent a single major diagnosis of bipolar disorder, major depressive disorder, schizophrenia, or anxiety disorder, and excluded infrequent diagnoses such as posttraumatic stress disorder or eating disorder.

Living at higher altitude was significantly associated with having bipolar disorder instead of another mental health diagnosis in both random coefficient (P = 0.004) and logistic (P = 0.001) regression models. Persons with bipolar disorder committed suicide at a higher mean altitude (1,205 meters) than did decedents with anxiety disorders (1,181), major depressive disorder (1,116), or schizophrenia (1,057). …