Retrieval from semantic memory using meaningful and meaningless constructs by depressed, stable bipolar and manic patients.

Eleven depressed, 11 stable bipolar and six manic patients, 20 normals and eight late middle-age normals were tested for speech production using a word-fluency task. Fluency was prompted by either a letter (a relatively automatic task), or a semantic category (an effort-demanding task). The results showed that depressed patients were more impaired in speech production than other patients when prompted by a semantic category than when prompted by a letter. A post hoc matched-tasks check suggested that this finding was not due to differences in discriminating power between the two word-fluency tasks. Manic and stable bipolar patients did not differ in their speech production, although matched on age. The results suggest that depressives perform better on more automatic than on effort-demanding tasks, and that manic and stable bipolar patients do not differ in speech production when experimentally imposed restrictions are present.