First 407 words of the document:
Serotonin is the synaptic transmitter in SYMPTOMS
a group of cells in the brain stem. It has
axons spread throughout the brain into Intense feelings of sadness and guilt.
the cortex, the cerebellum and the Difficulty in initiating actions and making decisions.
spinal cord. Low levels of serotonin Loss of energy or restlessness.
result in fewer nerve impulses travelling Disturbance of sleep.
around the brain, suppressing the Irrational hopelessness.
overall brain activity. Frequent negative thoughts, low self-esteem.
GENETICS AND DEPRESSION
Scientists have found a gene (5-HTT) which
appears to be linked to the production of
serotonin in the brain. The gene codes for a
reuptake protein that enables serotonin to be
CAUSES taken back into the presynaptic membrane after
release into the synapse.
Depression occurs due to problems with
serotonin in the brain. It can be triggered as a
DEPRESSION People who are homozygous for the `short' form
result of external factors such as relationship Depression is an affective disorder. The causes of seem most likely to experience depression after
stress or bereavement, or can be purely the depression are complex and not fully understood. experiencing stressful events. Heterozygotes have
result of chemical changes in the brain. an immediate risk and those homozygous for the
Dopamine and noradrenalin may also play a `long' form have a very low risk of depression.
role. People who have homozygote long forms produce
more reuptake proteins than heterozygotes who
produce more than homozygous short forms.
Talking therapies can help a patient to come to terms with adverse life events QUESTIONS
Use of drugs SSRIs (selective serotonin reuptake inhibitors) inhibit the reuptake proteins
in the presynaptic membrane, so that more serotonin remains in the synaptic cleft, more 1. What is the function of serotonin?
2. What effect does low serotonin levels have on the brain?
impulses travel along the post-synaptic axon to relieve the symptoms.
3. How does MAOB help sufferers of depression?
Neurotransmitters Tricyclic antidepressants (TCAs) increase the levels of serotonin and 4. Which is the most successful treatment for depression and why?
noradrenalin in the brain. Monoaminoxidase inhibitors inhibit the enzymes which usually 5. Why is it difficult to determine the causes of depression?
cause the breakdown of neurotransmitters in the synapses of the brain.