A comparison of delusions and overvalued ideas.

The relationship between delusions and overvalued ideas is uncertain, and has clinical as well as conceptual implications. This study aims to compare delusions and overvalued ideas on several characteristics that might further describe and distinguish them. A total of 24 individuals with delusions and 27 with overvalued ideas were recruited from a psychiatric service and assessed using a semistructured interview. Deluded individuals were less likely to identify what might modify their belief, less preoccupied, and less concerned about others' reactions than those with overvalued ideas. Delusions were less plausible and their onset less likely to appear reasonable. Delusions were more likely to have abrupt onset and overvalued ideas a gradual onset. Conviction and insight were similar in the 2 groups. Belief conviction and insight may be an inadequate basis for separating delusions from overvalued ideas. Abrupt onset, implausible content, and relative indifference to the opinions of others may be better distinguishing features.