Major depressive disorder (MDD) imposes an incredible burden on the individual, his or her family, and the community (CDC, 2011). MDD increases the mortality of the individual through both a 20-fold greater prevalence of suicide and a higher risk of cardiovascular death (CDC, 2011). Even the risk of death by all causes is doubled (Lepine & Briley, 2011). Using the World Health Organizations disability adjusted life-years (DALY) measurement, MDD ranked fourth in 1991 and third in 2004, and it is projected to be the leading cause of disease burden worldwide by 2030 (Lepine & Briley, 2011). The rate of reoccurrence of MDD is as high as 60% after five years and 85% after 15 years (DSM 5, 2013). Not surprisingly, the Institute of Medicine (IOM) named MDD a priority condition (IOM, 2001).
Seasonal affective disorder (SAD) is a subtype of recurrent MDD (DSM 5, 2013). SAD generally presents with a pattern of depressive episodes beginning in late fall and resolving in early spring (DSM 5, 2013). SAD is the only psychiatric illness with a predictable time of onset and remission (Partonen & Pandi-Perumal, 2010). Each year, about 0.5 – 3% of people in North America meet criteria for SAD and 7.5 to 20% experience subsyndromal symptoms (DSM 5, 2013). Women and young adults living in northern latitudes are most likely to be effected, and the typical patient is a 38 year old married woman with 10 previous episodes of winter depression (Lam & Tam 2009 p.12).
Center for Disease Control and Prevention. (2011). Mental illness surveillance among adults in the united states [Supplemental material]. Morbidity and Mortality Weekly Report, 60, 1-32.
Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM 5). (2013). Washington, DC: American Psychiatric Association.
Institute of Medicine. (2001). Crossing the quality chasm: A new health system for the 21st century. Washington, DC: National Academies Press.
Lepine, J. & Briley, M. (2011). The increasing burden of depression [Supplemental material]. Neuropsychiatric Disease and Treatment, 7, 3-7. doi: 10.2147/NDT.S19617