Lecture 5 - theories Flashcards
Social Defeat Hypothesis
This theory suggests that social defeat, or the experience of being excluded, marginalized, or rejected, can lead to an increased risk of psychosis.
The theory posits that chronic exposure to social defeat elevates dopamine activity in the brain, particularly in the striatum, which is linked to the development of psychotic symptoms.
Immigrants or refugees who experience social exclusion in a new country may develop heightened dopamine activity due to ongoing stress, increasing their risk of developing schizophrenia or other psychotic disorders.
The social causation hypothesis
Adverse social-economic conditions increase risk on poor mental health –psychosis included. Chronic stress from poverty, unemployment, or poor living conditions can contribute to the onset of mental illness.
A person living in poverty may experience ongoing stress, lack of access to healthcare, and social marginalization, all of which contribute to the development of psychosis or exacerbate existing mental health conditions.
Social Selection/Drift Hypothesis
This theory suggests that individuals with poor mental health (including psychosis) drift into adverse socioeconomic conditions as their condition impairs their ability to maintain stable employment or social connections. It contrasts with the social causation hypothesis, which argues that adverse socioeconomic conditions lead to poor mental health.
A person diagnosed with schizophrenia may struggle to hold a job and gradually drift into poverty, further exacerbating their mental health issues.
Neurodevelopmental Hypothesis of Psychosis
This hypothesis suggests that abnormalities in brain development, including disturbed cognitive, social, and motor functions during early life, increase the likelihood of psychosis. These developmental issues often manifest in pre-psychotic or prodromal stages and eventually lead to full-blown psychotic disorders.
A person who shows early signs of cognitive and social difficulties during adolescence might later develop schizophrenia, with these early issues acting as precursors to the disorder.
Self-Medication Hypothesis
This theory posits that individuals with early signs of mental illness, including psychosis, may use substances such as cannabis to cope with their symptoms. However, substance use can further exacerbate their mental health issues, leading to a vicious cycle.
A young person experiencing early symptoms of psychosis might use cannabis to alleviate anxiety or distress but may increase their risk of developing more severe psychotic symptoms due to the drug’s effects on dopamine regulation.
de novo mutation hypothesis
This hypothesis suggests that new (de novo) genetic mutations, particularly in older fathers, contribute to the risk of developing psychosis in offspring.
These mutations are not inherited but arise spontaneously during reproduction, with paternal age being a key factor.
The hypothesis posits that as men age, the chances of de novo mutations in their sperm increase, which can contribute to developmental disorders, including schizophrenia, in their children.
Children born to fathers over the age of 35 are more likely to develop schizophrenia due to the higher rate of de novo mutations in sperm as men age.
The selection into late fatherhood hypothesis
The increased risk is due to other correlates of late fatherhood(e.g., old fathers perhaps are … different in …)
Self-medication hypothesis
- con of cannabis use
However, in individuals already vulnerable to psychosis, cannabis use can exacerbate symptoms by increasing dopamine activity in the brain, particularly in areas linked to psychosis. Studies have shown that cannabis use, especially in high doses, can increase the likelihood of developing psychotic disorders like schizophrenia. Therefore, while cannabis might offer short-term relief, it can also contribute to the onset or worsening of psychotic symptoms over time.
de novo mutation hypothesis
- biological mechanisms
These de novo mutations can disrupt normal brain development, potentially affecting genes related to neurodevelopment and increasing the risk of disorders like schizophrenia. The offspring may inherit errors in genetic blueprints that impair cognitive, social, or motor development, contributing to the likelihood of psychotic disorders later in life.
A child born to a 45-year-old father may have a higher risk of developing schizophrenia due to the accumulation of genetic mutations in the father’s sperm over time. These mutations might affect brain development in ways that predispose the child to psychotic disorders.
