Better Understanding of "Winter Blues"
< Sep. 10, 2008 > --
Researchers in Canada think that fluctuations in serotonin transporter levels
may explain why many people suffer the winter blues.
Seasonal affective disorder, or SAD, is a mood disorder
characterized by depression related to a certain season of the year - especially
winter. However, SAD is often not described as a separate mood disorder but as a
"specifier," referring to the seasonal pattern of major depressive episodes that
can occur within major depression and manic depression.
In the first study of its kind, the team at the Centre for
Addiction and Mental Health (CAMH) in Toronto, Ontario, used positron emission
tomography (PET) to determine that brain levels of serotonin transporters are
significantly higher in fall/winter than in spring/summer.
PET is a type of nuclear medicine procedure. These studies
evaluate the metabolism of a particular organ or tissue, so that information
about the physiology (functionality) and anatomy (structure) of the organ or
tissue is evaluated, as well as its biochemical properties.
Serotonin is involved in regulating emotional functions
such as mood and energy levels, and physical functions such as eating and energy
balance.
Serotonin transporters remove serotonin, so the findings
suggest there is more serotonin removal in the fall/winter than in the
spring/summer, say the researchers. They also found that higher serotonin
transporter binding (the process that removes serotonin) values occur at times
when there is less sunlight.
The study - the first to identify seasonal differences in
brain levels of serotonin transporter levels - may help improve understanding of
seasonal mood changes in healthy people, vulnerability to seasonal affective
mood disorders, and the relationship of light exposure to mood.
This is "an important lead in understanding how season
changes serotonin levels. This offers an explanation for why some healthy people
experience low mood and energy in the winter, and why there is a regular
re-occurrence of depressive episodes in fall and winter in some vulnerable
individuals. The next steps will be to understand what causes this change and
how to interfere with it," study author Dr. Jeffrey Meyer says.
"Over the following years, we intend to determine the
specifics of the environment [such as light exposure] that influence serotonin
transporter levels so as to determine what is the optimal environment to prevent
illness. In the future, it may be that just like we have lifestyle
recommendations to prevent heart disease, we will have lifestyle recommendations
to prevent major depressive disorder," Dr. Meyer says.
Always consult your physician for more information.
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Seasonal affective disorder (SAD) is a clinical
diagnosis accepted in the medical community. Dr. Norman E. Rosenthal, Chief
of Environmental Psychiatry Branch of the National
Institute of Mental Health, is the researcher credited with
discovering SAD.
Onset usually occurs during adulthood (with the average
onset occurring at approximately age 23), and is four times more likely to
affect women than men. According to the National
Mental Health Disorders Association, approximately 10 percent to 20
percent of the population suffers from mild winter SAD, and nearly 5 percent
suffer from a more severe form of the disorder.
Two seasonal patterns of symptoms have been identified
with SAD: a fall-onset type, also called "winter depression," in which major
depressive episodes begin in the late fall to early winter months and remit
during the summer months, and a spring-onset type, also called "summer
depression," in which the severe depressive episode begins in late spring to
early summer.
The following are the most common symptoms of SAD.
However, each individual may experience symptoms differently. Symptoms may
include:
- increased sleep and daytime drowsiness
- irritability
- fatigue, or low energy level
- decreased sex drive
- diminished concentration
- difficulty thinking clearly
- increased appetite, especially for sweets and carbohydrates causing
weight gain
Always consult your physician for more information.
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