Article: Seasonal affective disorder

Seasonal affective disorder, or SAD, also known as winter depression is an affective, or mood disorder. Most SAD sufferers experience normal mental health throughout most of the year, but experience depressive symptoms in the winter. SAD is rare, if existent at all in the tropics, but is measurably present at latitudes of 30°N (or S) and higher.

Cause

Seasonal mood variations are believed to be related mostly to daylight, not temperature. For this reason, SAD is prevalent even in mid-latitude places with mild winters, such as Seattle. People that live in the Arctic region are especially susceptible due to the effects of polar nights. Prolonged periods of overcast weather can also exacerbate SAD. SAD is a serious disorder, sometimes triggering dysthymia or clinical depression. It may require hospitalization.

Norman Rosenthal, MD, pioneer in SAD research, has estimated that the prevalence of SAD in the adult US population is between 1.4 percent (in Florida) and 9.7 percent (in New Hampshire).

Various etiologies have been suggested.^[1] One possibility is that SAD is related to a lack of serotonin and that exposure to full-spectrum artificial light may improve the condition by stimulating serotonin production, although this has been disputed.^[2],[3] Another theory is that melatonin produced in the pineal gland is the primary cause,^[4],[5] since there are direct connections between the retina and the pineal gland. Some studies show that melatonin levels do not appear to differ between those with and without SAD. However, mice incapable of synthesizing melatonin appear to express "depression-like" behaviors^[6],[7] and melatonin receptor ligands produce antidepressant-like effect in mice^[8]. Light therapy appears to be effective in treating SAD, but the exact mechanism of the effect is still unknown.

Although Dr. Rosenthal first called this disorder "winter blues", this term is more often used to describe something felt by a greater number during the winter. This blue feeling can usually be dampened or extinguished by exercise and increased outdoor activity, particularly on sunny days, resulting in increased solar exposure. Connections between human mood, as well as energy levels, and the seasons are well-documented, even in healthy individuals. Particularly in high latitudes (50°N or S) it is common for people to experience lower energy levels during the winter. Colds and flu also peak during this time^{[citation needed]}, and most people get less outdoor exercise than in the summer.

Treatment

"Light boxes" can be purchased for those suffering from SAD. ^[9]

The most validated of the light therapies is the use of a bright light box at a dose of 10,000 lux for 30-60 minutes daily. The eyes should remain open and nearby during this time, but not directly staring at the lights. The best time to administer the therapy is currently in debate, though mornings have been suggested to mimic dawn. Light therapy may take several weeks to take full effect though some improvement should be noted within a week. Light therapy should be continued until natural daily light exposure becomes sufficient, usually during spring.

Medication is a more recent treatment and selective serotonin reuptake inhibitors (SSRIs) have proven effective in treating SAD. Examples of these antidepressants are fluoxetine (Prozac), sertraline (Zoloft, Lustral), or paroxetine (Paxil). ^[10]

Some studies have shown dawn simulation to be as effective as bright lights in treating SAD. ^[11] Others have shown 456-476 nanometer blue light to be effective.

History

Winter depression (or winter blues) is a common slump in the mood of Scandinavians. Doctors estimate that about 20% of all Swedes are affected, and it seems to be hereditary. It was first described by the 6th century Goth scholar Jordanes in his Getica where he described the inhabitants of Scandza (Scandinavia).

In the USA the diagnosis of seasonal affective disorder was first proposed by Norman E. Rosenthal, MD in 1984. Rosenthal wondered why he became muggish during the winter after moving from sunny South Africa to New York. He started experimenting increasing exposure to artificial light, and found this made a difference.

Famous sufferers

Famous sufferers of SAD include Miriam Taffel, renowned for her work in the fields of psychology and intelligent systems.

Jillian Barberie of Good Day L.A. has mentioned during the program that she suffered from SAD when she lived in Ontario, Canada.

Johnny Briggs, who played Mike Baldwin in Coronation Street, also suffers from SAD.

Musician Rick Strom has credited his most creative periods to SAD.

Norman E. Rosenthal, MD, first researcher into the effect of light upon mood.

See also

• Depression
• Human factors
• Human reliability
• Modafinil
• Nootropic
• Shift work sleep disorder
• Treatments
  • Light box
  • Vitamin D
  • Cod liver oil
  • Shark liver oil

Notes

1. ^ Seasonal affective disorder: autumn onset, winter gloom - board review
2. ^ Johansson C, et al. (2001) Seasonal affective disorder and serotonin-related polymorphisms. Neurobiol Dis. 8(2):351–7.
3. ^ Johansson C, et al. (2003) The serotonin transporter promoter repeat length polymorphism, seasonal affective disorder and seasonality. Psychol Med. 33(5):785–92.
4. ^ The Merck manual
5. ^ National mental health association article
6. ^ Prolonged swim-test immobility of serotonin N-acetyltransferase (AANAT)-mutant mice
7. ^ Reliability assessment of an automated forced swim test device using two mouse strains
8. ^ The antidepressant-like effect of the melatonin receptor ligand luzindole in mice during forced swimming requires expression of MT2 but not MT1 melatonin receptors
9. ^ UBC FAQ for SAD
10. ^ SAD information from the WSC Counseling Center
11. ^ Avery DH et al. (2001) Dawn simulation and bright light in the treatment of SAD: a controlled study. Biol Psychiatry. 50(3):205–16.