Motivation and Hedonic Capacity in Mood Disorders and Schizophrenia
Motivation is an important concept in terms of everyday functioning. Many everyday acts are likely performed because of their intrinsically reinforcing consequences. Depression is known to reduce hedonic capacity and may reduce the motivation to perform otherwise reinforcing activities because of interference with either the pleasure experienced from them (consummatory anhedonia) or the anticipated pleasure that motivates a person to perform them (anticipatory anhedonia). Recent research on anhedonia has suggested that these different types of anhedonia may be operative in schizophrenia and major depression, with reduced ability to experience pleasure (consummatory anhedonia) the modal phenomena in major depression, with preserved ability to experience pleasure seen in people with schizophrenia.17 In people with schizophrenia, anticipatory anhedonia apparently predominates in the absence of notable consummatory anhedonia. Interestingly, the little research done on depression and anhedonia in people with schizophrenia suggests an increased frequency of consummatory anhedonia in individuals with schizophrenia who have depressed mood symptoms.18 Thus, depression's impact on everyday functioning in schizophrenia and mood disorders may be motivational in nature, through impacts on hedonic capacity. Depressed people with schizophrenia may have qualitatively similar hedonic deficits compared to people with major depression.18 Individuals with persistent cognitive deficits, such as those seen in schizophrenia, may also be unable to volitionally retrieve their memories of previous positive experiences, leading to an increase in the inability to anticipate the pleasurable consequences of every-day actions.