Research paperUric acid in major depressive and anxiety disorders

- Uric acid is neuroprotective owing to its antioxidant properties.
- Plasma uric acid levels are lower in current major depressive and anxiety disorders.
- Plasma uric acid levels are negatively associated with symptom severity and duration.
- Lowered antioxidant status may play a role in affective disorders.

BackgroundUric acid has neuroprotective effects, owing to its antioxidant properties. Lowered antioxidant capacity, causing increased oxidative stress, may be involved in affective disorders and might be altered by antidepressants. This study investigated the association of plasma uric acid, the greatest contributor to blood antioxidant capacity, with major depressive disorder (MDD) and anxiety disorders.MethodsData were from the Netherlands Study of Depression and Anxiety including patients with current (N = 1648), remitted (N = 609) MDD and/or anxiety disorders (of which N = 710 antidepressant users) and 618 controls. Diagnoses were established with the Composite International Diagnostic Interview. Symptom severity was assessed with the Inventory of Depressive Symptoms-Self Report, Beck Anxiety Inventory and Fear Questionnaire. Uric acid was measured in plasma. Analyses were adjusted for sociodemographic, health and lifestyle variables.ResultsPlasma uric acid adjusted mean levels were lower in current MDD and/or anxiety disorder(s) (289 μmol/l) compared to remitted disorders (298 μmol/l, p < .001) and controls (299 μmol/l, p < .001; Cohen's d .10). This finding was independent of antidepressant use. Depressive (β-.05, p = .0012), anxiety (β-.04, p = .009) and phobic (β-.03, p = .036) symptom severity, and symptom duration (β-.04, p = .009) were negatively associated with uric acid.LimitationsLimitations include the lack of data on dietary intake which could be a potential confounding factor. From these cross-sectional findings, the association between uric acid and psychopathology cannot be inferred to be causal.ConclusionThis large scale study finds plasma uric acid levels are lower in current, but not remitted, MDD and/or anxiety disorders, according to a dose-response gradient. This suggests the involvement of decreased antioxidant status in affective disorders, and points to their potential as an avenue for treatment.