Seasonal affective disorder (SAD) presents a unique opportunity in psychiatric prescribing because, unlike many other mood disorders, the timing of symptoms is often predictable. Patients typically experience depressive symptoms during the fall and winter months, with improvement in the spring and summer. Seasonal affective disorder is classified as a seasonal pattern of Major Depressive Disorder or, in some cases, Bipolar Disorder, which becomes especially important when choosing pharmacologic therapy. In this article, we will discuss the use of antidepressants in seasonal affective disorder.

SSRIs for SAD

Among pharmacologic options, selective serotonin reuptake inhibitors (SSRIs) are the most commonly used and best-studied class. Agents like Sertraline, Fluoxetine, and Escitalopram are frequently chosen because of their strong evidence base in depression overall, their favorable tolerability, and their effectiveness in treating coexisting anxiety symptoms, which are common in seasonal depression. In practice, SSRIs are typically started when symptoms emerge in the fall and continued throughout the symptomatic season.

Bupropion

Bupropion has been specifically studied and approved for the prevention of seasonal depressive episodes. Its mechanism, which involves norepinephrine and dopamine, makes it especially useful for symptoms like low energy, fatigue, hypersomnia, and decreased motivation—features that are often prominent in seasonal affective disorder. For patients with a clear, predictable pattern of recurrence, bupropion can be started proactively in early fall before symptoms begin, rather than waiting for symptoms to develop.

Choosing an Antidepressant in SAD

SSRIs

• Use for most patients
• Sertraline and fluoxetine have significant evidence to support their use
• Strongly preferred over bupropion in patients who have a significant anxiety component

Bupropion

• Activating in nature, so it may be most helpful in hypersomnolence
  • Avoid in patients with significant insomnia
• Strong consideration for patients who gain weight during the fall/winter months
• Avoid in seizure disorder

Bipolar Disorder

Special consideration is needed for patients with Bipolar Disorder. In these cases, antidepressant monotherapy should generally be avoided due to the risk of inducing mania. Instead, treatment typically involves mood stabilizers or atypical antipsychotics, with antidepressants used cautiously and usually in combination with a mood-stabilizing agent.

Tapering Antidepressants in Seasonal Affective Disorder

Tapering antidepressants in seasonal affective disorder is reasonable. When symptoms have remitted and the patient is entering a low-risk season, a gradual dose reduction over several weeks is typically appropriate. A common approach is to decrease the dose by 25 to 50 percent every two to four weeks, with adjustments based on the specific medication, duration of use, and patient history. Slower tapers are often warranted for patients who have been on long-term therapy, are taking higher doses, or have previously experienced discontinuation symptoms. During the taper, it is important to monitor for both recurrence of depressive symptoms and withdrawal effects, particularly with SSRIs that have shorter half-lives. Reminder that fluoxetine has one of the longest half-lives and may be easier to taper (excellent board exam nugget)

Not all patients with seasonal affective disorder should discontinue medication in the spring. Some individuals have a more complex pattern with non-seasonal depressive episodes or a history of frequent relapse, in which case continuing treatment year-round may be more appropriate. This highlights the importance of recognizing that seasonal affective disorder exists on a spectrum rather than as a single uniform condition.