While speaking in public, changing topics frequently is a positive symptom of schizophrenia. It is an example of disorganised thinking and speech, specifically known as loosening of associations or derailment, where the normal structure of thinking becomes muddled and illogical. Positive symptoms are 'pathological excesses' or 'bizarre additions' to a person's behaviour.

The other symptoms of schizophrenia are grouped into three categories: positive symptoms, negative symptoms, and psychomotor symptoms.

Positive symptoms include delusions, where patients may feel threatened or believe they are specially empowered (delusions of grandeur) or controlled by others. They also include hallucinations (perceptions without external stimuli) like auditory, visual, and somatic hallucinations. Additionally, patients may show inappropriate affect, experiencing emotions unsuited to the situation. Other formal thought disorders include neologisms (inventing new words) and perseveration (inappropriate repetition of thoughts).

Negative symptoms are 'pathological deficits' and include alogia or poverty of speech, which is a reduction in speech and speech content. Patients may also show blunted affect (less anger, sadness, joy) or flat affect (no emotions at all). Other deficits include avolition (apathy and inability to start or complete actions) and social withdrawal, where patients become totally focused on their own ideas and fantasies.