what is the most common symptom of schizophrenia
Schizophrenia Deficits in cognitive abilities are widely recognized as a core feature of schizophrenia.[38][39][40] The extent of the cognitive deficits an individual experiences is a predictor of how functional an individual will be, the quality of occupational performance, and how successful the individual will be in maintaining treatment.[41] The presence and degree of cognitive dysfunction in individuals with schizophrenia has been reported to be a better indicator of functionality than the presentation of positive or negative symptoms.[38] The deficits impacting the cognitive function are found in a large number of areas: working memory, long-term memory,[42][43] verbal declarative memory,[44] semantic processing,[45] episodic memory,[41] attention, learning (particularly verbal learning).[42] Deficits in verbal memory are the most pronounced in individuals with schizophrenia, and are not accounted for by deficit in attention. Verbal memory impairment has been linked to a decreased ability in individuals with schizophrenia to semantically encode (process information relating to meaning), which is cited as a cause for another known deficit in long-term memory.[42] When given a list of words, healthy individuals remember positive words more frequently (known as the Pollyanna principle); however, individuals with schizophrenia tend to remember all words equally regardless of their connotations, suggesting that the experience of anhedonia impairs the semantic encoding of the words.[42] These deficits have been found in individuals before the onset of the illness to some extent.[38][40][46] First-degree family members of individuals with schizophrenia and other high-risk individuals also show a degree of deficit in cognitive abilities, and specifically in working memory.[46]Â A review of the literature on cognitive deficits in individuals with schizophrenia shows that the deficits may be present in early adolescence, or as early as childhood.[38] The deficits which an individual with schizophrenia presents tend to remain the same over time in most patients, or follow an identifiable course based upon environmental variables.[38][42]