The Biological Explanation for Depression (Clinical Psychology)

Question 1

What is the Monoamine Hypothesis for Depression?

Answer 1

Proposes that depression results from a chemical imbalance in the serotonin and noradrenaline (monoamine neurotransmitters) in the brain.

Question 2

What was the Problem with the Monoamine Hypothesis?

Answer 2

However, although the levels of noradrenalin and serotonin increase within hours of the administration of these antidepressant drugs, the symptoms often do not improve for a period of up to six weeks in some cases.

This challenged the simple monoamine hypothesis and led to a more complex alternate explanation

Question 3

What is the More Complex Biological Explanation of Depression?

Answer 3

Suggests that low levels of noradrenalin and serotonin causes an up-regulation in the sensitivity of the receptor sites on the synapses in relevant pathways.

Because of the low levels of serotonin and noradrenalin, there is too little stimulation of postsynaptic receptors.

Therefore, in order to compensate more receptors are made, but when more of the neurotransmitter becomes available through the administration of antidepressant drugs, there is a down-regulation where the receptors are desensitized.

Question 4

What have more recent theories suggested about depression?

Answer 4

They’ve refined the idea that depression results from a pathological alteration in receptor sites caused by too little stimulation by monoamine neurotransmitters.

They now look in more detail at the interaction between serotonin and noradrenalin.

• In this explanation, serotonin controls the levels of noradrenalin so when there are low levels of serotonin, the levels of noradrenalin are affected.
  
  • If these are too low then the person will experience feelings of depression. if too high then they may experience mania (as in bipolar depression).

Question 5

What is Serotonin?

Answer 5

A chemical created by the body that works as a neurotransmitter. It is responsible for managing moods.

Question 6

What is Noradrenalin?

Answer 6

(also known as norepinephrine) is a catecholamine hormone and neurotransmitter with multiple roles including maintaining concentration.

Question 7

What are Receptor Sites?

Answer 7

Areas on the postsynaptic neuron that allow neurotransmitters to lock onto the membrane.

Question 8

What is Down-Regulation?

Answer 8

A homeostatic mechanism where the brain produces less of something in response to an increase.

Question 9

What research Supports the Biological Explanation of Depression?

Answer 9

(Most evidence comes from drug research)

• Versaini et al
• Andreoli et al

Question 10

What Drug Research supports the Biological Explanation of Depression?

Answer 10

MDMA (ecstasy) increases the amount of serotonin in the synaptic gap, and are associated with a feeling of euphoria.

• Supports the link between high/low serotonin and high/low mood SSRIs/NRIs block the reuptake of monoamines, and support the link.

Question 11

What is the issue with using drug research to support the Biological Explanation of Depression?

Answer 11

Drug research can be problematic in that, because of drug is effective in treating a disorder, it doesn’t mean indicates the cause of the disorder.

Question 12

How does Versaini et al support the Biological Explanation of Depression?

Answer 12

They did a double-blind trial with NRIs and a placebo. They found a marked mood improvement in depressed patients.

Question 13

How does Andreoli et al support the Biological Explanation of Depression?

Answer 13

They found that antidepressants that increased noradrenaline levels are just as effective as those that increase serotonin levels.

Question 14

What was found about NRIs that Challenge the Biological Explanation of Depression?

Answer 14

NRIs are not successful for all depressed patients.

Question 15

What research Challenges the Biological Explanation of Depression?

Answer 15

• Perez et al
• Sullivan
• Neale + Kendler

Question 16

How does Perez et al challenge the Biological Explanation of Depression?

Answer 16

They bred mice lacking the gene for tryptophan (enzyme precursor of serotonin production). They didn’t show any signs of depression; they weren’t respondending to antidepressants; and when put under stress, the mice didn’t respond any differently to normal mice (Animal Studies).

Question 17

Is the Biological Explanation of Depression Credible?

Answer 17

Yes.

Serotonin + noradrenaline levels in synapses can be objectively measured with PET scans.

Question 18

What is Treatment Aetiology Fallacy?

Answer 18

We assume that if a treatment is effective in reducing symptoms, the target of the treatment must be the cause of the disorder. However, this isn’t the case: because serotonin + noradrenalin can be treated with antidepressants, it doesn’t prove they cause it

Question 19

How does Sullivan, Neale + Kendler challenge the Biological Explanation of Depression?

Answer 19

They undertook a meta-analysis of family, twin, and adoption studies.

They found a 40% increased risk of developing depression when a 1st-degree relative has it.

• This suggests genetic vulnerability to neurotransmitter dysfunction, rather than neurochemicals.