1001 - Biology of Schizophrenia Flashcards
What is Schizophrenia?
Neurodevelopmental disorder of impaired neuronal connectivity, with brain abnormalities in grey and white matter.
What are the clinical features of schizophrenia?
Positive - Hallucinations, delusions, and thought disorder
Negative - decreased motivation, altered expressions of emotions, decreased speech, anhedonia
Cognitive deficits - Impairments in executive functioning, attention, verbal learning, verbal fluency, and working memory.
What are the diagnostic criteria of schizophrenia
Characteristic symptoms - 2 or more present for 1 month (delusions, hallucinations, disorganised speech (thought disorder), disorganised/catatonic behaviour, negative symptoms.
Reduced functioning - occupational/social/self care
Duration - Continuous signs for at least 6 months.
What is the epidemiology of schizophrenia?
Point prevalence - 4.6/1000
Lifetime prevalence - 4.0/1000
F=M
In poorer countries - lower prevalence with female excess.
What is the genetics of schizophrenia?
There is a genetic loading, particularly among identical twins. 45% in monozygotic twins, which demonstrates that there are some environmental factors. Not mendelian - polygenic interactions (100s of genes). There are a number of copy number variants (CNV) common to schizophrenia and other mental illnesses, believed to be associated with abnormal neurodevelopment.
How do environmental factors interplay with schizophrenia?
Obstetric complications, maternal infections (particularly influenza) and malnutrition are important for early development. As are immigrant status and chronic cannabis abuse later in life.
What neurotransmitter systems are involved in schizophrenia?
Abnormal dopaminergic neurotransmission
Possible roles for glutamate, GABA, and serotonin.
What are the strengths and weaknesses of the dopamine hypothesis of Sz?
Illicit drugs with increase DA release may induce psychosis
Medications that block DA receptors DO reduce Sz symptoms
Cannabis (causing DA release) can cause or exacerbate Sz.
BUT
These drugs don’t act only on dopaminergic neurons
Antipsychotics targeting DA don’t have immediate effect
Antipsychotics have little effect on negative symptoms
What is the brain pathology of schizophrenia?
Reduced grey matter in the right frontal and temporal Cx and insula
Thinning of corpus callosum and intra-hemispheric fibre tracts.
Gyrification index (essentially surface area to dura size/measure of folding) shows reduced cortical folding.
What neuropathological findings can be found in schizophrenia?
Reduced brain weight (grey and white) with enlarged lateral and third ventricles.
Decreased markers of synapses and dendrites.
Absence of neurodegenerative changes and gliosis (suggesting prenatal brain insult)
Cytoarchitecture abnormalities.
Thinning of corpus callosum
What are event-related potentials?
Measured electrical brain activity when a person performs a task or is exposed to a stimulus.
How do event-related potentials interplay with schizophrenia?
Allows a measurement of the brain malfunction in Sz, appearing before symptoms, and sometimes independent of symptoms in first degree relatives (so independent of the clinical state of the patient).
