Schizophrenia - Understanding & Causes PDF

Schizophrenia(s) Understanding schizophrenia Understanding schizophrenia(s): Does acute vs. chronic matter? — Carpenter (2012): ◦ Is psychotic experience (sometimes) a meaningful response to the conditions of one’s life? a “spiritual emergency” requiring “new self-construction...

Schizophrenia(s) Understanding schizophrenia Understanding schizophrenia(s): Does acute vs. chronic matter? — Carpenter (2012): ◦ Is psychotic experience (sometimes) a meaningful response to the conditions of one’s life? a “spiritual emergency” requiring “new self-construction”? ◦ Acute psychotic break vs. Chronic psychosis ◦ Evidence that brain-altering anti-psychotic medications have short-term positive effects, but do they have long- term negative effects? ◦ “A brain that never truly had a ‘chemical imbalance’ now has one for sure, caused by drug withdrawal.” — Eleanor Longden: The Voices in My Head (14 min) https://www.youtube.com/watch?v=syjEN3peCJw Clues to Biological Causes of Schizophrenia Q: When does schizophrenia start?  Schiz. Causal Factors: 1. Genetics ◦ Offspring of two parents w schizophrenia = 46% ◦ Epigenetics: env’tal conditions affect gene expression  Schizophrenia Causal Factors: 2. Abnormal Brain Structures ◦ Enlarged brain ventricles (perhaps particularly associated with negative symptoms) ◦ Abnormalities in prefrontal cortex (smaller, low activity) ◦ Variety of other areas: hippocampus, limbic system, basal ganglia, reductions in white matter (connections, memory)… Schizophrenia Causal Factors: 3. Neurotransmitters ◦ Dopamine (details on next slide) ◦ Perhaps other neurotransmitters as well? Evidence regarding neurotransmitters — Dopamine (DA) ◦ Phenothiazines (the first anti-psychotics) reduce functional level of DA (they bind to D-2 receptors, preventing DA from binding there, thus reducing the activity level of DA). ◦ Compare with use of L-dopa with Parkinson’s Disease ◦ Amphetamines increase DA function & also increase psychotic symptoms ◦ Brain images show more DA receptors & sometimes more DA in some brain areas of people with schizophrenia. ◦ Regarding dopamine, now we suspect: – May be excess DA activity in mesolimbic pathway (cognition & emotion), and this is associated with positive symptoms – May be low DA activity in prefrontal area (attention, motivation), and this is associated with negative symptoms. — Other possible neurotransmitters: serotonin, glutamate, GABA…  Schizophrenia Causal Factors 4. Birth complications: ◦ e.g., 30% of people with schizophrenia experienced perinatal hypoxia. ◦ Prenatal virus exposure: flu virus in 2nd trimester. 5. Mid-March /winter peak in births of people with schizophrenia…  Reduced Sunlight Exposure as a Prenatal Causal Factor ? ◦ Mid-March peak in births of people with schiz. ◦ In Brazil, rainfall is an even better predictor of schizophrenia births than is flu season ◦ Bigger spring birth effect in Northern hemisphere, and gets bigger the further north you go (where people live further from equator and get less sunlight in winter) ◦ In Australia, get peak in Spring schizophrenia births in years with El Niño weather system that casts a gloom over Australia ◦ If pregnant rats are deprived of UV light or Vitamin D, their offsprings’ brains have less nerve growth factor and enlarged ventricles! Perhaps prenatal lack of UV light & low levels of Vitamin D increase risk for schizophrenia.  Q: When does schizophrenia begin? Is it a developmental neurocognitive disorder? (see Michael F. Green’s book, Schizophrenia Revealed: From Neurons to Social Interactions) Schizophrenia may not centrally be about psychotic symptoms, but instead about 3 key aspects: ◦ 1) disrupted neural connections, specifically reduced neural connectivity, which leads to: ◦ 2) neurocognitive deficits, which lead to mis- interpretations and confusions, & eventually to: ◦ 3) functional impairment (e.g., in work, in relationships) Evidence of problems with neurodevelopment in early childhood — Home movies: see negative emotions, awkward movements — Minor physical anomalies (MPA’s) of head, feet, hands, face — Abnormal fingerprints (even when compared to MZ twin!) — Increased incidence of ambiguous handedness  What normally happens in neurodevelopment in 2nd trimester? Answer: Migration of neurons from inner brain layers to outer brain areas. Q: What happens to neurons during the 2nd trimester in schizophrenia? — They stop short of their correct final destination. — They end up out of alignment. — They fail to make the correct connections. — They get excessively pruned. (Excessive pruning of dendrites can cause neurons to squeeze together, to be densely packed.) Some interesting points to consider — Why do overt symptoms begin so much later than the neural problems? — Schizophrenia appears to be both: ◦ a neurodevelopmental disorder (neural disruptions begin prenatally) and ◦ a progressive disorder: e.g., brain shrinkage occurs after onset of symptoms, & there is a loss of previous social functioning.  Neurocognitive deficits are found in schizophrenia (90% show deficits in at least one neurocognitive domain) — Perception: backward masking — Vigilance/ Sustained attention: e.g., Continuous Performance Test — Sensory gating — Memory — Problem solving/ Executive functions — Social cognition: recognition of emotions, theory of mind, understanding social rules Q: Is schizophrenia always associated with neurocognitive deficits? Not always, and not uniformly. In an outpatient study: –90% had at least one; –75% had at least two.  Causal factors in schizophrenia: Any psychosocial factors involved? — Behavioral: fail to attend to social cues; don’t get reinforced for doing so. — Cognitive: cognitive problems + overwhelming information & strange perceptual experiences; also neg automatic thoughts, reasoning biases — NOT Family: “schizophrenogenic mother”: overprotective + rejecting (No research support) — NOT Double-bind communication: mismatch between content and feeling/ tone/ non-verbals — “Expressed emotion” (EE): family is overinvolved + critical. Is associated with increased relapse.