Seasonal affective disorder: When the weather affects mood

Approximately 5% of American adults experience seasonal affective disorder (SAD)—a form of depression seemingly triggered by the change of seasons—most often from summer to fall and winter, according to Cleveland Clinic.^[]

While the exact causes of SAD are unknown, research suggests various chronobiological and neurobiological factors play into its development. Therapies like light therapy and treatment with selective serotonin reuptake inhibitors (SSRIs) may positively influence SAD’s progression, but other treatments, including cognitive behavioral therapy (CBT), also have demonstrated effectiveness.

Contributors to SAD

Severe SAD symptoms pose a significant impedance to the patient’s quality of life. SAD symptoms mimic those found in people with major depressive disorder (MDD) and often include anxiety, ongoing depression, feelings of agitation or irritation, and loss of interest in previously pleasurable activities, as per Cleveland Clinic.

Thoughts of suicide or death are common in extreme SAD cases. Individuals diagnosed with SAD may also experience carbohydrate cravings, extreme fatigue, and hypersomnia.

A study published in BMC Psychiatry in 2021 suggested that geographical location is a common risk factor for SAD.^[] The researchers found that individuals living in more northern latitudes with shorter periods of daylight in the fall and winter were at an almost 10% higher risk for SAD compared with those closer to the equator.

Other factors like vitamin D deficiency, family history of SAD, and personal history of other psychiatric conditions, such as bipolar disorder or MDD, seem to heighten a patient’s risk for SAD, according to the Mayo Clinic.^[] The condition also seems to affect younger people and biological females more often.

Treatment challenges

For psychologists, treating the disorder may present a significant challenge. Key practices recommended in an article published by American Family Physician included light therapy and CBT as first-line interventions.^[]

According to the research, both of these treatments significantly improve depression severity; additionally, CBT was found to lower the recurrence of symptoms, suggesting it is superior to light therapy among study groups.

SSRIs such as fluoxetine and sertraline can be helpful for some patients, but there is very little research on the use of antidepressants in SAD and others may not benefit from such treatment, as reported in American Family Physician.

Clinicians should therefore tailor treatment plans to fit each patient’s specific needs; a one-size-fits-all approach to treating SAD is not an effective strategy for improving rates of seasonal depression among patient groups.

Preventative measures

Less well-understood is the efficacy of preventative efforts intended to stave off symptoms or even totally prevent syndrome recurrence.

According to a study published in BMC Psychiatry that included interviews of 10 patients and five physicians, preventative therapies can be effective if a patient has a better understanding of the mechanisms of SAD, including its high recurrence rate.^[]

All but one patient reported using preventative measures—such as spending more time outside, getting regular exercise, and eating a nutritious diet—as reasonable options.

Additional research cited in the 2018 BMC Psychiatry article suggested that using the antidepressant bupropion (Wellbutrin) as a preventative measure may dramatically lessen a patient’s likelihood of recurrence. A systematic review found that bupropion extended-release tablets were 44% more effective at preventing new depressive episodes compared to placebo.

Other research in the American Family Physician article indicated that starting bupropion between September and November of each year may reduce rates of MDD episodes during the fall and winter months. Bupropion extended-release is the only pharmaceutical product with an FDA indication for SAD prevention.

Clinicians should consider implementing preventative measures whenever possible while providing a wide range of treatment options that fulfill the unique needs of individual patients.