Does latitude as a zeitgeber affect the course of bipolar affective disorder?

Bipolar disorder in Asia: Illness course and contributing factors

“…Such vulnerability has been indicated in increased frequency of manic episodes in those regions compared to frequent depressive episodes reported elsewhere (Bauer et al, 2014;Kohno et al, 2012;Lee et al, 2002;Narayanaswamy et al, 2014;Osher et al, 2000). When BD-II with seasonal course pattern is considered, the higher number of depressive recurrences is in line with similar studies reported elsewhere (Geoffroy et al, 2014;Goikolea et al, 2007).…”

Long term course of bipolar I disorder in India: Using retrospective life chart method

“…and other tropical areas such as Nigeria (Makanjuola, 1985). These differences have been reviewed and hypothesized by Narayanaswamy et al, 2014 to be due to the effect of latitude as a zeitgeber in bipolar disorder. In contrast, data from the temperate regions (Judd et al, 2002;Perugi et al, 2000) points to a greater time spent in the depressive phase.…”

“…Firstly, it may reflect actual differences in the occurrence of the type of episodes in different regions of the world. The zeitgeber effect has been proposed as an explanation for the increase in manic polarity of bipolar illness as we move towards lower equatorial latitudes (Narayanaswamy et al, 2014). Secondly, such a finding may also arise due to proclivity of the patients and their family members towards recollecting disruptive manic episodes.…”

“…This estimate translates to a patient load of about 0.2 million individuals with bipolar I disorder. It has recently been suggested that the course of bipolar disorder may be different in tropical countries like India with a preponderance of manic episodes (Narayanaswamy et al, 2014), as compared to the temperate developed nations from where the majority of the published literature on bipolar disorder has emerged. If such differences in the types of episodes exist, they would have contextual implications in the management and service delivery focus of this vast patient population.…”

Gender Differences in the 5 Years Course of Bipolar Disorder after a First Manic Episode: A Retrospective Review

“…The available course and outcome studies have documented a preponderance of manic episodes and onset of BD with mania. [ 5 6 7 ] Median time to recurrence is reportedly shorter in females. Both studies have highlighted that the course of BD in India may be different from what has been reported from the west.…”