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Revisiting the serotonin-aggression relation in humans: a meta-analysis
Aaron A Duke1, Laurent Bègue, Rob Bell
1Interuniversity Laboratory of Psychology.
Psychological Bulletin
|February 6, 2013
Summary
The serotonin deficiency hypothesis of aggression is weakly supported by evidence. A meta-analysis found a small inverse correlation between serotonin and aggression, with inconsistent results across studies.
Area of Science:
- Neuroscience
- Psychology
- Psychopharmacology
Background:
- The serotonin deficiency hypothesis of human aggression is widely accepted but faces challenges from conflicting research.
- Decades of studies have yielded inconsistent findings regarding the relationship between serotonin and aggression.
- Methodological limitations in existing research complicate the interpretation of serotonin's role in aggression.
Purpose of the Study:
- To systematically review and meta-analyze evidence for and against the serotonin deficiency hypothesis of human aggression.
- To evaluate the relationship between serotonin functioning and aggression using diverse assessment methods.
Main Methods:
- Systematic review and meta-analysis of 175 independent samples (over 6,500 participants).
- Assessment of serotonin functioning via cerebrospinal fluid 5-hydroxyindoleacetic acid (CSF 5-HIAA), acute tryptophan depletion, pharmacological challenge, and endocrine challenge.
- Analysis of aggression, anger, and hostility using self-report and other-report measures.
Main Results:
- An aggregate small, inverse correlation (r = -.12) between serotonin functioning and aggression, anger, and hostility was found.
- Pharmacological challenge studies showed the largest effect size (r = -.21), while CSF 5-HIAA studies showed the smallest (r = -.06).
- Effect sizes diminished over time, and other-reported aggression positively correlated with serotonin functioning, contrary to self-reports.
Conclusions:
- The serotonin deficiency hypothesis is not robustly supported by the aggregated evidence.
- Methodological factors, including measurement reliability and reporting biases, likely influence study outcomes.
- Future research should refine measures, explore interactions, and revise the hypothesis to reflect serotonin's complex functions.
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