The Monoamine Hypothesis Flashcards
What are monoamines?
A group of neurotransmitters containing amino acid
Which monoamines is the hypothesis concerned with?
Noradrenaline, Seretonin, Dopamine
What suggests that monoamines are involved?
Antidepressents raise the levels of them and in some cases this solves depression
How is seretonin said to be involved?
It is carried across the synapse to the post synaptic neuron by a transporter. Changes in the gene encoding of this transporter could lead to low seretonin
What causes the changes in the seretonin transporters?
Stress
Where are seretonin recepetors found?
In the central nervous system cells
What is the role of seretonin?
To regulate other neurotransmitters
What happens if seretonin doesn’t regulate neurotransmitters?
Erractic brain functioning and faulty thinking patterns occur
How does erratic brain functioning and faulty thinking patterns explain depression?
Many people with depression have inappropriate guilt and feelings of unnecessary worthlessness which is a result of faulty thinking patterns
What can low levels of seretonin produce?
Low levels of noradrenaline
What is noradrenaline required for?
To show alertness, energy, anxiety and attention to life
How do low levels of noradrenaline link to depression?
Depressed people often suffer from hypersomnia where they sleep excessively due to lack of energy, low noradrenaline can reduce energy
What do some antidepressents work to do?
Some increase noradrenaline, some increase dopamine
What is the role of dopamine?
It is related to the ability to show attention and motivation, pleasure and reward
What do low levels of dopamine explain in terms of depression?
why some people have a markedly diminished interest in activities as they don’t have dopamine to give them the feeling of pleasure
How does Versiani et al (1999) support the monoamine hypothesis?
A double blind trial of noradrenaline reuptake inhibitors (NRIs) and a placebo found an increase in the mood of depressed patients with NRIs, supports that an increase of noradrenaline is needed
Why can drug research be problematic?
Because drugs containing monoamines might help treat depression but it doesn’t mean they caused it, it could be that environmental factors made NTs fall low
What is an opposing biological explanation?
That increased levels of cortisol in parts of the nervous system is implicated in depression suggesting the monoamine hypothesis is incorrect
What did Klimeck et al (1997) find when he compared the locus coeruleus of 15 dead patients with major depression with 15 who didn’t suffer?
The locus coeruleus is responsible for producing noradrenaline and they found differences in structure suggesting that this affects the production of NTs
What did McNeal and Cimbolic (1986) find?
That patients suffering from depression show lower levels of 5-H1AA than the non depressed, this is a chemical found when seretonin is broken down suggesting low levels
How does opipramol oppose the hypothesis?
It is a drug used to treat depression that has an action unrelated to monoamine neurotransmitters and suggests other factors are involved
What have MRI scans shown that oppose the hypothesis?
That there are physical differences in the brain in people with depression comapred to those without, these may cause depression e.g smaller hippocampus
