Anti-depressant medication use and C-reactive protein: Results from two population-based studies

The use of anti-depressant medication has been linked to cardiovascular disease (CVD). We examined the association between anti-depressant medication use and a marker of low grade systemic inflammation as a potential pathway linking anti-depressant use and CVD in two population based studies. Data were collected in a representative sample of 8131 community dwelling adults (aged 47.4 ± 15.9 years, 46.7% male) from the Scottish Health Surveys (SHS). The use of anti-depressant medication was coded according to the British National Formulary and blood was drawn for the measurement of C-reactive protein (CRP). In a second study, we attempted to replicate our findings using longitudinal data from the Whitehall II study (n = 4584, aged 55.5 ± 5.9 years, mean follow-up 5.5 years). Antidepressants were used in 5.6% of the SHS sample, with selective serotonin reuptake inhibitors (SSRIs) being the most common. There was a higher risk of elevated CRP (>3 mg/L) in users of tricyclic antidepressant (TCA) medication (multivariate adjusted odds ratio (OR) = 1.52, 95% CI, 1.07–2.15), but not in SSRI users (multivariate adjusted OR = 1.07, 95% CI, 0.81–1.42). A longitudinal association between any antidepressant use and subsequent CRP was confirmed in the Whitehall cohort. In summary, the use of anti-depressants was associated with elevated levels of systemic inflammation independently from the symptoms of mental illness and cardiovascular co-morbidity. This might be a potential mechanism through which antidepressant medication increases CVD risk. Further data are required to explore the effects of dosage and duration of antidepressant treatment.

Research highlights
► A series of studies suggest an association between depressive symptoms and higher levels of inflammatory biomarkers, although the role of anti-depressant medication is poorly understood.
► Low grade systemic inflammatory processes may be a key mechanism underlying some of the potential adverse effects of anti-depressant medication, particularly raised CVD risk.
► In a representative sample of 8131 community dwelling adults we found elevated levels of C-reactive protein in users of tricyclic antidepressant medication, independent of psychiatric symptoms.
► A longitudinal association between any antidepressant use and subsequent CRP was confirmed in the Whitehall cohort (n = 4584).