Seasonal affective disorder

Infobox_Disease
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Caption = Light therapy lamp for Seasonal Affective Disorder
DiseasesDB = 11910
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MedlinePlus = 001532
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MeshID = D016574
Seasonal affective disorder (SAD), also known as winter depression, is a mood disorder in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter or, less frequently, in the summer [ [http://query.nytimes.com/gst/fullpage.html?res=9C03E4DA103AF930A2575BC0A9649C8B63&sec=health Seasonal Depression can Accompany Summer Sun] . Ivry, Sara. "The New York Times". Retrieved September 6, 2008] , repeatedly, year after year. The US National Library of Medicine notes that "some people experience a serious mood change when the seasons change. They may sleep too much, have little energy, and crave sweets and starchy foods. They may also feel depressed. Though symptoms can be severe, they usually clear up." [ [http://www.nlm.nih.gov/medlineplus/seasonalaffectivedisorder.html U.S. National Library of Medicine] ] The condition in the summer is often referred to as Reverse Seasonal Affective Disorder, and can also include heightened anxiety. [ [http://www.mayoclinic.com/health/seasonal-affective-disorder/DS00195/DSECTION=2 Seasonal Affective Disorder by Mayo Clinic] ]

There are many different treatments for classic ("winter"-based) seasonal affective disorder, including light therapies with bright lights, anti-depression medication, ionized-air receptionFact|date=September 2008, cognitive-behavioral therapy and carefully-timed supplementation of the hormone melatonin.

Pathophysiology

Seasonal mood variations are believed to be related to light. An argument for this view is the effectiveness of bright light therapy.cite journal | last = Lam |first = RW |coauthors = Levitt AJ, Levitan RD, Enns MW, Morehouse R, Michalak EE, Tam EM |title = The Can-SAD Study: a randomized controlled trial of the effectiveness of light therapy and fluoxetine in patients with winter seasonal affective disorder |journal = American Journal of Psychiatry |volume = 163 |issue = 5 |year = 2006 | accessdate = 2007-05-12 | pmid = 16648320 |pages = 805–812 |doi = 10.1176/appi.ajp.163.5.805 ] SAD is measurably present at latitudes in the Arctic region, such as Finland (64º 00´N) where the rate of SAD is 9.5%cite journal | last = Avery |first = D H |coauthors = Eder DN, Bolte MA, Hellekson CJ, Dunner DL, Vitiello MV, Prinz PN |title =Dawn simulation and bright light in the treatment of SAD: a controlled study | journal = Biological Psychiatry |volume = 50 |issue = 3 |year = 2001 |pages = 205–216 | pmid = 11513820 | accessdate = 2007-05-05 |doi =10.1016/S0006-3223(01)01200-8] Cloud cover may contribute to the negative effects of SAD.cite journal |last = Modell |first = Jack |coauthors = Rosenthal NE, Harriett AE, Krishen A, Asgharian A, Foster VJ, Metz A, Rockett CB, Wightman DS | title = Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL Biological Psychiatry |volume = 58 |issue = 8 |year = 2005 |pages = 658–667 | pmid = 16271314]

SAD can be a serious disorder and may require hospitalization. There is also potential risk of suicide in some patients experiencing SAD. One study reports 6-35% of sufferers required hospitalization during one period of illness. The symptoms of SAD mimic those of dysthymia or clinical depression. At times, patients may not feel depressed, but rather lack energy to perform everyday activities. Norman Rosenthal, a pioneer in SAD research, has estimated that the prevalence of SAD in the adult United States population is between about 1.5 percent in Florida and about 9 percent in the northern US.

Various etiologies have been suggested. One possibility is that SAD is related to a lack of serotonin, and serotonin polymorphisms could play a role in SAD, [cite journal |last = Johansson |first = C | coauthors = Smedh C, Partonen T, Pekkarinen P, Paunio T, Ekholm J, Peltonen L,Lichtermann D, Palmgren J, Adolfsson R, Schalling M |title = Seasonal affective disorder and serotonin-related polymorphisms |journal = Neurobiology of Disease |volume = 8 |issue = 2 |year = 2001 |pages = 351–357 |accessdate = 2007-05-05 | pmid = 11300730 |doi = 10.1006/nbdi.2000.0373 ] although this has been disputed. [cite journal |last = Johansson |first = C |coauthors = Willeit M, Levitan R, Partonen T, Smedh C, Del Favero J, Bel Kacem S, Praschak-Rieder N,Neumeister A, Masellis M, Basile V, Zill P, Bondy B, Paunio T, Kasper S, Van Broeckhoven C, Nilsson LG,Lam R, Schalling M, Adolfsson R. |title = The serotonin transporter promoter repeat length polymorphism, seasonal affective disorder and seasonality |journal = Psychological Medicine |volume = 33 |issue = 5 |year = 2003 | pages = 785–792 |accessdate = 2007-05-05 | pmid = 12877393 |doi = 10.1017/S0033291703007372] Mice incapable of turning serotonin into N-acetylserotonin (by Serotonin N-acetyltransferase) appear to express "depression-like" behaviors, and antidepressants such as fluoxetine increase the amount of the enzyme Serotonin N-acetyltransferase, resulting in an antidepressant-like effect. [cite journal |last = Uz |first = T |coauthors =Manev, H |title = Prolonged swim-test immobility of serotonin N-acetyltransferase (AANAT)-mutant mice |journal = Journal of Pineal Research |volume = 30 |year = 2001 |pages = 166–170 | pmid = 11316327 |doi = 10.1034/j.1600-079X.2001.300305.x] Another theory is that the cause may be related to melatonin which is produced in dim light and darkness by the pineal gland, since there are direct connections, via the retinohypothalamic tract and the suprachiasmatic nucleus, between the retina and the pineal gland.

Subsyndromal Seasonal Affective Disorder is a milder form of SAD experienced by an estimated 14.3% vs. 6.1% of the U.S. population.cite journal |last = Avery | first = D. H. | pmid = 11328240 | coauthors = Kizer D, Bolte MA, Hellekson C |title = Bright light therapy of subsyndromal seasonal affective disorder in the workplace: morning vs. afternoon exposure |journal = Acta Psychiatrica Scandinavica |volume = 103 | issue = 4 |year = 2001 | pages = 267–274 | accessdate =2007-05-12 |doi = 10.1034/j.1600-0447.2001.00078.x ] The blue feeling experienced by both SAD and SSAD sufferers can usually be dampened or extinguished by exercise and increased outdoor activity, particularly on sunny days, resulting in increased solar exposure.cite journal | last = Leppämäki |first = Sami |coauthors = Haukka J, Lonnqvist J, Partonen T | title = Drop-out and mood improvement: a randomised controlled trial with light exposure and physical exercise | journal = BMC Psychiatry |volume = 4 |issue = 22 |year = 2004 | pmid = 15306031 | url = |accessdate = 2007-05-12 | doi = 10.1186/1471-244X-4-22 | pages = 22 ] Connections between human mood, as well as energy levels, and the seasons are well-documented, even in healthy individuals.

Diagnostic criteria

The Mayo Clinic [ [http://www.mayoclinic.com/health/seasonal-affective-disorder/DS00195/DSECTION=2 Seasonal Affective Disorder by Mayo Clinic] ] describes three types of Seasonal Affective Disorder, each with its own set of symptoms.According to the American Psychiatric Association, [cite book |last= Gabbard |first= Glen O |authorlink= |editor= |others= |title= Treatment of Psychiatric Disorders |origdate= |origyear= |origmonth= |url= |format= |accessdate= |accessyear= |accessmonth= |edition= Third edition, Volume 2 |series= |volume= |date= |year= |month= |publisher= American Psychiatric Publishing |location= Washington, DC |language= |isbn= |oclc= |doi= |id= |pages= p.1296 |chapter= |chapterurl= |quote= ] for a diagnosis to qualify as SAD, it must meet four criteria: depressive episodes at a particular time of the year; remissions or mania/hypomania also at a characteristic time of year; these patterns must have lasted two years with no nonseasonal major depressive episodes during that same period; and these seasonal depressive episodes outnumber other depressive episodes throughout the patient's lifetime.

Treatment

There are many different treatments for classic ("winter"-based) seasonal affective disorder, including light therapies, medication, ionized-air reception, cognitive-behavioral therapy and carefully timed supplementation of the hormone melatonin.

Bright light treatment is common although up to 69% of patients find it inconvenient and as many as 19% of patients stop use because of this. A specially designed lamp, many times brighter than normal indoor lighting, is placed near the sufferer, and has proven to be effective at doses of 2500 - 10,000 lux. Most treatments use 30-60 minute treatments, however this varies depending on the situation. The sufferer sits a prescribed distance, commonly 30-60 cm, in front of the box with her/his eyes open but not staring at the light source. Many patients use the light box in the morning, however it has not been proven any more effective than any other time of day. Discovering the best schedule is essential. Dawn simulation has also proven to be effective; in some studies, there is an 83% better response when compared to other bright light therapy. When compared in a study to negative air ionization, bright light was proven to be 57.1% effective vs. dawn simulation, 49.5%.cite journal | last = Terman | first = M. |coauthors = Terman, J.S. | title = Controlled Trial of Naturalistic Dawn Simulation and Negative Air Ionization for Seasonal Affective Disorder | journal = American Journal of Psychiatry |volume = 163 |issue = 12 |year = 2006 |pages = 2126–2133 | accessdate = 2007-05-12 |url = http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17151164&query_hl=7&itool=pubmed_docsum |id = 17151164 | doi = 10.1176/appi.ajp.163.12.2126 | pmid = 17151164] Patients using light therapy can experience improvement during the first week, but increased results are evident when continued throughout several weeks. Most studies found it effective without use year round, but rather as a seasonal treatment lasting for several weeks until frequent light exposure is naturally obtained.

SSRI (selective serotonin reuptake inhibitor) antidepressants have proven effective in treating SAD. Bupropion is also effective as a prophylactic. Effective antidepressants are fluoxetine, sertraline, or paroxetine. [cite journal |last = Moscovitch |first = A |url = http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=14504682&query_hl=3&itool=pubmed_docsum | coauthors = Blashko CA, Eagles JM, Darcourt G, Thompson C, Kasper S, Lane RM |title = A placebo-controlled study of sertraline in the treatment of outpatients with seasonal affective disorder |journal = Psychopharmacology |volume = 171 |year = 2004 |pages = 390–397 | accessdate = 2007-05-12 |doi = 10.1007/s00213-003-1594-8] Both fluoxetine and light therapy are 67% effective in treating SAD according to direct head-to-head trials conducted during the 2006 CAN-SAD study. [cite journal | last = Lam | first = Raymond W. | coauthors = Anthony J. Levitt, Robert D. Levitan, et al | year = 2006 | month = May | title = The Can-SAD Study: A Randomized Controlled Trial of the Effectiveness of Light Therapy and Fluoxetine in Patients With Winter Seasonal Affective Disorder | journal = Am J Psychiatry | volume = | issue = 163 | pages = 805-812 | publisher = | issn = | pmid = | doi = | bibcode = | oclc =| id = | url = http://day-lights.com/light-therapy-news/downloads/can-sad-study-wp.pdf | format = PDF, full text | accessdate = 2008-09-30 | laysummary = | laysource = | laydate = | quote = ] Subjects using the light therapy protocol showed earlier clinical improvement, generally within one week of beginning the clinical treatment.

Negative air ionization, involving the release of charged particles into the sleep environment, has also been found effective with a 47.9% improvement. Depending upon the patient, one treatment (ie. lightbox) may be used in conjunction with another therapy (ie. medication). Modafinil may be also an effective and well-tolerated treatment in patients with seasonal affective disorder/winter depression. [ Modafinil treatment in patients with seasonal affective disorder/winter depression: an open-label pilot study, Journal of affective disorders, 2004 Aug;81(2):173-8. ]

Alfred J. Lewy of Oregon Health and Science University in Portland, OHSU, and others see the cause of SAD as a misalignment of the sleep-wake phase contra the period of the body clock, circadian rhythms out of synch, and treat it with melatonin in the afternoon. Correctly timed melatonin administration shifts the rhythms of several hormones en bloc. [cite journal
last = Bhattacharjee | first = Yudhijit
date = 14 September 2007
title = Is Internal Timing Key to Mental Health?
journal = ScienceMag | volume = 317 | pages = 1488–90
publisher = AAAS | location = | issn = | doi = | bibcode = | oclc = | id = | url = http://www.ohsu.edu/ohsuedu/academic/som/images/Al-Lewy-Science.pdf
format = PDF | accessdate = 2008-02-18]

Incidence

Nordic countries

"Winter depression" is a common slump in the mood of some inhabitants of most of the Nordic countries. It was first described by the 6th century Goth scholar Jordanes in his "Getica" wherein he described the inhabitants of Scandza (Scandinavia). [Jordanes, "Getica," ed. Mommsen, "Mon. Germanae historica, V," Berlin, 1882.] Iceland, however, seems to be an exception. A study of more than 2000 people there found the prevalence of seasonal affective disorder and seasonal changes in anxiety and depression to be unexpectedly "low" in both sexes. [cite journal | quotes = | last = Magnusson | first = Andres | coauthors = Axelsson, Johann; Karlsson, Mikael M.; Oskarsson, Högni | year = 2000 | month = February | title = Lack of Seasonal Mood Change in the Icelandic Population: Results of a Cross-Sectional Study | journal = Am J Psychiatry | volume = 157 | pages = 234–238 | publisher = American Psychiatric Association | url = http://ajp.psychiatryonline.org/cgi/content/full/157/2/234 | format = | accessdate = 2007-11-27 | quote = | doi = 10.1176/appi.ajp.157.2.234 | pmid = 10671392 ] The study's authors suggested that propensity for SAD may differ due to some genetic factor within the Icelandic population. A study of Canadians of wholly Icelandic descent also showed low levels of SAD.cite journal |author=Magnússon A, Axelsson J |title=The prevalence of seasonal affective disorder is low among descendants of Icelandic emigrants in Canada |journal=Arch. Gen. Psychiatry |volume=50 |issue=12 |pages=947–51 |year=1993 |pmid=8250680 |doi=] It has more recently been suggested that this may be attributed to the large amount of fish traditionally eaten by Icelandic people, 225 lb per person per year as opposed to about 50 in the US and Canada, rather than to genetics. [cite journal | last = Cott | first = Jerry | coauthors = Joseph R. Hibbeln | year = 2001 | month = February | title = Lack of Seasonal Mood Change in Icelanders | journal = Am J Psychiatry | volume = 158 | issue = 158 | pages = 328 | publisher = American Psychiatric Association | url = http://ajp.psychiatryonline.org/cgi/content/full/158/2/328 | format = Letter to the Editor | accessdate = 2008-09-02 | quote = Thus, high levels of fish consumption should be considered a potential etiology for the finding of a lack of seasonal affective disorder among the Icelandic population. ]

Other countries

In the United States, a diagnosis of seasonal affective disorder was first proposed by Norman E. Rosenthal, MD in 1984. Rosenthal wondered why he became sluggish 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. In Alaska it has been established that there is a SAD rate of 8.9%, and an even greater rate of 24.9% [ [http://www.britebox-sad-lamps.com/sad-study-latitude.php Seasonal Affective Disorder and Latitude] ] for subsyndromal SAD. American science fiction-fantasy author Barbara Hambly had undiagnosed SAD for many years and speaks freely about her condition. [ [http://www.andromedaspaceways.com/inter_0002.htm Andromeda Spaceways interview with Barbara Hambly, discusses SAD] ]

Around 20% of Irish people are affected by SAD, according to a survey conducted in 2007. The survey also shows women are more likely to be affected by SAD than men. [ [http://www.breakingnews.ie/ireland/mhmhojididid/ BreakingNews.ie - "One in five suffers from SAD"] ] An estimated 10% of the population in the Netherlands suffers from SAD. [ [http://www.elsevier.nl/web/gezondheidgezin/donkeredagenwinterdepressieverklaard.htm/ Elsevier - Dark Days: Winter Depression (in Dutch, easy to translate to English with google translate (or anything like that)] ]

AD and Bipolar

Most people with SAD experience unipolar depression, but as many as 20% may have or may go on to develop a bipolar or manic-depressive disorder. It is important to discriminate the improved mood associated with recovery from the winter depression and a manic episode because there are important treatment differences. [ [http://www.mooddisorderscanada.ca/depression/sad.htm SAD and depression] ] In these cases, persons with SAD may experience depression during the winter and hypomania in the summer.

ee also

* Depression (mood)
* Circadian rhythm sleep disorder
* Wilson's Thyroid Syndrome

References

External links

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* [http://query.nytimes.com/gst/fullpage.html?res=9C03E4DA103AF930A2575BC0A9649C8B63&sec=health&spon=&pagewanted=2 Seasonal Depression Can Accompany Summer Sun] Reverse SAD article at [http://www.nytimes.com The New York Times]
* [http://scienceblogs.com/clock/2006/12/seasonal_affective_disorder_th.php Seasonal Affective Disorder - The Basics] on ScienceBlogs
* [http://www.consumerreports.org/health/free-highlights/manage-your-health/winter_depression.htm Consumer Reports article on SAD.]