Abnormal Psychology, the science and treatment of psychological disorders by A. M. Kring, S. L. Johnson, G. C. Davison and J. M. Neale (thirteenth edition) – Chapter 9

Psychosis is a disruption in the experience of reality or disruption of reality testing. Hallucinations are perception-like experiences which occur without an external stimulus and the most common hallucinations are auditory hallucinations. It is not uncommon, as children tend to experience audio-visual hallucinations but this tends to stop at the age of 12 or 13. Delusions are fixed beliefs that are not amenable to change in light of conflicting evidence. They are deemed bizarre if they are implausible, not understandable from same-culture peers and do not derive from ordinary life. There are several types of delusions:

1. Persecutory (most common)
   The idea that a person is being persecuted
2. Referential (most common)
   The idea that there is personal significance in trivial activities of others (e.g., seeing messages)
3. Somatic
   The idea that one’s bodily function or appearance is grossly abnormal
4. Grandiose delusions
   The idea that the person is of exaggerated importance
5. Erotomanic
   The idea that another person (e.g: celebrity) is in love with the person
6. Nihilistic
   The idea that there is impending doom
7. Thought insertion
   The idea that thoughts are being inserted
8. Thought broadcasting
   The idea that thoughts are being broadcast

Schizophrenia includes positive, negative and disorganized symptoms. Positive symptoms consist of symptoms that make it difficult for a person to tell what is real and what is not. Negative symptoms consist of behavioural deficits in motivation, pleasure, social closeness and emotion expression. Disorganized symptoms refer to the lack of ability to organize behaviour and conform to community standards. Catatonic behaviour is extremely disorganized behaviour. There are several negative symptoms:

1. Avolition (apathy) (most common)
   Reduced self-motivated goal-oriented behaviour
2. A-sociality
   Reduced interest in social activities
3. Anhedonia
   Reduced experience of pleasure
4. Alogia
   Reduced speech production
5. Blunted affect (most common)
   Lack of outward expression of emotion without regards to the inner experience of emotion

Other symptoms include jumping to conclusions (1), disrupted self-experience (2), neurocognitive difficulties (3) and anosognosia (4): reduced insight into the illness. The severity of symptoms can be assessed using the Positive and Negative Syndrome Scale (PANSS) and using the beads task. Neurocognitive deficits can be measured by measuring working memory.

There is a strong genetic component in schizophrenia. There are several risk factors for developing a psychosis: being a migrant (1), urbanization (2), social exclusion (3) and trauma (4). A psychosis can be traumatic. A sense of social exclusion can play an important role in developing psychosis.

The social defeat hypothesis states that social exclusion increases the risk of psychosis. The dopamine hypothesis states that schizophrenia is related to excess activity of dopamine. The dopamine neurons in the prefrontal cortex may be underactive, which leads to overactivity of dopamine in the rest of the brain.

The cognitive model of auditory hallucinations states that an intrusive thought occurs, which is misattributed to an external source. This leads to the appraisal of the hallucination which produces different behaviour, resulting in new intrusive thoughts.

The staging model states that schizophrenia occurs in stages and that every stage is more severe and lasts longer. The goal of treatment is avoiding the next stage

1. Stage 0: Increased risk
   A decrease in cognitive functioning, reduced psychomotor abilities and developmental milestones occur later. There are no symptoms.
2. Stage 1: Prodromal phases / at-risk mental state (ARMS)
   There are subclinical positive symptoms, negative symptoms, functional deterioration, mood swings and an indication of cognitive problems.
3. Stage 2: First episode: positive symptoms and worsening of cognitive problems
   First psychotic episode, positive symptoms and worsening of cognitive problems.
4. Stage 3: Multiple episodes with stable phases or remission
   There are three possible outcomes of this stage: incomplete remission of the first episode (1), new episodes with reduced recovery (2) or more relapse with further reduction functioning (3).
5. Stage 4: Chronic phase
   Poor response to treatment. There are no indications of progressive neurodegeneration until ±65 years.