Is low mood an adaptation? Evidence for subtypes with symptoms that match precipitants

Abstract

Background: Although severe depression is dysfunctional, the capacity to experience normal low mood may be useful in certain fitness-threatening situations. Moreover, if specific kinds of situations recurred often enough in the course of evolution, natural selection may have shaped partially differentiated subtypes of low mood that are parallel to the subtypes of anxiety that protect against different kinds of danger. To test this hypothesis, we examined how symptoms of low mood differ depending upon the precipitating situation, and whether these differences match expectations of symptoms useful in each kind of situation. Method: 337 subjects who experienced a period of low mood within the last year wrote accounts describing perceived causes of their low mood and they filled out the CES-D depression inventory. Seven symptom scales were derived from analysis of CES-D data. Independent judges blindly coded the accounts into one of six precipitant categories. Results: Different untoward situations were associated with different symptoms that were predicted to be useful in those situations. Social losses (death of a loved one, romantic breakups, and social isolation) were associated with greater crying and arousal. Failure to reach a goal, stress, and winter seasons were associated with more fatigue and pessimism. Discussion: These results suggest that natural selection shaped not only a generic state of low mood but also partially differentiated subtypes shaped to cope with specific situations that were associated with fitness losses among our ancestors. D

Autonomic aspect of emotional response in depressed patients: Relationships with personality

“…As well, when BIS-related dimensions were controlled, the influence of depression on arousal disappears, suggesting that these personality dimensions are involved in the global lowering of self-reported emotion intensity observed in depression. According to ECI hypothesis, depression (depressive mood) could be a global defensive insensitization to the whole environment that might be adaptive while allowing the individual to disengage from situations where it would be useless or dangerous to keep on acting (e.g., inaccessible goals [29,38]). To this view, it is consistent that this supposed-defensive aspect of depression might be related to other defensive phenomena potentiation, such as behavioral inhibition tendencies as measured by the BIS-related personality scores.…”

Major-Minor Tonality, Schenkerian Prolongation, and Emotion: A commentary on Huron and Davis (2012)

“…Independent of music, sadness is associated with uncertainty. Different negative moods have different functions, suggesting different evolutionary origins (Keller & Nesse, 2005): grief (exhibited as sadness and crying) has a social function of strengthening social ties to replace lost ones, while the sadness that is associated with fatigue or pessimism may have the function of conserving energy-for example, during the winter, or more generally while waiting for a new opportunity for effective action. In any case, sadness slows people down, which gives them time to think about and evaluate options in uncertain situations.…”

An evolutionary model of low mood states

“…Thus, the adaptive approach helps explain why there might be states such as dysphoric mania, which seem like depression in some ways and like good mood in others. More generally, evolutionary reasoning 13 helps explain the situation-specific diversity of human emotional responses (Keller and Nesse, 2005;Keller and Nesse, 2006;Nesse, 1990).…”