Evidence that anhedonia is a symptom of opioid dependence associated with recent use.

Background: Anhedonia is prevalent among substance-dependent populations. The hedonic allostasis model suggests this is due to the effects of addictive substances on neural substrates of reward processing. However, previous research may have been confounded by other factors likely to influence anhedonia, including tobacco use, psychopathology, and history of trauma and other stressors. Thus it remains unclear whether elevated anhedonia in substance-dependent populations is caused by substance use itself, or is due to other correlates of substance dependence.
Methods: Multivariate analysis of covariance was conducted to test whether opioid-dependent participants' anhedonia scores were elevated, relative to a non-dependent control group, after controlling for psychosocial factors likely to influence anhedonia. Correlational analyses within opioid-dependent participants were also conducted to examine whether anhedonia was associated with recent illicit opioid use or duration of abstinence.
Results: There was a modest, but significant, elevation in anhedonia in opioid-dependent participants, relative to controls (Partial η ² =0.034, p=0.041) after controlling for psychosocial variables that were associated with anhedonia. Depressive symptoms and history of post-traumatic stress disorder also remained significantly associated with anhedonia in the adjusted model. Among participants on opioid pharmacotherapy, there were significant associations between frequency of recent illicit opioid use and scores on anhedonia measures (all r _s >0.25, p<0.013), but among abstinent opioid-dependent participants, relationships between duration of abstinence and anhedonia were not significant (all r _s <0.24, p>0.22).
Conclusion: These findings support the hypothesis that use of opioids can cause anhedonia, although other psychosocial factors may also contribute to the high prevalence of anhedonia among opioid-dependent populations.
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