THE ROUGH GUIDE TO PSYCHOLOGY
Longitudinal research in New Zealand has identified a specific gene
which, combined with traumatic life-events, increases the likelihood
that a person will develop depression later in life. Avshalom Caspi
at Duke University and his colleagues followed 1032 people from
Dunedin from the age of three until their twenty-sixth birthday and
paid particular attention to which forms of the 5-HTT transporter
gene they had – long or short. This gene is known to be involved in
the transmission of the brain-chemical serotonin, and the long form is
more efficient at doing its job.
For the small proportion of participants who experienced a bout of
depression without any personal trauma, it made no difference what form
of the 5-HTT gene they had. However, among those participants who had
suffered a personal trauma, having one or two short forms of the 5-HTT
transporter gene was associated with an increased risk of developing
depression, compared with having two long forms. The result appeared to
be a clear case of how a person’s genetic disposition interacting with their
life circumstances can influence their risk of mental illness.
This result from New Zealand and the fact that most modern anti-
depressants target the serotonin system have led to the popular theory
that depression somehow reflects a chemical imbalance in the brain, and
in particular a deficit in serotonin activity. However, critics of this idea
suggest it’s little more than “biobabble” – a myth deliberately propagated
by drug companies to help boost sales of antidepressants.
These critics point to the fact that paracetemol’s effectiveness at
alleviating headaches doesn’t mean that headaches are caused by lack
of paracetemol. They also point out that attempts to induce depres-
sion by lowering serotonin levels have failed, and conversely, that
directly boosting serotonin levels using high doses of tryptophan (the
amino acid processed by the body to make serotonin) has failed to
alleviate depression. In any case – so the argument goes – who is to
say what the “right” chemical balance is? Critical psychiatrists, such as
Joanna Moncrieff, claim that antidepressants exert their effects not by
correcting an imbalance but merely through non-specific effects such
as sedation or stimulation.
DOES DEPRESSION HAVE AN UPSIDE?
Another area of controversy concerns the evolutionary roots of
depression. Paul Andrews, an evolutionary psychologist at Virginia
Commonwealth University, and Anderson Thompson, a psychiatrist
based in Charlottesville, argue that depression is akin to fever, in the