Hedonic capacity in schizophrenics and their twins.

Audio-taped interviews recorded in the Gottesman-Shields schizophrenic twin series (17 pairs of identical twins, 14 pairs of fraternal same-sex twins, and 12 unpaired twins) were rated for level of hedonic capacity. Schizophrenics who were not hospitalized at the time of their interview were rated significantly lower (more impaired) on hedonic capacity than their normal co-twins. A significant negative correlation was also found between hedonic capacity and severity of illness. Hedonic capacity was found to be genetically influenced, although it appeared to be less heritable than the global diagnosis of schizophrenia. These results are consistent with Meehl's suggestion that reduced hedonic capacity is a heritable personality trait which potentiates the development of schizophrenia among those who are genetically predisposed to the disorder. The results suggest that anhedonia is not a phenotypic vulnerability marker for schizophrenia.