19.02.1 Psychosis and Schizophrenia

Psychosis is a phenomenon that is associated with a number of disorders, including bipolar affective disorder (manic depression), drug withdrawal, and most evidently, schizophrenia. The drugs used to treat schizophrenia are also used to treat other disease entities manifesting in psychosis, which is why they are referred to as antipsychotics rather than antischizophrenics.

Schizophrenia itself is in fact a syndrome, characterised by a number of symptoms which different sufferers demonstrate to different extents.  The symptoms have been grouped into three major dimensions; positive symptoms reflecting an excess or distortion of normal thinking, negative symptoms reflecting a loss or reduction in normal behaviours, and cognitive symptoms reflecting a deficit in some cognitive behaviours such as attention and working memory. Positive symptoms are akin to the usual “psychosis”, and may manifest as delusions, hallucinations, and disorganised thought and speech. Negative symptoms may show as blunted emotional responses, diminution in goal directed behaviours, and lack of interest in or inability to experience pleasure. Schizophrenia is characterized as a thought disorder, although depression may occur. The symptoms of schizophrenia can be extremely distressing, and cause major disruption to social and occupational functioning. The average age of onset is adolescence or early adulthood, and course is often chronic, rarely remitting, and usually improved through pharmacological intervention.

The cause of schizophrenia remains unknown, but current evidence suggests it involves a gene-environment interaction. The collective effect of numerous common genetic variants interacts with environmental factors, which are moderated by the genes, causing alterations to brain development and, in time, information processing. Environmental factors that have been identified include pre-, peri-, and post-natal effects (stress, malnutrition, infection, obstetric complication), early-life stress (trauma, separation), frequent drug use (cannabis, amphetamines), and stressful life events (migration, illness, adversity etc.).