Reaction Time in Adolescence, Cumulative Allostatic Load, and Symptoms of Anxiety and Depression in Adulthood: The West of Scotland Twenty-07 Study

OBJECTIVE: To examine the relation between reaction time in adolescence and subsequent symptoms of anxiety and depression and investigate the mediating role of sociodemographic measures, health behaviors, and allostatic load. METHODS: Participants were 705 members of the West of Scotland Twenty-07 Study. Choice reaction time was measured at age 16. At age 36 years, anxiety and depression were assessed with the 12-item General Health Questionnaire (GHQ) and the Hospital Anxiety and Depression Scale (HADS), and measurements were made of blood pressure, pulse rate, waist-to-hip ratio, and total and high-density lipoprotein cholesterol, C-reactive protein, albumin, and glycosolated hemoglobin from which allostatic load was calculated. RESULTS: In unadjusted models, longer choice reaction time at age 16 years was positively associated with symptoms of anxiety and depression at age 36 years: for a standard deviation increment in choice reaction time, regression coefficients (95% confidence intervals) for logged GHQ score, and square-root–transformed HADS anxiety and depression scores were 0.048 (0.016–0.080), 0.064 (0.009–0.118), and 0.097 (0.032–0.163) respectively. Adjustment for sex, parental social class, GHQ score at age 16 years, health behaviors at age 36 years and allostatic load had little attenuating effect on the association between reaction time and GHQ score, but weakened those between reaction time and the HADS subscales. Part of the effect of reaction time on depression was mediated through allostatic load; this mediating role was of borderline significance after adjustment. CONCLUSIONS: Adolescents with slower processing speed may be at increased risk for anxiety and depression. Cumulative allostatic load may partially mediate the relation between processing speed and depression.