Psychosis Flashcards
Incidence of schizophrenia
Life time incidence: 1%, typical onset 15-45 (18-25 commonly)
Overall risk is even for men and women, but men are affected earlier and more severely
Schizophrenia
A psychotic illness where there is a loss of contact with reality (hallucinations and delusions) and a disordering of thought
Aetiology of schizophrenia
Genetic
Obstetric factors
Substance misuse
Lifestyle factors
Genetic factors in schizophrenia
10x increased for 1st degree relatives, 48% risk if both parents have schiz
MZ twin concordance is 40-50%, DZ twin 10-20%
Rarely single genes may cause (DISC1/2)
Likely multiple risk genes overlapping with other mental illnesses
Obstetric factors in schizophrenia
Maternal malnutrition and illness during pregnancy, particularly 2nd trimester increase risk -> viral infections, pre-eclampsia, low birth weight, emergency C section
Schiz is more likely in people born in winter months
Substance misuse in schiz
LSD, amphetamines, cocaine and cannabis all produce psychotic states
Cannabis increases risk in people with the valine allele of the COMT enzyme
Greatest vulnerability is as a teenager, and it shows a doses response with amount/strength smoked
Socioeconomic factors in schizophrenia risk
Higher prevalence of schiz in lower SES adults which isn’t true for status at birth, indicating downward social drift
Prevalence is also twice as high in urban areas for similar reasons
Migration and ethnicity factors in schizophrenia risk
1st and 2nd generation immigrants show a 3x higher risk of schiz compared to natives.
This varies with populations with black Caribbean and African populations showing the highest rates (4-6x risk compared to white British) –> not understood why
Adverse life experiences in schiz risk
Sexual or physical abuse increases the risk of schizophrenia (Read et al 2005)
Psychological treatment for this may be an important part of the management
Premorbid personality in schizophrenia
1/4 patients with schiz will have had premorbid schizoid personality preceding development of schizophrenia
Schizotypal disorder is also commonly associated, possibly due to a shared genetic basis
Theories of schizophrenia
Neuro-developmental theories
Neuro-transmitter theories
Psychological theories
Neurodevelopmental theories of schizophrenia
Schiz pts have enlarged ventricles and smaller, lighter brains –> but no gliosis indicated it is not degenerative
Premorbid low IQ and learning, memory and executive function.
This may then interact with factors during development to lead to overt schizophrenic symptoms
Neurotransmitter theories of schizophrenia
The dopamine hypothesis argues that mesolimbic DA over-activity is responsible for positive symptoms and negative symptoms are due to mesocortical DA under-activity
All antipsychotics are D2 antagonists, and work best on positive symptoms - DA agonists also produce psychosis
Psychological theories of schizophrenia
These argue that deficits in thinking producing a tendency to jump to conclusions and form overly valued ideas is the source of delusions.
Delusions may also develop out of the desire to rationalise hallucinations –> aberrant salience hypothesis
High expressed emotion
This is a type of familial relationship where relatives are highyl critical or overly involved in the persons life
Kavanagh 1992 showed that this was an important factor in schizophrenic relapse, but did not cause schizophrenia.
Progression of schizophrenia
At risk mental state / prodrome
Acute phase –> characterised by positive symptoms
Chronic phase –> negative symptoms are more obvious
It is now known that this is not a fixed chronological progression and negative symptoms may predate positive
Prodromal state/at risk state
This indicates people at high risk of developing schizophrenia, but it is not inevitable
Low grade negative symptoms –> lack frank psychosis
May deny vague positive symptoms for fear of their significance
Positive symptoms of schizophrenia
Hallucinations
Delusions
Thought disorder
Negative symptoms of schizophrenia
Apathy or avolition Flattened or blunted affect Anhedonia Poverty of movement, thought and speech Social withdrawal
Hallucinations
A percept without a stimulus, as opposed to an illusion which is a mis-interpretation of stimulus.
As all perception is interpretation this distinction is of limited use
Can be of any modality but most commonly auditory 2nd/3rd person –> may be arguing, commentary, to you or thought echo
Delusions
A fixed, usually false over-valued idea or belief which is not culturally explicable
May be delusional perception, passivity phenomena or thought interference
Delusional perception
A real perception is used to reach an entirely delusional conclusion
The sky was red so my wife is cheating on me
Passivity phenomena
Can be of thought, affect, impulse, sensation or movement
‘I’m angry but its not my thoughts’
‘They are making my arms move’
Thought interference
The patient believes that their thoughts are being controlled:
Withdrawal–> ‘people keep plucking the thoughts from my head’
Insertion–> ‘the aliens are putting thoughts in my head’
Broadcast–> ‘people are listening to my thoughts’