The Depressed Brain: An Evolutionary Systems Theory.
Major depression is a debilitating condition characterised by diverse neurocognitive and behavioural deficits. Nevertheless, our species-typical capacity for depressed mood implies that it serves an adaptive function. Here we apply an interdisciplinary theory of brain function to explain depressed mood and its clinical manifestations. Combining insights from the free-energy principle (FEP) with evolutionary theorising in psychology, we argue that depression reflects an adaptive response to perceived threats of aversive social outcomes (e.g., exclusion) that minimises the likelihood of surprising interpersonal exchanges (i.e., those with unpredictable outcomes). We suggest that psychopathology typically arises from ineffectual attempts to alleviate interpersonal difficulties and/or hyper-reactive neurobiological responses to social stress (i.e., uncertainty), which often stems from early experience that social uncertainty is difficult to resolve.
Centre for Youth Mental Health, The University of Melbourne, Melbourne, VIC 3052, Australia; Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, VIC 3010, Australia; Orygen, The National Centre of Excellence in Youth Mental Health, Melbourne, VIC 3052, Australia. Electronic address: pbadcock@unimelb.edu.au.
Paul B
PB
Badcock
Centre for Youth Mental Health, The University of Melbourne, Melbourne, VIC 3052, Australia; Orygen, The National Centre of Excellence in Youth Mental Health, Melbourne, VIC 3052, Australia.
Christopher G
CG
Davey
Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, VIC 3010, Australia; Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Melbourne, VIC 3053, Australia.
Sarah
S
Whittle
Department of Psychology, University of Oregon, Eugene, OR 97403, USA.
Nicholas B
NB
Allen
Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, UK; Senior author.
Karl J
KJ
Friston
D005075:Biological Evolution; D001921:Brain / Q000502:physiology*; D003863:Depression / Q000503:physiopathology*; D003865:Major Depressive Disorder; D013598:Systems Theory