A
link between depression and decreased serotonin
(5-HT) reuptake by the transporter (SERT) has
been established. There is also an association
between the deletion of the
5-HT transporter long promoter region
(5-HTTLPR) in the SERT gene with a decrease in
5-HT reuptake. In contrast, an enhancement of
extracellular levels of 5-HT has been linked
with an increase in temperature. A recent study
investigated the body temperature of depressed
patients and normal subjects with the 5-HTTLPR
deletion.
A group of 125 individuals (46 normal controls,
79 outpatients diagnosed with major depression
according to the Structured Clinical Interview
for Psychiatric Diagnoses), taking no
psychotropic drugs, were enrolled in the study.
Eighty-one 81 (13 controls, 68 depressed) were
genotyped for 5-HTTLPR polymorphisms. Body
temperature was determined following a strict
oral protocol using single, cross-sectional,
naturalistic time-of-day measurements.
In depressed patients, uncorrected body
temperatures were higher than in controls, and
when age and time-of-day were corrections were
applied the difference was found. Depressed or
normal, subjects with the 5-HTTLPR deletion
(short SERT allele) had a higher temperature
than those without the short allele on either
chromosome.
These results show that major depression is
associated with an increased daytime body
temperature, and the higher the temperature the
more likely the subjects are to be depressed.
This study supports the suggestion that
depression may include an inflammation
component. It seems also that a link exists
between body temperature and genetic differences
in 5-HT transport, although temperature
differences between depressed patients and
normal controls do not only originate from the
5-HTTLPR deletion. Neuropsychobiology
47: 120-127, 2003