Seasonal patterns of illness have been recognized since ancient times, but the concept of seasonality in psychiatric disorders has only gained prominence in the past two decades. This article will briefly review the diagnosis, treatment and pathophysiology of winter seasonal affective disorder (SAD).
Diagnostic and Clinical Features
The DSM-IV-TR diagnostic criteria classify SAD as a subtype or "course specifier" for recurrent major depressive episodes within major depressive disorder or bipolar disorder (BD). However, only a minority of patients are diagnosed as having BD (Lam, 1998b).
The stability of the SAD diagnosis is similar to other depressive subtypes. Longitudinal studies of one to 10 years of follow-up showed that about 30% of patients continued to have seasonal episodes, about 20% were in remission (some because of treatment) and the remaining 50% had complex patterns that were not strictly seasonal (Schwartz et al., 1996; Thompson et al., 1995). Like other forms of depression, SAD is associated with significant morbidity and health service utilization (Eagles et al., 2002).
Although not included in the diagnostic criteria, SAD is also associated with so-called atypical vegetative symptoms, including carbohydrate craving, increased appetite, weight gain and hypersomnia/morning fatigue (Lam, 1998b; Oren and Rosenthal, 1992; Winkler et al., 2002) (Table). While these symptoms are also found in atypical depression, the rejection sensitivity commonly seen in atypical depression is not prominent in SAD (Tam et al., 1997). Atypical symptoms appear to be predictive of good response to light therapy (Terman et al., 1996).
Studies using the Seasonal Pattern Assessment Questionnaire (SPAQ) estimated the prevalence of winter SAD in North America to be approximately twice that of Europe (Mersch et al., 1999). The differences between North American and European studies may be related to translation issues with the SPAQ, cultural response biases, genetic differences in seasonality, climatic variation or other factors. Regardless, studies using the SPAQ are likely to overestimate the prevalence of SAD because clinical diagnoses are not obtained.
Community studies using diagnostic interviews estimated the prevalence of SAD by DSM-III-R or DSM-IV criteria as 2.6% in Ontario, Canada (Levitt and Boyle, 2002), and 0.4% in the United States (Blazer et al., 1998). Seasonal affective disorder is more prevalent with higher (more northern) latitudes, but the correlation between latitude and prevalence is modest (Levitt and Boyle, 2002; Mersch et al., 1999).
Light therapy. An early meta-analysis of over two dozen studies using fluorescent light boxes found that bright light treatment was superior to control conditions (Terman et al., 1989). However, these findings were criticized for methodological limitations, including small sample sizes and use of dim light as placebo controls.
Avery DH, Dahl K, Savage MV et al. (1997), Circadian temperature and cortisol rhythms during a constant routine are phase-delayed in hypersomnic winter depression. [Published erratum Biol Psychiatry 42(7):636.] Biol Psychiatry 41(11):1109-1123.
Avery DH, Eder DN, Bolte MA et al. (2001), Dawn simulation and bright light in the treatment of SAD: a controlled study. Biol Psychiatry 50(3):205-216.
Bauer M, Whybrow PC, Angst J et al. (2002), World Federation of Societies of Biological Psychiatry (WFSBP) Guidelines for biological treatment of unipolar depressive disorders, part 1: Acute and continuation treatment of major depressive disorder. World Journal of Biological Psychiatry 3:5-43.
Blazer DG, Kessler RC, Swartz MS (1998), Epidemiology of recurrent major and minor depression with a seasonal pattern. The National Comorbidity Survey. Br J Psychiatry 172:164-167 [see comment].
Depue RA, Arbisi P, Krauss S et al. (1990), Seasonal independence of low prolactin concentration and high spontaneous eye blink rates in unipolar and bipolar II seasonal affective disorder. Arch Gen Psychiatry 47(4):356-364.
Eagles JM, Howie FL, Cameron IM et al. (2002), Use of health care services in seasonal affective disorder. Br J Psychiatry 180:449-454 [see comment].
Eastman CI, Gallo LC, Lahmeyer HW, Fogg LF (1993), The circadian rhythm of temperature during light treatment for winter depression. Biol Psychiatry 34(4):210-220.
Eastman CI, Young MA, Fogg LF et al. (1998), Bright light treatment of winter depression: a placebo-controlled trial. Arch Gen Psychiatry 55(10):883-889 [see comments].
Gallin PF, Terman M, Reme CE et al. (1995), Ophthalmologic examination of patients with seasonal affective disorder, before and after bright light therapy. Am J Ophthalmol 119(2):202-210.
Kogan AO, Guilford PM (1998), Side effects of short-term 10,000-lux light therapy. Am J Psychiatry 155(2):293-294.
Kripke DF (1998), Light treatment for nonseasonal depression: speed, efficacy, and combined treatment. J Affect Disord 49(2):109-117.
Lam RW, ed. (1998a), Seasonal Affective Disorder and Beyond. Light Treatment for SAD and Non-SAD Conditions. Washington, D.C.: American Psychiatric Press.
Lam RW (1998b), Seasonal affective disorder: diagnosis and management. Primary Care Psychiatry 4(2):63-74.
Lam RW, Gorman CP, Michalon M et al. (1995), Multicenter, placebo-controlled study of fluoxetine in seasonal affective disorder. Am J Psychiatry 152(12):1765-1770.
Lam RW, Levitan RD (2000), Pathophysiology of seasonal affective disorder: a review. J Psychiatry Neurosci 25(5):469-480.
Lam RW, Levitt AJ, eds. (1999), Canadian Consensus Guidelines for the Treatment of Seasonal Affective Disorder. Vancouver, Canada: Clinical and Academic Publishing.
Lam RW, Tam EM, Grewal A, Yatham LN (2001a), Effects of alpha-methyl-para-tyrosine-induced catecholamine depletion in patients with seasonal affective disorder in summer remission. Neuropsychopharmacology 25(5 suppl):S97-S101.
Lam RW, Tam EM, Shiah IS et al. (2000), Effects of light therapy on suicidal ideation in patients with winter depression. J Clin Psychiatry 61(1):30-32.
Lam RW, Tam EM, Yatham LN et al. (2001b), Seasonal depression: the dual vulnerability hypothesis revisited. J Affect Disord 63(1-3):123-132.
Lam RW, Zis AP, Grewal A et al. (1996), Effects of rapid tryptophan depletion in patients with seasonal affective disorder in remission after light therapy. Arch Gen Psychiatry 53(1):41-44.
Lee TM, Chan CC (1999), Dose-response relationship of phototherapy for seasonal affective disorder: a meta-analysis. Acta Psychiatr Scand 99(5):315-323.
Levitt AJ, Boyle MH (2002), The impact of latitude on the prevalence of seasonal depression. Can J Psychiatry 47(4):361-367.
Lewy AJ, Bauer VK, Cutler NL, Sack RL (1998a), Melatonin treatment of winter depression: a pilot study. Psychiatry Res 77(1):57-61.
Lewy AJ, Bauer VK, Cutler NL et al. (1998b), Morning vs evening light treatment of patients with winter depression. Arch Gen Psychiatry 55(10):890-896 [see comments].
Lewy AJ, Sack RL, Miller LS, Hoban TM (1987), Antidepressant and circadian phase-shifting effects of light. Science 235(4786):352-354.
Lewy AJ, Sack RL, Singer CM et al. (1988), Winter depression and the phase-shift hypothesis for bright light's therapeutic effects: history, theory, and experimental evidence. J Biol Rhythms 3(2):121-134.
Mersch PP, Middendorp HM, Bouhuys AL et al. (1999), Seasonal affective disorder and latitude: a review of the literature. J Affect Disord 53(1):35-48.
Neumeister A, Konstantinidis A, Praschak-Rieder N et al. (2001a), Monoaminergic function in the pathogenesis of seasonal affective disorder. Int J Neuropsychopharmacol 4(4):409-420.
Neumeister A, Praschak-Rieder N, Besselmann B et al. (1997), Effects of tryptophan depletion on drug-free patients with seasonal affective disorder during a stable response to bright light therapy. Arch Gen Psychiatry 54(2):133-138.
Neumeister A, Turner EH, Matthews JR et al. (1998), Effects of tryptophan depletion vs catecholamine depletion in patients with seasonal affective disorder in remission with light therapy. Arch Gen Psychiatry 55(6):524-530.
Neumeister A, Willeit M, Praschak-Rieder N et al. (2001b), Dopamine transporter availability in symptomatic depressed patients with seasonal affective disorder and healthy controls. Psychol Med 31(8):1467-1473.
Oren DA, Levendosky AA, Kasper S et al. (1996), Circadian profiles of cortisol, prolactin, and thyrotropin in seasonal affective disorder. Biol Psychiatry 39(3):157-170.
Oren DA, Rosenthal NE (1992), Seasonal affective disorders. In: Handbook of Affective Disorders, Paykel ES, ed. London: Churchill Livingstone, pp551-567.
Oren DA, Wisner KL, Spinelli M et al. (2002), An open trial of morning light therapy for treatment of antepartum depression. Am J Psychiatry 159(4):666-669.
Partonen T, Magnusson A, eds. (2001), Seasonal Affective Disorder. Practice and Research. New York: Oxford University Press.
Pinchasov BB, Shurgaja AM, Grischin OV, Putilov AA (2000), Mood and energy regulation in seasonal and non-seasonal depression before and after midday treatment with physical exercise or bright light. Psychiatry Res 94(1):29-42.
Ruhrmann S, Kasper S, Hawellek B et al. (1998), Effects of fluoxetine versus bright light in the treatment of seasonal affective disorder. Psychol Med 28(4):923-933.
Schwartz PJ, Brown C, Wehr TA, Rosenthal NE (1996), Winter seasonal affective disorder: a follow-up study of the first 59 patients of the National Institute of Mental Health Seasonal Studies Program. Am J Psychiatry 153(8):1028-1036.
Schwartz PJ, Murphy DL, Wehr TA et al. (1997), Effects of meta-chlorophenylpiperazine infusions in patients with seasonal affective disorder and healthy control subjects. Diurnal responses and nocturnal regulatory mechanisms. Arch Gen Psychiatry 54(4):375-385.
Tam EM, Lam RW, Robertson HA et al. (1997), Atypical depressive symptoms in seasonal and non-seasonal mood disorders. J Affect Disord 44(1):39-44.
Teicher MH, Glod CA, Magnus E et al. (1997), Circadian rest-activity disturbances in seasonal affective disorder. Arch Gen Psychiatry 54(2):124-130.
Terman M, Amira L, Terman JS, Ross DC (1996), Predictors of response and nonresponse to light treatment for winter depression. Am J Psychiatry 153(11):1423-1429.
Terman JS, Terman M, Lo ES, Cooper TB (2001), Circadian time of morning light administration and therapeutic response in winter depression. Arch Gen Psychiatry 58(1):69-75.
Terman M, Terman JS, Quitkin FM et al. (1989), Light therapy for seasonal affective disorder. A review of efficacy. Neuropsychopharmacology 2(1):1-22.
Terman M, Terman JS, Ross DC (1998), A controlled trial of timed bright light and negative air ionization for treatment of winter depression. Arch Gen Psychiatry 55(10):875-882 [see comments].
Thompson C (2002), Light therapy in the treatment of seasonal and non-seasonal affective disorders: A meta-analysis of randomised controlled trials. S4.4. Presented at the International Society for Affective Disorders Conference. March 9-12; Taormina, Sicily, Italy.
Thompson C, Childs PA, Martin NJ et al. (1997), Effects of morning phototherapy on circadian markers in seasonal affective disorder. Br J Psychiatry 170:431-435.
Thompson C, Raheja SK, King EA (1995), A follow-up study of seasonal affective disorder. Br J Psychiatry 167(3):380-384.
Wehr TA, Duncan WC Jr, Sher L et al. (2001), A circadian signal of change of season in patients with seasonal affective disorder. Arch Gen Psychiatry 58(12):1108-1114 [see comment].
Winkler D, Willeit M, Praschak-Rieder N et al. (2002), Changes of clinical pattern in seasonal affective disorder (SAD) over time in a German-speaking sample. Eur Arch Psychiatry Clin Neurosci 252(2):54-62.
Wirz-Justice A, Graw P, Krauchi K et al. (1993), Light therapy in seasonal affective disorder is independent of time of day or circadian phase. Arch Gen Psychiatry 50(12):929-937.
University of British Columbia SAD Info Page. Available at: www.psychiatry.ubc.ca/mood/sad. Accessed Sept. 9.
Society for Light Treatment and Biologicial Rythms. Available at: www.sltbr.org. Accessed Sept. 9.
Centre for Environmental Therapeutics. Available at: www.cet.org. Accessed Sept. 9.