Sunlight Could Be a Geographic Risk Factor for Pediatric-Onset Bipolar Disorder
A number of factors appear to be associated with age of onset of bipolar disorder. Several studies have replicated the finding that those who experienced some adversity in childhood and who have a parent or parents with bipolar disorder are at increased risk for earlier onset of the illness. These risk factors are more prevalent in the US than in many western European countries, and considerable data support the observation that the age of onset of bipolar illness is earlier in the United States than in several European countries. However, childhood onsets of the illness are prevalent in Turkey and in Norway.
Researcher Mike Bauer raises another possibility in an abstract presented at the 5th Biennial Conference of the International Society for Bipolar Disorders. He examined the association between age of onset and sunlight in the environment in 24 different sites in 13 different countries. Solar insolation refers to the amount of electromagnetic energy striking the surface of the earth. Bauer found that larger springtime maximum monthly increases in solar insolation were associated with younger ages of onset of bipolar disorder (p= 0.006). These calculations were derived from NASA Surface Meteorology and Solar Energy databases for each location. The largest maximum monthly increases in solar insolation occurred in varied climates, including in Norway, Chile, and arid parts of California.
