Sex Hormones and Schizophrenia Flashcards Preview

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Flashcards in Sex Hormones and Schizophrenia Deck (27)
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Define schizophrenia

A severe psychotic mental illness characterised by delusions, auditory hallucinations, thought disorder, odd behaviour, and progressive deterioration in personal, domestic, social, and occupational competence, all occurring in clear consciousness


Define hallucination

A perception in the absence of a stimulus


Define delusion

A fixed belief held firmly by an individual despite no rational evidence or evidence to the contrary, and which may not be in keeping with socio-cultural background


What is the lifetime prevalence of schizophrenia?



In which social groups is schizophrenia prevalence higher?

Urban areas, lower socio-economic classes, recent immigrants, prison populations


Describe the differences in schizophrenia in males and females

In males, onset is typically earlier (peak age of onset 10-25), with negative symptom impairment more likely and general outcome worse. In females, onset is typically later (25-35 then middle age, bimodal distribution) with negative symptom impairment less likely and general outcome better


In which population group is a paranoid presentation more common?

Young males


In which population group is a hebephrenic presentation more common?

Young people aged 16-25


Describe the 'rule of thirds' with schizophrenia

1/3 of patients suffer acute episodes but can lead a normal life in between without medication, 1/3 do not fully recover but their disease can be controlled with medication, and 1/3 are treatment resistant


Describe the pathology of schizophrenia

Decreased brain weight and volume, atrophy of the hippocampus, amygdala, and parahippocampal gyrus, enlaregd lateral and 3rd ventricles, reduced cortical grey matter


Describe the differences between schizophrenic and healthy brains on PET scans

Schizophrenics have decreased frontal lobe activation and increased temporal lobe activation


Describe the dopamine hypothesis of schizophrenia

The positive symptoms of schizophrenia are due to excess dopaminergic activity


Give some evidence for the dopamine hypothesis of schizophrenia

1) Amphetamines and levodopa cause positive symptoms in non-schizophrenics
2) All effective antipsychotics are D2 receptor antagonists


Describe the serotonin hypothesis of schizophrenia

Schizophrenia is due to excess serotoninergic activity


Give some evidence for the serotonin hypothesis of schizophrenia

1) LSD and psilocybin (5-HT receptor agonists) cause positive symptoms in non-schizophrenics
2) Newer antipsychotics are potent 5HT receptor antagonists


Describe the excitatory amino acid hypothesis of schizophrenia

Schizophrenia is caused by insufficient excitatory amino acids or their receptors


Give some evidence for the excitatory amino acid hypothesis of schizophrenia

1) Schizophrenic patients have low CSF glutamate and decreased glutamate receptors in their temporal lobes
2) A single dose of PDP (NMDA receptor antagonist) causes both positive and negative symptoms in non-schizophrenics


State some possible explanations for the sex differences in schizophrenia

Sexually dimorphic brain anatomy, disproportionately high incidence of birth injury in males, differential effects of androgens and oestrogens


State some evidence for oestrogen being protective against psychosis

Psychosis is less common in women, psychosis incidence is reduced during pregnancy then increased post-partum, risk is increased after menopause


How might oestrogen protect against psychosis? (Lindemar)

It may have a neuroleptic-like effect on the dopaminergic system and antagonise dopamine receptors. (Lindemar found this was beneficial in the short-term but potentially increased symptom incidence long-term)


Describe the effect of aromatase deficiency on mice

They develop apoptosis of their hypothalamic dopaminergic neurons


Define pre-pulse inhibition

A neurological phenomen where a weak stimulus received before a stronger stimulus reduces the intensity of the second response


Name 2 diseases with disrupted pre-pulse inhibition

Schizophrenia, Alzheimer's disease


How does pre-pulse inhibition help explain the gender difference in schizophrenia?

Males have a naturally higher pre-pulse inhibition so may be more vulnerable to its disruption


Describe the sexual dimorphism in midbrain dopaminergic circuitry (Crow, 1985)

In females, the hypothalamus must release oestrogen and progesterone in a cyclical manner - in males, hormone release can be constant


What starts the differentiation of the male brain in utero?

Testosterone surge at around 6 weeks


Describe the difference between activational and organisational sex differences

Organisational effects occur early (e.g. in utero), are irreversible, and are due to testosterone, whereas activational effects occur later, are due to oestrogen or oestradiol, and are thought to be reversible