Cognitive deficits become worse at first episode psychosis but then return to baseline, and remain fairly stable over the course of the illness.The deficits in cognition are seen to drive the negative psychosocial outcome in schizophrenia, and are claimed to equate to a possible reduction in IQ from the norm of 100 to 70–85. Cognitive deficits may be of neurocognition (nonsocial) or of social cognition. Neurocognition is the ability to receive and remember information, and includes verbal fluency, memory, reasoning, problem solving, speed of processing, and auditory and visual perception. Verbal memory and attention are seen to be the most affected. Verbal memory impairment is associated with a decreased level of semantic processing (relating meaning to words). Another memory impairment is that of episodic memory. An impairment in visual perception that is consistently found in schizophrenia is that of visual backward masking. Visual processing impairments include an inability to perceive complex visual illusions. Social cognition is concerned with the mental operations needed to interpret, and understand the self and others in the social world. This is also an associated impairment, and facial emotion perception is often found to be difficult. Facial perception is critical for ordinary social interaction. Cognitive impairments do not usually respond to antipsychotics, and there are a number of interventions that are used to try to improve them; cognitive remediation therapy is of particular help.Neurological soft signs of clumsiness and loss of fine motor movement are often found in schizophrenia, which may resolve with effective treatment of FEP.
Psychosis is noted in Other specified schizophrenia spectrum and other psychotic disorders as a DSM-5 category. Schizoaffective disorder is diagnosed if symptoms of mood disorder are substantially present alongside psychotic symptoms. Psychosis that results from a general medical condition or substance is termed secondary psychosis.Psychotic symptoms may be present in several other conditions, including bipolar disorder, borderline personality disorder, substance intoxication, substance-induced psychosis, and a number of drug withdrawal syndromes. Non-bizarre delusions are also present in delusional disorder, and social withdrawal in social anxiety disorder, avoidant personality disorder and schizotypal personality disorder. Schizotypal personality disorder has symptoms that are similar but less severe than those of schizophrenia. Schizophrenia occurs along with obsessive–compulsive disorder (OCD) considerably more often than could be explained by chance, although it can be difficult to distinguish obsessions that occur in OCD from the delusions of schizophrenia. There can be considerable overlap with the symptoms of post-traumatic stress disorder.A more general medical and neurological examination may be needed to rule out medical illnesses which may rarely produce psychotic schizophrenia-like symptoms, such as metabolic disturbance, systemic infection, syphilis, HIV-associated neurocognitive disorder, epilepsy, limbic encephalitis, and brain lesions. Stroke, multiple sclerosis, hyperthyroidism, hypothyroidism, and dementias such as Alzheimers disease, Huntingtons disease, frontotemporal dementia, and the Lewy body dementias may also be associated with schizophrenia-like psychotic symptoms. It may be necessary to rule out a delirium, which can be distinguished by visual hallucinations, acute onset and fluctuating level of consciousness, and indicates an underlying medical illness.