Psychological and physiological changes in severe premenstrual syndrome.

This study investigated differences in nervous system activity and in psychological and behavioural variables between the "baseline" follicular and the premenstrual phases. Twenty women with severe premenstrual syndrome were compared with 20 non-sufferers (10 from each group in each cycle phase). The Patient groups had higher autonomic activity than controls in both phases. In the follicular phase, patients did not differ on other important variables, though most measures were somewhat higher. Premenstrually, patients were higher on several negative moods and lower on cortical arousal. The patients' premenstrual distress appears to arise mainly from chronically high autonomic activity and a decline in cortical arousal, presumably interacting with other neurophysiological fluctuations of the cycle, rather than from any psychological characteristics. The direction of any causal relationship between autonomic and central activity and premenstrual symptoms is unknown.