Seasonal Affective Disorder
Diagnosis is usually made using the criteria defined in the American Psychiatric Association’s (APA) Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM 5). Seasonal affective disorder is actually a subtype of either Major Depressive Disorder (MDD) or bipolar disorder, and it is documented by using the “seasonal pattern” modifier. Similar in quality and severity to MDD, these seasonal depressive episodes typically strike in the fall months and resolve by early spring. Each year, up to 3% of people in North America meet criteria for SAD and 7.5 to 20% experience subsyndromal symptoms ( APA, 2013). In America, prevalence peaks at 9.7% in New Hampshire and declines to 1.4% in Florida ( Roecklein & Rohan, 2005). 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). During the symptomatic months, SAD shares the same burden of illness as MDD. Major depression 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). The World Health Organization projects that MDD will be the leading cause of disease burden worldwide by 2030. Not surprisingly, the Institute of Medicine named MDD a priority condition. In general, clinicians fail to recognize SAD, thereby missing chances to alleviate the associated suffering. A large-scale study conducted by Rosenthal found that individuals with SAD have suffered and average of 13 prior seasonal depressive episodes before receiving treatment ( Rosenthal, 2013). Healthcare providers must remain alert to emerging depression as the winter approaches and remember that light therapy is a safe, effective, and cost-efficient treatment for SAD. The Hamilton Depression Rating Scale (HAM-D) is the most frequently used standardized assessment for depression. The SIGH-SAD is a version of the HAM-D which emphasizes the atypical symptoms of depression. This tool can aid in diagnosing and monitoring SAD. Patient-rated and clinician rated SIGH-SAD scores are positively correlated, therefore, patients can complete the SIGH-SAD independently prior to their appointment.
Bright Light Therapy
To normalize patients’ melatonin levels, Rosenthal and colleagues began exposing their patients to artificial light to simulate longer summer days. Due to the success of these initial trials, the psychiatrists organized, conducted, and published a pilot study in 1984 ( Rosenthal et al., 1984). This groundbreaking article defined SAD and coined the term “bright light.” The APA recommends light therapy as the first-line treatment and supports its use as a safe alternative or adjunct to antidepressant medication ( Gelenberg et al., 2010). Light therapy uses full-spectrum ultraviolet-filtered white light to therapeutically target symptoms of SAD. Remission rates for light therapy are equivalent to antidepressant medication with milder side effects ( Golden et al., 2005). Due to the chronic nature of this illness, light therapy presents a cost saving and environmentally mindful method of treatment compared with generic and non-generic medication ( Cheung et al., 2012). When prescribing bright light therapy, a mental health provider needs to consider the:
- Brightness of the light (measured in lux);
- Timing of light exposure;
- Duration of light exposure;
- Color of the light; and
- Wavelength of the light
Collectively, light therapy research indicates that 10,000 lux ultraviolet-filtered white light exposure for 30 minutes in the early morning reduces symptoms of SAD. Light devices that meet these specifications include Carex Day-Light Classic, Lightphoria, and NatureBright Sun Light. The exact distance the patient should position themselves from the device varies by manufacturer and will be included in the instructions. Usually this distance ranges from 18 to 36 inches. The therapeutic effect of light therapy occurs through the eyes, therefore patients should keep their eyes open but without looking directly at the light ( Golden et al., 2005). Side effects include headache, nausea, and eye strain, which can be mitigated by sitting farther from the light box ( Terman & Terman, 2005). Generally these side effects are significantly more tolerable than side effects from antidepressant medication. Although extremely rare, case reports have identified mania, hypomania, or suicidal ideation as associated risks; therefore, providers should closely monitor patients with a history of bipolar disorder for emerging mood lability ( Chan, Lam & Perry, 1994; Lam et al., 2000; Praschak-Rieder et al., 1997; Schwitzer et al., 1990). Initiation of treatment can begin after a diagnosis of SAD is confirmed and both the provider and the patient discuss the risks, benefits, and side effects. SAD usually begins in late October and remits in late April; however, this timing varies from patient to patient. Be sure to educate the patient on where to purchase a credible light therapy light device. After initiating treatment, the psychiatric provider may follow-up with the patient after two to four weeks to monitor for symptom improvement. Providers should encourage patients to document the date, time, and duration of each light treatment. Light therapy should continue until symptom remission. Research suggests continuing light exposure through the entire duration of the symptomatic months ( Lam & Tam, 2009). To learn more about light therapy, consider reading A Clinician’s Guide to Using Light Therapy, Chronotherapeutics for Affective Disorders: A Clinician’s Manual for Light and Wake Therapy, and Winter Blues. To learn more about seasonal affective disorder, consider reading Seasonal Affective Disorder: Practice and Research.