Trillian's Depression Page

Seasonal Affective Disorder (SAD)

What is SAD?

SAD stands for Seasonal Affective Disorder.

Animals react to the changing season with changes in mood and behavior and human beings are no exception. Most people find they eat and sleep slightly more in winter and dislike the dark mornings and short days.

Some people though have more severe bouts of feeling down all the time, low energy, problems with sleep and appetite, and reduced concentration to the point where they have difficulty functioning at work or in the home. We say that these people have a clinical depression , to distinguish it from everyday ups and downs. Seasonal affective disorder (affective is a psychiatric term for mood), or SAD, describes people who have these clinical depressions only during the autumn and winter seasons. During the spring and summer, they feel well and "normal".

The common symptoms of SAD include:

1. periods of depression & normal mood that accompany seasonal changes
2. recurrent episodes of depression in certain months of the year usually surface in childhood or adolescence
3. insomnia
4. carbohydrate craving
5. weight gain
6. decreased sexual appetite
7. lethargy
8. hopelessness
9. suicidal thoughts
10. social withdrawal
11. summer depression (decreased appetite, weight loss, constant agitation or anxiety)
12. winter depression (between October/November & March/April. Depressions are usually mild to moderate, but can be severe.)
13. strong reactions to changes in environmental light (react poorly to overcast days & decreased indoor lighting)
14. walking around the house turning on lights

Symptoms And Diagnosis

The validity of SAD as a diagnosis has received attention because of the impending publication of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) [2,3*]. Draft diagnostic criteria for seasonal pattern (Table 1) were revised according to empiric data and consensus in the field [4*]. SAD continues to be classified as a 'seasonal pattern' for unipolar and bipolar mood disorders, and is included as one of several 'course specifiers' of the major mood disorders (along with rapid cycling and post partum).

Although SAD is defined by the pattern of depressive episodes in DSM-IV, Allen et al [5**] confirmed previous reports that so called atypical depressive symptoms of hypersomnia, hyperphagia, and weight gain were more frequently found in SAD patients compared to matched nonseasonal patients. They also determined family psychiatric history in first-degree relatives using the Family History Method. The genetic loading for mood disorders (of unspecified seasonality) was similar for both seasonal and nonseasonal patients, but the SAD patients were more likely to have alcoholism in their families.

advertisement

The similarity of symptoms between SAD and atypical depression prompted studies of the clinical overlap between the two diagnoses. Pande et al [6] found high seasonality scores in 30 patients with defined atypical depression: 63% had seasonality scores in the range of SAD or 'subsyndromal' SAD. Conversely, Terman and Stewart [7] also found high rates of cardinal symptoms of atypical depression (mood reactivity and rejection sensitivity) in a cohort of SAD patients. Previous attempts at treating nonseasonal patients with atypical depression with light therapy were negative [8], but these reports suggest further study is indicated.

Who does it affect?

Researchers believe that SAD results from the shorter daylength in winter. Recent studies estimate that SAD is more common in northern countries because the winter day gets shorter as you go farther north. In Florida, less than 1% of the general population have SAD, while in Alaska as many as 10% of people may suffer from winter depression. In B.C., 2% to 5% of people probably have SAD. This means that up to 200,000 people in British Columbia may have difficulties in the winter due to significant clinical depression. Across the world the incidence increases with distance from the equator, except where there is snow on the ground when it becomes less common. More women than men are diagnosed as having SAD. Children and adolescents are also vulnerable.

What causes it?

The problem stems from the lack of bright light in winter. Researchers have proved that bright light makes a difference to the brain chemistry, although the exact means by which sufferers are affected is not yet known. It is not a psychosomatic or imaginary illness.

Psychobiology of SAD

Despite the heuristic appeal of a circadian hypothesis for SAD, there are as yet no consistently replicated data to support abnormal circadian rhythms as an etiology for SAD or for the therapeutic effects of light [34]. One study did not find abnormalities of CSF norepinephrine, serotonin, or dopamine activity [35*] in SAD patients, although other studies have shown changes in peripheral noradrenergic measures [36]. Using a challenge paradigm, the NIMH group have shown consistently different behavioral responses to the serotonergic agent, m-CPP, in SAD patients compared to matched controls [37*,38*], suggesting that serotonin dysregulation is a fruitful area for further study.

Retinal mechanisms have been proposed as an etiology of SAD. Using flash electroretinography, Lam et al [39*] found reduced b-wave amplitudes in female SAD patients, but not in males. Ozaki et al [40**] replicated the finding of reduced electrooculographic (EOG) ratios in SAD. These results support a hypothesis of reduced retinal light sensitivity in SAD [41]. In contrast, Oren et al [42*] did not find differences in a number of different electrophysiologic measures of ophthalmologic function.

In preliminary brain imaging studies, Cohen et al [43*] studied seven winter SAD patients with positron emission tomography (PET) and found abnormalities in the prefrontal and parietal cortex areas. In another PET study of nine patients with a summer pattern of SAD, abnormalities were noted in the orbital frontal cortex and in the left inferior parietal lobule [44]. These interesting findings will need replication in a larger sample of subjects.

Treatment

1. SAD is often misdiagnosed as a viral infection
2. Light therapy
   • bright or fluorescent light reduces winter depression symptoms
   • reduces the level of the neurotransmitter melatonin normally present at night
   • 2 hours of treatment in the morning (light at night causes insomnia)
   • side effects may result (irritability, eye strain, headaches, mania)
   • schedule time outdoors in sunlight each day
3. antidepressant medications (Elavil & Imipramine)
4. monoamine exidase inhibitors (MAOIs) (Nardil & Parnate)
5. lithium

top | light therapy | lithium | depression index

home | bipolar disorder | my diary | depression types | medications
quotes, humor, poetry