Seasonal Depression

The term Seasonal Affective Disorder was first coined in 1984 by the National Institute of Mental Health.  Today, Seasonal Affective Disorder, also known as SAD, is an official diagnosis outlined in the Diagnostic and Statistical Manual of Mental Disorders. SAD is considered a subtype of depression that affects 4-6% of the U.S. populations and that happens during specific seasons of the year. While some cases occur in the spring and summer, known as Spring-Onset, the vast majority of cases occur during the fall and winter months, known as Fall-Onset.  

Researchers hypothesize that, “less sunlight and shorter days are thought to be linked to a chemical change in the brain.”  Specifically, with a shorter amount of daylight hours, the brain can increase the amount of melatonin it produces which may be linked to an increase in symptoms of depression.  Furthermore, people are generally more at risk for SAD the further they are from the equator, most likely because of the more severe changes in available daylight between seasons.  Women are also more likely to experience SAD than men, as they account for 4 out of every 5 cases. 

Additionally, researchers have potentially found a genetic mutation that may also be linked to SAD.  According to one genome-wide association study published in 2018, it was found that reduced mRNA expression of the gene ZBTB20 may be occurring in patients experiencing SAD. ZBTB20 is required for normal circadian rhythm, as studied in mice, thus, a reduced expression of it may play a factor in depression severity during seasonal changes. Furthermore, another study on the role of genetic factors suggests that there may be a, “familial contribution to the development of SAD,” and also found that, “two genetic variants related to serotonergic [nerve endings stimulated by serotonin] transmission… are associated with SAD.”        

Moreover, according to social worker Andrea Lawrence from UCHealth in Colorado, the severity of the COVID-19 pandemic may be exacerbating mental health struggles within the population, including a rise in SAD diagnoses. Lawrence states that, “symptoms of SAD and pandemic depression are cut from the same cloth.  Coupled together, those feelings are exacerbated.”  

In terms of treatment for Fall-Onset SAD, exposure to more sunlight is often extremely helpful.  In locations where daylight hours are in short supply, doctors recommend light therapy; there are even many affordable ‘sun lamps’ available for purchase for at home use.  In severe cases, patients can seek out psychotherapy and may even be prescribed antidepressants.  The most commonly used medications to treat SAD are SSRIs - selective serotonin reuptake inhibitors.  SSRIs are believed to be the most effective medication for SAD as they increase the amount of serotonin produced by the body which helps stimulate serotonergic transmission, as stated earlier. Additionally, some doctors recommend getting more vitamin D, as lower levels of it were linked to SAD in a 2014 study.  

As with most mental health disorders, doctors also recommend that those diagnosed with SAD try to get out and get active as much as possible during the day.  This is especially important during the pandemic, when patients may be stuck inside their homes without much access to natural daylight more so than ever before.

References: 

Ho, K, et al. “Genome-Wide Association Study of Seasonal Affective Disorder.” Translational Psychiatry, Nature Publishing Group UK, 14 Sept. 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC6138666/.

Orenstein, B. “12 Ways to Ease Seasonal Depression Symptoms: Everyday Health.” EverydayHealth.com, www.everydayhealth.com/depression/treatment/ways-to-ease-seasonal-depression/.

Overy, C, and E M Tansey. “The History of Modern Biomedicine.” The Recent History of Seasonal Affective Disorder (SAD) | The History of Modern Biomedicine, www.histmodbiomed.org/witsem/vol51.html.

Praschak-Rieder, N, and M Willeit. “Treatment of Seasonal Affective Disorders.” Dialogues in Clinical Neuroscience, Les Laboratoires Servier, Dec. 2003, www.ncbi.nlm.nih.gov/pmc/articles/PMC3181778/.

“Seasonal Affective Disorder (SAD).” Mental Health America, www.mhanational.org/conditions/seasonal-affective-disorder-sad.

“Seasonal Affective Disorder.” Johns Hopkins Medicine, www.hopkinsmedicine.org/health/conditions-and-diseases/seasonal-affective-disorder.

Sher, L, et al. “The Role of Genetic Factors in the Etiology of Seasonal Affective Disorder and Seasonality.” Journal of Affective Disorders, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/10404705/.

White, Mekialaya. COVID In Colorado: Fighting Seasonal Depression During The Pandemic. 13 Nov. 2020, denver.cbslocal.com/2020/11/13/covid-colorado-fighting-seasonal-depression-pandemic/.

Winthorst, W, et al. “Seasonal Affective Disorder and Non-Seasonal Affective Disorders: Results from the NESDA Study.” BJPsych Open, The Royal College of Psychiatrists, 30 Aug. 2017, www.ncbi.nlm.nih.gov/pmc/articles/PMC5572284/.