Seasonal affective disorder
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|Light therapy lamp for the treatment of seasonal affective disorder (SAD)|
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Synonyms and Keywords: SAD; seasonal disorder; seasonal depression; winter blues; winter depression
Seasonal affective disorder (SAD), also known as winter depression, is a form of depression that is correlated with changes in the season. In the most common form of SAD, an individual experiences more frequent depressive periods between the late fall and early spring, with no such instances in the late spring and summer months. Less commonly, patients may experience depressive episodes in the summer; this type of disorder is often referred to as reverse seasonal affective disorder.
SAD was first described during the 1980s by South African physician Normal Rosenthal, who noticed that he felt significantly less industrious and energetic during the winters following his move to the United States, though he returned to his normal state during the spring.
Rather than being defined as its own distinct disorder, SAD is classified as a specific type of depression that involves a persistent association between depressive episodes and seasonal changes.
Though the physiological basis of SAD is not completely clear, people with SAD seem to suffer from some of the following hormonal/neurotransmitter imbalances more frequently than the general population:
- Serotonin. Studies have shown that individuals suffering from winter-occurring SAD produce more serotonin transporter protein in the winter months than in the summer months, which means serotonin has less of an effect.
- Melatonin. In the winter, as days become shorter and periods of darkness lengthen, the production of melatonin increases. This can interfere with a patient’s circadian rhythm and induce lethargy and drowsiness.
- Vitamin D. Patients with SAD tend to have lower levels of vitamin D than their unaffected counterparts; this deficiency may play a role in exacerbating depression through interference with the action of serotonin.
Commonly co-morbid conditions include:
Differentiating seasonal affective disorder from other diseases
Epidemiology and Demographics
The prevalence of SAD ranges from 1.5% to 9%, depending on latitude.
SAD is most commonly diagnosed in young adults.
SAD is more common in women than in men. Women are four times as likely as men to be diagnosed with SAD.
No racial predilection for SAD has been observed.
- Being female
- Living far from the equator
- Having a family history of any type of depression
- Being a young adult
No formal screening guidelines exist for SAD. The Seasonal Pattern Assessment Questionnaire (SPAQ), developed by Rosenthal in 1984, is an effective, self-administered tool for patients who think they might be suffering from SAD.
Natural History, Complications, and Prognosis
- The age of onset of SAD is generally between 18 and 30 years.
- SAD can be a serious disorder and may necessitate hospitalization.
- With treatment, the prognosis of SAD is generally good, though some people with SAD continue to experience the full effects of the disorder throughout their lives.
A diagnosis of SAD is appropriate for patients who meet all of the criteria for a diagnosis of major depression and in whom the incidence of depression has been observed to correspond to the onset of specific seasons for a period of no less than two years.
- Feeling depressed a majority of the time
- Feeling hopeless or insignificant
- Losing interest in activities one previously enjoyed
- Having trouble sleeping
- Experiences changes in appetite or weight
- Having difficulty concentrating
- Having frequent thoughts of death or suicide
There is no formal, established test for SAD. A diagnosis is made by asking a patient about his/her history of symptoms.
No imaging findings are associated with SAD.
Other Diagnostic Studies
No other diagnostic modalities are associated with SAD.
- Options for the treatment of SAD include medication, light therapy, psychotherapy, and the administration of vitamin D.
- Any of these therapies may be used on its own or in combination with another.
- SAD may be treated with selective serotonin reuptake inhibitors (SSRIs). Bupropion, a type of SSRI, has been specifically approved by the FDA for the treatment of SAD.
- Common side effects of bupropion include drowsiness, anxiety, dry mouth, dizziness, weight loss, and sore throat.
- Common side effects of SSRIs include nausea, diarrhea, constipation, vomiting, dry mouth, weight changes, and headaches.
- SAD has been treated primarily with light therapy, also referred to as bright light therapy (BLT) or phototherapy, since the 1980s.
- The rationale behind the use of light therapy is that the depressive effect of decreased sunlight during the late fall and winter months can be counteracted through daily exposure to bright light.
- Patients who undergo light therapy typically use a light box each morning from early fall until the start of spring.
- The use of light boxes generally calls for between 20 and 60 minutes of exposure to 10,000 lux of cool-white fluorescent light, which is approximately 20 times greater in brightness than standard lighting.
- As evidence of the efficacy of light therapy as compared to other treatment options is far from conclusive, experts recommend that decisions about forms of treatment be guided greatly by the preferences of individual patients.
- Common side effects of light therapy include eye strain and headaches.
- Light therapy is contraindicated for individuals on photosensitizing medications.
- The use of psychotherapy, specifically cognitive behavioral therapy (CBT), to treat SAD is common.
- CBT helps patients recognize and replace depressing thoughts.
- Patients are also encouraged to engage in activities they find pleasing and engaging as a technique for coping with their symptoms.
- Though the administration of vitamin D has not been proven to be an effective treatment for SAD, researchers have postulated that it may be helpful due to decreased vitamin D levels observed in SAD patients.
- Studies intended to determine the efficacy of vitamin D as a treatment for SAD have yielded mixed results.
Surgery is not recommended for the management of SAD.
- There are no established measures for the primary prevention of SAD.
- Measures for the secondary prevention of SAD include:
- Getting an adequate amount of sleep
- Eating a healthy, balanced diet
- Taking medicine as directed
- Exercising regularly
- Avoiding alcohol and illegal drugs
- National Institute of Mental Health. “Seasonal Affective Disorder.” 2016. https://www.nimh.nih.gov/health/topics/seasonal-affective-disorder/index.shtml
- Melrose S (2015). "Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches.". Depress Res Treat 2015: 178564. doi:10.1155/2015/178564. PMID 26688752.
- Diagnostic and statistical manual of mental disorders : DSM-5. Washington, D.C: American Psychiatric Association. 2013. ISBN 0890425558.
- Lurie SJ, Gawinski B, Pierce D, Rousseau SJ (2006). "Seasonal affective disorder.". Am Fam Physician 74 (9): 1521-4. PMID 17111890.
- Nussbaumer B, Kaminski-Hartenthaler A, Forneris CA, Morgan LC, Sonis JH, Gaynes BN et al. (2015). "Light therapy for preventing seasonal affective disorder.". Cochrane Database Syst Rev (11): CD011269. doi:10.1002/14651858.CD011269.pub2. PMID 26558494.
- Avery, D H; Eder DN, Bolte MA, Hellekson CJ, Dunner DL, Vitiello MV, Prinz PN (2001). "Dawn simulation and bright light in the treatment of SAD: a controlled study". Biological Psychiatry 50 (3): 205-216 = id = 11513820. Retrieved on 2007-05-05.
- Modell, Jack; Rosenthal NE, Harriett AE, Krishen A, Asgharian A, Foster VJ, Metz A, Rockett CB, Wightman DS (2005). "Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL Biological Psychiatry" 58 (8): 658-667. 16271314.
- U.S. National Library of Medicine. MedlinePlus. “Seasonal affective disorder.” 2016. https://medlineplus.gov/ency/article/001532.htm
- U.S. National Library of Medicine. MedlinePlus. “Bupropion.” 2016. https://medlineplus.gov/druginfo/meds/a695033.html
- U.S. National Library of Medicine. MedlinePlus. “Sertraline.” 2016. https://medlineplus.gov/druginfo/meds/a697048.html