-IBIS-1.5.0-
tx
endocrine system
seasonal affective disorder
diagnoses
definition and etiology
definition: Recurrent depressive episodes that occur yearly in the fall and/or winter seasons and remit spontaneously in the spring; aka "winter depression".
etiology: Although this syndrome is now being fully recognized as a valid disease, the physiologic pathways are still not well understood. The theories surrounding SAD focus on the absence of sunlight during the winter months (artificial indoor light is not a protective or therapeutic measure) causing hormonal imbalances in the patient's system, particularly pineal secretion of melatonin. Melatonin is secreted when there is little or no sunlight: when there is sunlight the secretion is inhibited.
Exactly how the decreased sunlight and associated increase in melatonin produces the signs and symptoms of SAD is presently unknown, although increased melatonin levels in the body have been associated with increased sleepiness.
Patients most likely to experience SAD are those living in temperate zones (with a lot of rainy, grey days), those with a depressive tendency, and those living far enough north to experience lengthy periods of darkness for many months of the year. The symptoms may begin as early as autumn (October) and end when the spring sun begins to shine (April-May).
signs and symptoms
The symptoms often begin gradually as the length of sunlight begins to diminish:
Sadness/depression.
Withdrawal/apathy.
Irritability.
Sleep disturbances: sleeping more and waking unrefreshed.
Decreased physical activity.
Weight gain.
Increased appetite.
lab findings:
At this time there appears to be no appropriate tests to confirm SAD.
course and prognosis
The illness produces recurrent episodes of depression that are likely to persist until the patient is treated with either light therapy or some other treatment that rebalances and desensitizes the patient to the normal decreased daily sunlight that occurs in fall and winter, thus eradicating the depressive periods at the source.
differential diagnosis
Although there are a multitude of other diseases that produce the signs and symptoms listed, the cyclical symptoms of this disorder are its key indicator.
footnotes