Change in the relationship between anhedonia and functional deficits over a 20-year period in individuals with schizophrenia.

Although early theorists suggested that deficits in emotional experience be considered a hallmark characteristic of schizophrenia, there has been limited research, and inconsistent findings, on the relationship between anhedonia and functional capacity in individuals after the onset of schizophrenia. Stronger relationships have typically been reported for chronic samples in contrast to first episode samples, although it is not clear whether this is due to selection biases that influence recruitment in these different groups, or whether results reflect a change over the course of illness. The current longitudinal study examined the relationship between physical anhedonia and functional status in a sample of 61 individuals with schizophrenia at regular intervals over a 20-year period. Subjects were recruited into the study during an index hospitalization and completed assessments at 2-, 4.5-, 7.5-, 10-, 15-, and 20-year follow-ups. Analyses indicate that the relationship between anhedonia and impairments increases over time, although mean performance on these measures is stable across this same time period. These results suggest increasing convergence of impairments in emotional, adaptive, and cognitive capacities over time, with physical anhedonia associated with poorer outcome.