A correlational study of cardiovascular autonomic functioning and unipolar depression

Cardiovascular autonomic functioning was assessed in 22 drug-free inpatients diagnosed by DSM-III criteria as having a unipolar depression. Sympathetic cholinergic, alpha- and beta-adrenergic activity were assessed via the measurement of forearm blood flow (FBF), digital blood flow (DBF), and the cardiac pre-ejection period (PEP), respectively. These parameters were correlated with total Hamilton score (HT) (using partial correlations to control for extraneous autonomic variables) to identify the specific autonomic correlates of unipolar depression. Significant negative correlations were found between HT and supine FBF and significant positive correlations between HT and PEP. Large effect-size, negative correlations (which approached significance) were found between HT and DBF. It is concluded that there is a specific autonomic profile of unipolar depression, characterized by a decrease in central sympathetic cholinergic outflow, coupled with increases in alpha-adrenergic and decreases in beta-adrenergic activity. Further, this profile is not merely a static hallmark of depression but covaries with the severity of the depression, independent of other autonomic activity.