Psychological Distress and Cognitive Function in Women: Exploring Potential Mediation by Use of Opiates, Sleep Aids, or Minor Tranquilizers

<b><i>Objectives:</i></b> Distress, including posttraumatic stress disorder (PTSD) and depression, is associated with lower cognitive function and higher use of medications, including sleep aids, opiate pain relievers, and minor tranquilizers. Whether use of these medications is linked to lower cognitive function, and whether such medication use might partially explain the relationship between distress and cognition remains unclear. Using data from 10,653 women in the Nurses' Health Study II, we assessed associations between distress and past-month medication use; medication use and cognitive function; and whether medication use mediates the distress-cognitive function relationship. <b><i>Methods:</i></b> Distress was defined using validated measures of PTSD and depression. To consider possible joint effects of experiencing both forms of distress, we derived a continuous, standardized distress score including symptoms of both PTSD and depression, and a six-level categorical variable indicating the presence/absence of trauma, PTSD, and depression. Past-month medication use was self-reported. Cognitive function was measured with the Cogstate Brief Battery, yielding composite score measures of psychomotor speed/attention and learning/working memory. We fit linear regression models for continuous outcomes, logistic regression for dichotomous outcomes, and conducted causal mediation analysis using a counterfactual framework. <b><i>Results:</i></b> Higher distress was associated with use of all three medications (e.g., a 1-standard-deviation higher continuous distress score was associated with 1.5 times the adjusted odds of past-month opiate use [95% confidence interval: 1.40, 1.60]). Associations between past-month medication use and cognitive function were mixed. <b><i>Conclusion:</i></b> We did not find clear evidence of mediation by medication use, suggesting that distress may influence cognitive function <i>via</i> other pathways.