Multidisciplinary contributions towards an evolutive interpretation of bipolar disorders: could it be the pathological drift of a potentially adaptive condition?

This paper tries to summarize the results of studies from different areas of knowledge supporting the idea that temperamental traits, such as “reckless/hyper-exploratory” attitudes, commonly believed to be associated with psychopathology, surprisingly turn out as adaptive under specific stress conditions. In particular, this paper analyzes an ethologic line of research on primates suggesting models for a sociobiological interpretation of mood disorders in humans; a study that found high frequencies of a genetic variance associated with bipolar disorder in people without bipolar disorder but with hyperactivity/novelty-seeking traits; the outcomes of socio-anthropological-historical surveys on the evolution of mood disorders in Western countries in the last centuries; surveys on changing societies in Africa and African migrants in Sardinia; and studies that found higher frequencies of mania and subthreshold mania among Sardinian immigrants in Latin American megacities. Although it is not unequivocally accepted that the prevalence of mood disorders has increased, it would be logical to suppose that a nonadaptive condition should have disappeared over time; mood disorders, on the contrary, persist and their prevalence might have even increased. This new interpretation could lead to counter discrimination and stigma towards people suffering from the disorder and would be a central point in psychosocial treatments in addition to pharmacological therapy. Our aim is to hypothesize that bipolar disorder, strongly characterized by these traits, may be the result of the interaction between genetic characteristics, not necessarily pathological, and specific environmental conditions rather than a mere product of an aberrant genetic profile. If mood disorders were mere nonadaptive conditions, they would have disappeared over time; however, their prevalence paradoxically persists if not even increases over time. The hypothesis that bipolar disorder may result from the interaction between genetic characteristics, not necessarily pathological, and specific environmental factors seems more credible than considering bipolar disorder as a mere product of an aberrant genetic profile.