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The evolutionary significance of depression in Pathogen Host Defense (PATHOS-D)
1Department of Psychiatry, College of Medicine, University of Arizona, Tucson, AZ 85724-5137, USA. craison@medadmin.arizona.edu
Molecular Psychiatry
|February 1, 2012
Summary
Depression risk alleles persist because they aid pathogen host defense, not social function. This Pathogen Host Defense (PATHOS-D) hypothesis explains their prevalence despite social impairments.
Area of Science:
- Evolutionary biology
- Genetics
- Psychiatry
Background:
- Depression impairs fitness, yet risk alleles persist in the human genome.
- Existing evolutionary theories inadequately explain this persistence.
Purpose of the Study:
- To investigate the hypothesis that depression risk alleles are maintained due to their role in pathogen host defense.
Main Methods:
- Literature review of studies on depression risk alleles using PubMed and Ovid MEDLINE.
- Examination of data linking genetic risk factors to immune responses and infection defense.
Main Results:
- Depression risk alleles are associated with immune responses enhancing ancestral survival.
- Specific depressive symptoms (e.g., fever, withdrawal, anorexia) support pathogen defense.
Conclusions:
- The Pathogen Host Defense (PATHOS-D) hypothesis offers a novel explanation for depression risk allele prevalence.
- Alleles may be adaptive against pathogens, despite being nonadaptive in social contexts.
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