Lecture 36: Psychosis/Schizophrenia Flashcards
(31 cards)
what is psychosis?
Syndrome (mixture of symptoms) that may occur in many different disorders
- delusions, hallucinations, distorted reality testing, abnormal speech and behaviour, motor disturbances
- paranoid, excited/disorganised or depressive
- defining feature of schizophrenia, schizoaffective disorder, drug-induced psychotic disorder, etc
- may occur in mania, depression, dementias (alzheimers and parkinsons), medical illness or be drug induced
what are the symptoms of psychosis?
Positive symptoms
- reflect an excess or distortion of normal funtions
- perception - hallucinations
- reality testing - delusions
- disorganised speech or behaviour
Negative symptoms
- reflect a diminution or loss of functions
- e.g. emotion, thought, speech and behaviour
what are some positive symptoms of psychosis?
reflect an excess or distortion of normal functions
- delusions - fixed false beliefs
- ideas (delusions) of self-reference
- hallucinations - perceptions in the absence of external stimuli
- loss of thought boundaries
- passivity
- disorganised behavious and movements
- formal thought disorder
what is thought disorder?
- difficuly organising thoughts or making logical connections
- experience of one’s mind racing from one unrelated thought to another
- thought blocking: a feeling that thoughts are removed from one’s head
what are the negative symptoms of psychosis?
reflect a diminuition or loss of functions
- affective blunting
- poverty of thought/speech
- lack of volition/apathy (power/interest)
- anhedonia (lack of interest in activities used to find enjoyable)
- impaired attention
what is schizophrenia?
- 2 or more of the following symptoms at least one month of active symptoms with an overall duration of 6+ months
- delusions
- hallucinations
- disorganised speech
- disorganised or catatonic behaviour
- negative symptoms
what are the symptoms in schizophrenia?
positive symptoms
Hallucinations
- auditory 19-51%
- somatic/tactile 20-30%
- olfactory 1-5%
- visual 15%
Delusions
- persecutory up to 47%
- of being controlled up to 25%
- of reference up to 21%
- of mind reading up to 19%
Formal thought disorder ~30%
Negative symptoms
- affective blunting (lack of emotion) 32-54%
- alogia (possess or produce speech) 20-30%
- avolition (lack of motivation) 33-41%
- anhedonia (loss of enjoyment) 38-41%
- attention 25-30%
What is the dementia praecox?
- Kraepelin divided ‘insanity’ into dementia praecox and manic depression
- emphasised chronicity and delusions and hallucinations in dementia praecox
- onset typically in young adulthood, rare in children
what is the epidemiology of schizophrenia?
- lifetime prevalence approx 1%
- incidence is about 15 new cases per 100,000 population per annum
- M:F incidence, males twice as affected as females
- 5-fold variation in incidence internationally. there are higher rates with increased immigration and urban living
- core symptoms are the same in all groups
what is the 2015 NZ epidemiology?
- analysis of stats NZ datasets in 2017
- prevalence 6.7/1000 people aged 18-64
- Males: 8.9/1000, Females: 4.7/1000 (OR=0.52)
Ethnicity:
- european: 16.7/1000 (OR=3.36)
- pasifika: 10.9/1000 (OR=1.70)
- asian: 3.0/1000
- highest prevalence in 25-54 age groups
when/how does schizophrenia start?
- age of onset is early 20s for males and late 20s for females
- doesn’t instantly happen, may be preceded by a prodrome (gradual deterioration over 3-24 months)
Symptoms of prodrome:
- mild/moderate disturbances in perception, cognition, language, motor function, will, initiative, level of energy and stress tolerance
what are the demographics/risk factors
- more common in unmarried
- more common in low SES (downward drift)
- more common in immigrants, immigrants children have risk halfway between immigrants and locals
does schizophrenia run through the family?
identical twins have 48% chance of developing schizophrenia
increasing genetic variation as you go down the bloodline, the risk is less
what are the risk factors for schizophrenia?
genetic vulnerability, prenatal environment, childhood environment and later life environment increase the risk of onset of schizophrenia
- dose response between psychosis and life time cannabis use, abuse and dependence
what is the hypothetical gene-environment interaction threshold model?
schizophrenia is caused by a combination of genetic and environmental factors
what has been found about the genes of schizophrenia?
no schizophrenia gene has been identified
Study: Rare structural variants disrupt multiple genes in neurodevelopmental pathways in schizophrenia science 2008, 320:539; updated: neuron 2015, 86:1203
Copy Number Variant approach used to study schizophrenia genetics
- genome wide analysis of individuals, rare, structural mutations (CNVs) in schizophrenia vs controls
- genomic microdeletions and microduplications
- rates of these were higher in patients vs controls
3x higher in schizophrenia cases overall
4x in cases with onset by age 18
Gene disrupted by mutations were not random
- generally involved pathways controlling neuronal signalling and brain development
how would a genetic component of schizophrenia be affected overtime?
Genetic negatives:
- lower fertility rates vs general population
- mortality rates 2x general populations
- suicide significant
Genetic positives:
- negative byproduct of an otherwise positive evolutionart process (e.g. related to creativity/language/cortical development)
- lower rates of rheumatoid arthritis
how might genetic changes affect brain function?
schizophrenia is associated with reduced cortical connectivity
figure B - Rich Club Circuit
- bulateral precuneus, superior frontol cortex, superior parietal cortex, and the insula in both health and patient populations
Figure C - Edges across individual brain networks (both controls and patients) were divided into 3 distinct classes
- rich club: rich club members (red)
- feeder connections (rich club: non-rich club; orange)
- local connections (yellow)
Figure A- patients had a significantly reduced intensive connectivity (at central hubs) compared with controls
what are the structural changes in the brain?
loss of brain volume
how does abnormal connectivity affect schizophrenia?
abnormal connectivity is a basis for schizophrenia
relevant genetic abnormality
- signalling/neuronal integrity
age of onset
- coincides with massive synaptic pruning in adolescence/early adulthood
symptomatic heterogeneity
- reflecting changes in many different functional circuits
what is the clincal course of schizophrenia?
- Prodrome: 73% of patients
- full recovery 14% (mild symptoms, good social functioning for more than 2 years)
- improved/good outcomes in 40-42%
- poor outcome 20-30%
- rates of relapse will be influenced by medication compliance, substance use, availability of services, social challenges etc
what are the predictors of a good outcome?
- acute onset
- stressful life event at time of onset
- a family history of depressive illness
- no family history of schizophrenia
- confusion or perplexity
- prominent affective symptoms
- married
- higher IQ
what are the predictors of poorer outcome?
- younger age at onset
- insidious onset
- unmarried
- emotional blunting
- lower IQ
- poor work record
- prominent schizoid traits premorbidly
- male
what are the social and health impacts of schizophrenia?
- high unemployment
- poverty
- small/no social network/isolation
- poor nutrition
- high smoking rates
- high rates of obesity
- high rates of rehospitalisation
- reduced life expectancy (>15y)
- high rates of drug abuse
- higher rates of suicide (~10%)
