The mean M2 receptor binding in subjects with bipolar disorder was reduced relative to both healthy controls and subjects with major depressive disorder, to an extent that correlated with depressive symptoms. The reduction in the bipolar disorder group could be accounted for either by a reduction in M2 receptor density or affinity or an elevation in endogenous acetylcholine levels. To our knowledge, these data provide the first direct evidence that altered M2 receptor function contributes to mood dysregulation in bipolar disorder.

An experiment was conducted to examine the notion that depressives' responses would reflect a protective self-presentation style (Hill, Weary, & Williams, 1986), the underlying goal of which would be the avoidance of future performance demands and potential losses in self-esteem. In this study, depressed and nondepressed Ss were asked to perform a relatively simple visual-motor task. Half of the depressed and half of the nondepressed Ss were told that if they were successful at the task, they would be asked to perform a 2nd, similar task. The remaining Ss were given no such expectation of future performance. We predicted and found that depressed compared with nondepressed Ss strategically failed at the task when presented with the possibility of future performance and further losses in esteem. Moreover, this strategic failure was associated with some costs; depressed-future performance expectancy Ss experienced more discomfort or negative affect as a result of their performance. The relationship between this depressive self-presentation and self-handicapping strategies is discussed.

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