Caspi et Al (2003)

Aim

To determine the possible role of the 5-HTT gene in depression
after experiences of stressful events.

Pricedure

Researchers compared participants with normal 5-HTT
gene with long alleles and a mutation of the 5-HTT gene
with shorter alleles. Both types are quite frequent in
humans but the longer allele is slightly more frequent
(57%).

Findings

The researchers found that participants who carried a
mutation of the 5-HTT gene and who had experienced
many stressful events were more likely to become
depressed after stressful events than those participants
who carried the normal 5-HTT gene.

Conclusions

Those with a mutated 5-HTT gene (short allele) are more genetically predisposed to traumatic events. However it is not forr certain that they will become depressed, and those with long alleles can also be depressed

Applications

because 5-HTT genes partake in control of serotonin levels which control mood, this experiment provides insight on the impact of genetics on behavior. Thus provoking scientists to research on how to prevent mutated alleles, or find other genes that have an impact on serotonin levels.

Evaluation +

-provides insight role of genetics on behaviour
-this info can help people make decisions accordingly if they know they are more predisposed to side effects of stressful events (they can talk to their doctor or psychiatrist)
-no participants were harmed
-longitudinal studies enabled researchers to observe participants over long periods of time

Evaluation -

-depending on the participants, debriefing process may cause them some grief, as they may feel that their depression is completely out of their control (something is wrong with them)
-those depressed may have felt uncomfortable throughout entire experiment
-even though their is positive correlation between short alleles and likelihood of depression, no specific cause and effect relationship could be established
-A great deal of further research (follow up studies) need to be done, before we can consider this specific gene as a significant cause in depression

Research study

-longitudinal study
(same participants participate in study for long period of time)

5-HTT gene

gene that plays a role in controlling serotonin (neurotransmitter) levels that effect mood

allele

variant form of gene