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Examining encephalon scans interpreted at various times of the year, scientists
have discovered that serotonin transporter activities, which help
regularize the neurotransmitter seratonin, variegate according to the season.
According to the article, released on September 1, 2008 in Archives
of General Psychiatry, one of the
JAMA/Archives journals, this regular variance could potentially lead to
explanations of seasonal affective disorder and it's mood swings.
The authors explain seasonality as it relates to mood: "It is a
common experience in temperate zones that individuals palpate happier and
more industrious on undimmed and sunny days and many go through a reject
in modality and vigor during the dark winter season." It has been
suggested that this is related to serotonin levels in the brain, as
this neurotransmitter is constitutional to functions such as mating, eating,
balance of energy, and sleep. The serotonin transporter binds to
serotonin, helping it exit the space between brain cells when the
communicate. This protein "is a key chemical element in
regulation intensity and spread of the 5-hydroxytryptamine signal," according to
the authors.
To investigate this relationship, Nicole
Praschak-Rieder, M.D., and Matthaeus Willeit, M.D., of the Centre for
Addiction and Mental Health and the University of Toronto, Ontario,
Canada, and colleagues examined 88 healthy adults, with an average eld
of 33 years, between 1999 and 2003. One�positron emission
imaging (PET) scan was performed on each subject to assess the
potential binding of serotonin transporter exploitation a measuring rod of denseness
of the transporter. If this economic value is higher, serotonin circulates less
in the psyche. the private scans were grouped according to the season
taken, into either fall and winter or spring and summer.
In the fall and wintertime scans, the measured value was higher. The
authors sum up: "Serotonin
transporter binding potential values were significantly higher in all
investigated brain regions in individuals investigated in the fall and
wintertime compared with those investigated in the spring and summer."
Matching the scans to meteorological data, higher values generally
occurred when fewer hours of sunlight were available in the day.
The authors note that this correlation coefficient may consume some comportment on mood:
"An
implication of greater serotonin car transporter binding in winter is that
this may ease extracellular 5-hydroxytryptamine loss during winter, leading
to lour mood," they say. They continue, "Higher regional serotonin
transporter ski binding potential values in fall and winter may explain
hyposerotonergic [related to to low-toned serotonin levels] symptoms, such as
deficiency of zip, fatigue, overeating and increased duration of sleep
during the non-white season."
In conclusion, they land, the implications of such results could be
very important for an sympathy of Seasonal Affective Disorder and
other related diseases: "These findings have authoritative
implications for understanding seasonal mood change in healthy
individuals, vulnerability to seasonal affective disorder and the
relationship of light exposure to mood... This offers a
possible explanation for the regular reoccurrence of depressive
episodes in fall and winter in some vulnerable individuals."
Seasonal Variation in Human Brain Serotonin Transporter Binding
Nicole Praschak-Rieder, MD; Matthaeus Willeit, MD; Alan A. Wilson, PhD;
Sylvain Houle, MD, PhD; Jeffrey H. Meyer, MD, PhD
Arch Gen Psychiatry. 2008;65(9):1072-1078.
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Written by Anna Sophia McKenney
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Saturday 6 September 2008
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