NEURO: Schizophrenia Flashcards
What is schizophrenia?
It’s when you’re in a state of distorted perception. This is not limited to visual information.
It affects 1% of the population. It’s onset is in early adulthood. Men tend to be more affected than women.
What are the three classes into which schizophrenia symptoms can be grouped?
POSITIVE (an increase in abnormal behaviours):
- Hallucinations (e.g. visual, auditory)
- Delusions
- Disorganised thought/speech
- Movement disorders
NEGATIVE (an absence of normal behaviours):
- Social withdrawal
- Anhedonia (inability to feel pleasure at pleasurable activities)
- Lack of motivation
- Poverty of speech
- Emotional flatness
COGNITIVE (problems with thought processes):
- Impaired working memory
- Impaired attention
- Impaired comprehension
Two or more of these symptoms must persist for at
least 6 months to be classed as schizophrenia.
What could be the causes of schizophrenia?
There are genetic factors:
- SCZ isn’t directly inherited, but can ‘run in families’
- ‘Candidate’ risk genes: gene deletions, gene mutations
There are environmental factors:
- Pregnancy/birth complications
- Stress
- Drug use
It is due to both nature and nurture that schizophrenia develops.
What are some of the candidate genes for schizophrenia?
Examples of some of these genes is:
- COMT
- DISC1
- GRM3
Possessing these abnormal genes does not mean you will definitely get schizophrenia – similarly, some people who have schizophrenia do not have these genetic abnormalities.
How can pregnancy/birth complications cause schizophrenia?
A Finnish study reported a spike in schizophrenia for people who were foetuses during the 1957 influenza epidemic. Thus, pregnant women in the UK are advised to be vaccinated against seasonal flu.
Low birth weight, premature birth, and asphyxia during birth are all causes of early-life stress (stemming from birth complications).
Give some examples of stress that can cause schizophrenia.
- MOVING COUNTRY: Swedish cohort 1 first-degree relative further increased risk
- LOSS OF JOB/HOME/RELATIONSHIP
- PHYSICAL/EMOTIONAL/SEXUAL ABUSE
The mechanism by which stress may trigger schizophrenia is unknown.
How can drug abuse lead to schizophrenia?
Continued cannibas use during early life for ~15 years has been shown to increase the risk of schizophrenia development.
Other drugs that could are:
- amphetamine
- cocaine
- LSD
What are the two main hypotheses for the pathophysiology of schizophrenia?
There is the:
- dopamine hypothesis
- glutamate hypothesis
There are many other hypotheses:
- Brain structure differences
- Hypofrontality
- Inhibitory interneuron dysfunction
- Kynurenic Acid
- Oxidative Stress
- Immune System Abnormalities
Describe the dopamine hypothesis.
Schizophrenia is associated with abnormally high dopaminergic transmission.
However, there is no conclusive evidence that dopamine levels are increased in schizophrenia.
Are we treating the symptoms via a mechanism different to the cause?
Describe the evidence for and against the dopamine hypothesis.
FOR:
- both amphetamine and cocaine block the reuptake of dopamine and foster the symptoms of schizophrenia
- amphetamine promotes the release of dopamine and fosters symptoms of schizophrenia
AGAINST:
- chlorpromazine, a drug that blocks symptoms of schizophrenia, occupies the dopamine site on the D2 receptor, preventing receptor activation by dopamine
Describe the evidence for the glutamate hypothesis.
- the NMDA receptor number has been found to be reduced in post-mortem brains with schizophrenia
- NMDA receptor antagonists (such as ketamine, PCP) exacerbate (make worse) the psychosis
- NMDA receptor antagonists can induce psychosis
What are the different types of treatment for schizophrenia?
- Pharmacological (current + future therapies?)
- Cognitive Behavioural Therapy (CBT)
- Electroconvulsive therapy (ECT)
What are the types of antipsychotics taken for schizophrenia?
There are two types: TYPICALS: - Also known as ‘first generation’ - First developed in the 1950s - Mainly antagonise D2 receptors
ATYPICALS:
- Also known as ‘second generation’
- First developed in the 1980s
- Mainly antagonise D2 and 5-HT2A receptors
As a recap, describe the different dopamine pathways and what they are responsible for.
MESOCORTICAL PATHWAY: cognitive control and motivation and emotion
MESOLIMBIC PATHWAY: reward
NIGROSTRIATAL PATHWAY: movement
TUBEROHYPOPHYSEAL PATHWAY: prolactin release
Describe typical antipsychotics.
The four key types of typical antipsychotics:
- Chlorpromazine
- Fluphenazine
- Haloperidol
- Flupentixol
The effect takes days to develop.
They are only effective in treating the positive symptoms. They can induce some severe side-effects.
