Individuals with schizophrenia may experience hallucinations (most reported are hearing voices), delusions (often bizarre or persecutory in nature), and disorganized thinking and speech.
The last may range from loss of train of thought, to sentences only loosely connected in meaning, to speech that is not understandable known as word salad.
Positive symptoms are those that most individuals do not normally experience, but are present in people with schizophrenia.
They can include delusions, disordered thoughts and speech, and tactile, auditory, visual, olfactory and gustatory hallucinations, typically regarded as manifestations of psychosis.
They commonly include flat expressions or little emotion, poverty of speech, inability to experience pleasure, lack of desire to form relationships, and lack of motivation.
Negative symptoms appear to contribute more to poor quality of life, functional ability, and the burden on others than do positive symptoms.
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.
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.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.Efforts to improve learning ability in individuals with schizophrenia using a high- versus low-reward condition and an instruction-absent or instruction-present condition revealed that increasing reward leads to poorer performance while providing instruction leads to improved performance, highlighting that some treatments may exist to increase cognitive performance.Training individuals with schizophrenia to alter their thinking, attention, and language behaviors by verbalizing tasks, engaging in cognitive rehearsal, giving self-instructions, giving coping statements to the self to handle failure, and providing self-reinforcement for success, significantly improves performance on recall tasks.To minimize the developmental disruption associated with schizophrenia, much work has recently been done to identify and treat the prodromal (pre-onset) phase of the illness, which has been detected up to 30 months before the onset of symptoms.