neuro: schizophrenia Flashcards

1
Q

what is major psychoses?

A

major psychoses ‘madness-cancer of mental illnesses’
examples: schizoaffective disorder = schizophrenia and bipolar
-delusional disorder
-some depressive and manic illnesses

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2
Q

why is schizophrenia important?

A

-happens early on- in adolescence
-quite prevalent
- disabling and chronic

schizophrenia is more related to thoughts compared to mood.
It is a mental state that is out of touch with reality
Abnormalities of perception thought and ideas
Profound alterations in behaviour

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3
Q

Prevalence of schizophrenia and some stats?

A
  • 1% of the population
    -no significant influence of culture ethnicity background etc
    -increased in urban areas
    -men show an earlier age onset higher behaviour to negative symptoms, co morbid substance abuse etc impart to women who display a late onset of behaviour with more affective symptoms.
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4
Q

Explain the three classes in which schizophrenia symptoms can be grouped

A
  • positive : hallucinations (visual and auditory)
  • delusions
    -disorganised thought
  • movement disorders

negative: social withdrawal
-anhedonia (disninterest or pleasure in life)
- poverty of speech
-emotional flatness

cognitive (happens later on) :
- impaired working memory
-impaired attention *
-impaired comprehension

2 or more of these symptoms must persist for at least6 months to be classed as schizophrenia

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5
Q

what are the four phases of schizophrenia?

A

1- the pro dome : late teens/early twenties - often mistaken for anxiety or depression

2- the active/acute phase: onset of positive symptoms
differentiation of what is and isn’t real becomes difficult

3- Remission: treatment —-> return to normality

4- relapse

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6
Q

how do we know that genes are involved in one of the causes of schizophrenia?

A
  • twins studies
    -homozygous twins have a 50% chance of developing schizophrenia if one twin is already diagnosed
    -heterozygous twins have a 14% chance if one twin is already diagnosed
    This tells us genes have involvement
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7
Q

what are candidate genes?

A

-genes that are the “risk” or. “ candidate genes” of schizophrenia: so if you have them it does not mean you will 100% have schizophrenia, but more risk

The genes associated with dopamine metabolism, have been associated with increasing risk of developing schizophrenia.

So scz is not directly inherited, but it can run in families
Candidate risk genes : gene deletion, gene mutation

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8
Q

what research has been shown to cause schizophrenia?

A
  • pregnancy birth complications during the influenza season
  • a Finnish study reported a spike in scz for people who were foetuses during the 1957 influenza epidemic
  • pregnant women in the uk are advised to be vaccinated against seasonal flu

Low birth weight, premature birth, asphyxia during birth

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9
Q

What are some environmental factors for schizophrenia?

A
  • pregnancy/birth complications
  • stress
  • drug use
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10
Q

what is the dopamine theory?

A

mesolimbic pathway: pathway for dopamine
dopamernergic neurones that project from the ventral tegmental area to the amygdala to the hippocampus and the nucleus accumbens where dopamine gets released

The dopamine theory says that hyper stimulation of this mesolimbic pathway, is a cause for the positive symptoms of scz (hallucinations, delusions etc)

However, hypo stimulation of the mesocrotical pathway that projects from the VTA to the frontal cortex, is associated with some of the negative symptoms of scz.

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11
Q

why do we think the dopamine theory of schizophrenia is correct?

A
  • you would expect the plasma and CSF dopamine levels to be higher, however there is no clear change in CSF concentration.
    -the reason why we think it’s correct is bc all of the anti psychotics work by blocking the dopamine d2 receptor, you get a decrease in positive symptoms of schizophrenia.
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12
Q

what is the difference in brain structure between someone with scz and someone without?

A

with scz:
- overall brain size slightly smaller
- reductions in grey matter
- enlarged lateral ventricles, smaller hippocampus
However nit all people with schizophrenia have such profound structural differences.

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13
Q

what is hypofrontality?

A

-state of decreased cerebral blood flow in the prefrontal cortex of the brain.
-this is seen with schizophrenic patients.
prefrontal cortex associated with decision making, which is why they find it hard to make decisions.

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14
Q

what is the association with glutamate and schizophrenia?

A

If you block the glutamate receptor (NMDA) with an NMDA antagonist (ex ketamine) , it is said to cause hallucinations ans thought disorders.
-they looked into the brains and found a low level of glutamate, and a low glutamate receptor density in the prefrontal cortex.
- experiment done on a mouse where the NMDA receptor expression was downregulated, they began to show the symptoms associated with schizophrenia.

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15
Q

how is serotonin related to schizophrenia?

A
  • evidence :
    LSD (which is a hallucinogen) is a partial 5HT agonist, which causes hallucinations. So blocking the serotonin receptor causes antipsychotic effects.
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16
Q

what is the main current theory summarised?

A
  • over stimulation of mesolimbic D2 receptors
  • hypoactivity of frontal cortical d1 receptors
  • reduced pre frontal glutaminergic activity
  • 5HT involved
17
Q

what is something that antipsychotics do?

A
  • a big reason as to why positive schizophrenic symptoms show, is due to the mesolimbic dopaminergjc pathway, an increase in dopamine causing hyper stimulation if the receptors. Therefore one thing thst antipsychotics do is block the dopamine d2 receptors and as a result it blocks the positive schizophrenic positive symptoms.
18
Q

discuss the two types of antipsychotics?

A

typical - known as first generation antipsychotic
- first developed in the 1950’s
-mainly antagonise D2 receptors
- they get rid of the positive symptoms, but not the negative and are said to have side effects, such as Parkinsonism type of symptoms

Atypical: also known as second generation
- back in the 1980’s
- they block the d2 receptors and the 5-HT-2a receptors.
-block negative and positive symptoms and have side effects (such as weight gain) , but nothing as severe as Parkinsonism type of symptoms.

19
Q

what are the dopamine pathways?

A

mesocortical pathway: (cognitive control, motivation and emotion. Ventral tegmental area to prefrontal cortex)

mesolimbic pathway: reward, projects to nucleus accumbens

nigostiatal pathway: movement, substantia nigra to striatum

tuberohypophyseal pathway: prolactin release, hypothalamus to pituitary.