EPA-1065 – There is a Method in Madness: are Affective Disorders and Affective Temperaments Evolutionally Adaptive?

Abstract

In spite of the great burden and adaptive disadvantage associated with them, psychiatric illnesses do not become extinct over time with evolution. The most investigated and accepted explanation for this is that the genes encoding for risk of psychiatric illnesses also encode for traits determining greater adaptational and evolutionary success, most observable in healthy first degree relatives of psychiatric patients, sharing overlapping genotypes and exhibiting attenuated manifestations of the relevant endophenotypes. Besides the burden associated with affective illness, the advantage of genes and related (endo)phenotypes is observable on the individual and group/social level aiding several aspects of survival and reproduction. In order to gain deeper insight into the advantageous and disadvantageous sides of mood disorders as distinct integral entities, decomposing these illnesses into smaller and more easily characterizable phenomena such as their affective temperamental bases may reveal how these disorders carry multiple possibly adaptive aspects. Furthermore, in a recent paper, a parallel pattern of distribution was found between the relative frequency of certain dominant affective temperaments and relative scores on Hofstede's cultural indexes investigating data from six countries. Matching distributions for scores were identified for depressive temperament and individualism-collectivism, hyperthymic temperament and uncertainty avoidance, and irritable temperament and power distance. These findings indicate an important relationship between affective temperaments and cultural dimensions, suggesting that these phenomena may be the manifestations of the same genetically determined predispositions in different forms, and that affective temperaments, also considered the precursors of affective illness, play a role on social-cultural evolution and adaptation as well.