6.1.2 Flashcards
Family and Twin Studies (Schizophrenia)
Suggest a genetic predisposition to schizophrenia can be inherited. MZ twins have a 42% concordance rate, DZ twins 9% (Gottesman and Shields, 1966).
Genome-wide Association Studies (GWAS)
Certain alleles, such as those linked to dopamine and GABA, are more common in individuals with schizophrenia.
Gene Deletion and Schizophrenia Risk
Deletion of certain genes (e.g., COMT) increases the risk of developing schizophrenia.
Dopamine Hypothesis
Schizophrenia may be caused by excess dopamine. However, dopamine antagonists don’t reduce negative symptoms in all cases.
Mesocortical Pathways and Schizophrenia
A lack of dopamine in mesocortical pathways may lead to negative and cognitive symptoms of schizophrenia.
Mesolimbic Pathways and Schizophrenia
Excess dopamine in mesolimbic pathways, possibly due to upregulation, may contribute to symptoms like delusions.
Self-Monitoring Error (Schizophrenia)
People with schizophrenia may mistake their own sub-vocal thoughts for external voices, causing auditory hallucinations.
Difficulties with Mentalising (Schizophrenia)
People with schizophrenia may struggle to understand others’ intentions or mental states, leading to paranoia and social withdrawal.
Counter-Evidence Bias (Schizophrenia)
Individuals with schizophrenia may make inferences without sufficient evidence, leading to delusions and failure to update beliefs.
Biological Evidence – Amphetamines
Rats injected with drugs increasing dopamine (e.g., amphetamines) displayed schizophrenic-like symptoms, such as strange movements and social withdrawal.
Biological Evidence – Apomorphine
Apomorphine, a dopamine agonist, does not increase symptoms in individuals with schizophrenia or trigger symptoms in healthy controls.
Cognitive Evidence – Self-Voice Recognition
People with schizophrenia are less likely to recognize recordings of their own voices compared to healthy controls.
Cognitive Validity Issue
It is difficult to determine if cognitive differences are a cause or an effect of schizophrenia.
Individual and Situational Explanations
Schizophrenia symptoms vary between individuals, with differences in hallucinations and social withdrawal. These may be explained by individual thinking errors.
Nature versus Nurture in Schizophrenia
Twin studies support nature (genetics), but environmental factors (nurture) also play a role, such as drug use and stress.
Schizophrenia and Cognitive Differences
Cognitive explanations do not address why some people have faulty thinking, such as due to biochemical differences (nature) or family modeling (nurture).
Interaction of Nature and Nurture in Schizophrenia
Schizophrenia likely results from both genetic (nature) and environmental (nurture) factors, with environmental factors influencing gene expression.
Diathesis-Stress Model of Schizophrenia
This model suggests that genetic predisposition (nature) interacts with environmental stressors (nurture) to trigger schizophrenia symptoms.
Environmental Stressors and Schizophrenia
Stressors like traumatic life events, discrimination, or poverty may trigger schizophrenia symptoms in genetically predisposed individuals.
Shared Environment Fallacy (Schizophrenia)
Twin studies may suffer from the shared environment fallacy, where both twins are exposed to similar environmental factors, complicating the conclusions about genetics.
