Epidemiology prevalence: 0.5%-1%; M:F = 1:1 mean age of onset: females ~27; males ~21 Etiology multifactorial: disor...
Epidemiology
- prevalence: 0.5%-1%; M:F = 1:1
- mean age of onset: females ~27; males ~21
Etiology
- multifactorial: disorder is a result of interaction between both biological and environmental factors
- genetic - 50% concordance in monozygotic (MZ) twins; 40% if both parents have schizophrenia; 10% of dizygotic (DZ) twins, siblings, children affected
- neurochemistry – “dopamine hypothesis” theory: excess activity in the mesolimbic dopamine pathway may mediate the positive symptoms of psychosis (i.e. delusions, hallucinations, disorganized speech and behaviour, and agitation)
- neuroanatomy - decreased frontal lobe function, asymmetric temporal/limbic function, decreased basal ganglia function; subtle changes in thalamus, cortex, corpus callosum, and ventricles; cytoarchitectural abnormalities
- neuroendocrinology - abnormal growth hormone, prolactin, cortisol, and adrenocorticotropic hormone
- neuropsychology - global defects seen in attention, language, and memory suggest lack of connectivity of neural networks
- indirect evidence of geographical variance, winter season of birth, and prenatal viral exposure
Pathophysiology
- neurodegenerative theory
- natural history may be rapid or gradual decline in function and ability to communicate
- glutamate system may mediate progressive degeneration by excitotoxic mechanism which leads to production of free radicals
- neurodevelopmental theory - abnormal development of the brain from prenatal life
- neurons fail to migrate correctly, make inappropriate connections, and break down in later life
- inappropriate apoptosis during neurodevelopment resulting in faulty connections between neurons
Clinical Pearl
Supportive Evidence for Dopamine Hypothesis
Dopamine (DA) agonists exacerbate schizophrenia
Antipsychotic drugs act by blocking post-synaptic DA receptors
Potency of many antipsychotic drugs correlates with D2 blockade of post-synaptic receptors
Antipsychotic drugs are associated with an increase in the number of D2 and D4 post-synaptic receptors
Related Links :
Schizophrenia (continued 1)
Schizophrenia (continued 3)
Schizophrenia (continued 4)
