Schizophrenia: Biological Explanations - THE DOPAMINE HYPOTHESIS Flashcards
What is dopamine?
a neurotransmitter made in the brajn
What does dopamine play a role in?
plays a role in the “reward centre” of the brain
What functions is dopamine involved in?
- memory
- movement
- motivation
- mood
What assumption is the explanation of schizophrenia based on?
base on the biological assumption that neurotransmitters cause behaviour
What will happen if there are abnormalities in the way neurotransmitters are produced?
then this will lead to abnormalities in functioning and behaviour
What did research into from the 1950s on Parkinson’s Disease find?
- found that drugs that increased the levels of dopamine in the brain reduced Parkinson’s symptoms
- however it was also observed that when people were given these drugs, they developed schizophrenic-like symptoms
How was the idea that high levels of dopamine cause schizophrenia supported?
the idea was further supported by research into amphetamines
- this is a type of drug that is used recreationally to increase energy levels by increasing levels of dopamine
Griffiths et al:
- what drug?
- what did he find?
found that when people were given dextroamphetamine (an amphetamine), they quickly developed paranoid delusions and a cold, detached, emotionless demeanour
McKetin et al (2013):
- what did he find?
people who use amphetamines recreationally have reported psychotic-like side effects, including paranoia and mood disturbances
Curran et al (2004):
- what did he find?
found that when people who have schizophrenia use amphetamines, their symptoms worsen
Why was the initial dopamine hypothesis criticised?
How was is confirmed?
- for being too simplistic
- confirmed by the fact that giving drugs that lowered dopamine had no effect on those experiencing mainly negative symptoms
Why was the original dopamine hypothesis complicated?
by the important discovery of different types of dopamine receptor sites in different parts of the brain
Where were dopamine receptor sites discovered?
2 main areas of the brain?
- the mesolimbic pathway
- the mesocortial pathway
Where is the mesolimbic pathway?
- a nerve pathway in the limbic system in the brain
- begins in the ventral regimental area (VTA) and ends in the nucleus acumbens
What symptoms and state are in the mesolimbic pathway?
positive symptoms are thought to be associated with a HYPERdopaminergic state in the mesolimbic pathway
What is too much dopamine in the mesolimbic pathway caused by and what does it cause?
- caused by neurons either firing too quickly or too often
- causes overstimulation and positive symptoms such as hallucinations
What is poverty of speech linked to and where?
there is an excess of dopamine in the Broca’s area of the brain and it is thought that this may be linked to poverty of speech
Where is the mesocortial pathway?
- a nerve pathway that begins in the limbic system and ends in the cortex (the outer layer of the brain)
Where does the mesocortial pathway carry signals too and from?
carries signals from the VTA to the frontal lobe
What is the frontal lobe involved in?
- planning
- decision-making
What is the mesocortial pathway vital for?
- emotional responses
- emotions
- cognition
What symptoms and state are thought to be linked to the mesocortial pathway?
negative symptoms are thought to be associated with a HYPOdopaminergic state in the mesocortial pathway
What is too little dopamine evident in?
too little dopamine is evident in dopamine receptors in the frontal lobe of many people with cognitive impairments and negative symptoms of schizophrenia
