Effects of expression and inhibition of negative emotions on health, mood states, and salivary secretory immunoglobulin A in Japanese mildly depressed undergraduates

Previous studies have indicated that expression of negative emotions facilitates mental and physical health and inhibition of negative emotions increases susceptibility to illness. This study was conducted to examine whether those findings can be expanded to populations with non-Western cultural backgrounds. Specifically, we explored effects of expression and inhibition of negative emotions on health, mood states, and mucosal immune function in mildly depressed Japanese individuals. 16 depressed and 16 nondepressed female undergraduates were required either to write about their unpleasant experiences and superficial topics or to suppress any emotional responses and thoughts about them. Secretory immunoglobulin A (s-IgA) in saliva and psychological indices were measured at an experimental session and at a follow-up 1 wk. later. Beneficial effects of expression of emotions on subjective health were indicated in the nondepressed group, whereas harmful effects of inhibition on subjective health were shown in the depressed group. Emotional expression by writing improved mood states both in the depressed and nondepressed groups but induced elevation of salivary s-IgA only in the depressed group.