Social withdrawal, sloppiness of dress and hygiene, and loss of motivation and judgment are all common in schizophrenia.
Distortions of self-experience such as feeling as if one's thoughts or feelings are not really one's own to believing thoughts are being inserted into one's mind, sometimes termed passivity phenomena, are also common.
People 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.
The validity of the positive and negative construct has been challenged by factor analysis studies observing a three dimension grouping of symptoms.
Different terminology is used, but a dimension for hallucinations, a dimension for disorganization, and a dimension for negative symptoms are usually described.Efforts to improve learning ability in people 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 people 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.Both maternal stress and infection have been demonstrated to alter fetal neurodevelopment through pro-inflammatory proteins such as IL-8 and TNF.It has been hypothesized that in some people, development of schizophrenia is related to intestinal tract dysfunction such as seen with non-celiac gluten sensitivity or abnormalities in the intestinal flora.The question of how schizophrenia could be primarily genetically influenced, given that people with schizophrenia have lower fertility rates, is a paradox.It is expected that genetic variants that increase the risk of schizophrenia would be selected against due to their negative effects on reproductive fitness.The extent of the cognitive deficits someone experiences is a predictor of how functional they will be, the quality of occupational performance, and how successful they will be in maintaining treatment.Deficits in verbal memory are the most pronounced in someone with schizophrenia, and are not accounted for by deficit in attention.Both working memory tasks and gamma oscillations are impaired in schizophrenia, which may reflect abnormal interneuron functionality.Deficits in executive functions, such as planning, inhibition, and working memory, are pervasive in schizophrenia.