Seasonal affective disorder (SAD) is a type of depression that occurs during certain seasons, usually winter, and affects millions of people around the world. People with SAD experience symptoms such as low mood, fatigue, disrupted sleep, loss of interest, and changes in appetite/weight. The causes of SAD are not fully understood, but some factors that may contribute to it are lack of sunlight, disrupted circadian rhythms, reduced vitamin D, and increased isolation. There are various treatments available for SAD, such as light therapy, medication, and lifestyle changes, but they may not work for everyone or have unwanted side effects. A newer and effective treatment option for SAD is transcranial magnetic stimulation (TMS), which uses powerful magnetic fields to stimulate specific areas of the brain involved in depression. This article will explore how TMS can help people with SAD cope with their symptoms and improve their quality of life.

Seasonal Affective Disorder

Seasonal Affective Disorder (SAD) is a prevalent mood disorder characterized by recurrent episodes of depression that occur at specific times of the year, typically during the fall and winter months when daylight hours are shorter. This condition, often referred to as “winter depression” or “winter blues” when mild, affects millions of people worldwide, with a higher prevalence in regions farther from the equator, where daylight duration varies significantly throughout the year. Symptoms tend to manifest and remit in a regular pattern, with the onset typically occurring in late fall or early winter and remission in the spring or early summer. Although less common, some individuals experience the reverse pattern, known as summer-onset SAD, with symptoms emerging in the warmer months.

The exact cause of SAD is not fully understood, but it is widely believed to be linked to disruptions in the body’s internal biological clock, known as the circadian rhythm, and alterations in neurotransmitter levels, particularly serotonin. Reduced exposure to natural sunlight during the fall and winter months can disrupt circadian rhythms, leading to a cascade of physiological and psychological effects. This includes changes in the production of melatonin, a hormone that regulates sleep-wake cycles, and serotonin, a neurotransmitter that plays a key role in mood regulation. These disruptions may contribute to the development of depressive symptoms in individuals susceptible to SAD.

The symptoms of SAD are similar to those of Major Depressive Disorder (MDD) and can vary in severity. Common symptoms include persistent low mood, loss of interest or pleasure in activities, fatigue, irritability, changes in appetite and weight, difficulty concentrating, and increased sleepiness. People with SAD may also experience physical symptoms like headaches, muscle aches, and oversensitivity to rejection. The severity of these symptoms can significantly impact a person’s daily functioning and quality of life.

Diagnosing SAD typically involves a thorough evaluation by a mental health professional. They will consider the pattern of symptoms over multiple seasons, ruling out other medical or psychiatric conditions, and may use standardized questionnaires to assess the severity of depression. Light therapy, or phototherapy, is a common and effective treatment for SAD. It involves exposure to bright artificial light that mimics natural sunlight and helps regulate the circadian rhythm. Light therapy is usually administered daily for a set duration, typically in the morning, and can lead to significant symptom improvement within a few weeks.

In addition to light therapy, other treatment options for SAD may include psychotherapy, particularly cognitive-behavioral therapy (CBT), which can help individuals develop coping strategies and address negative thought patterns associated with their depression. Medications such as selective serotonin reuptake inhibitors (SSRIs) may also be prescribed in more severe cases or when other treatments have not been effective.

Lifestyle modifications can complement medical treatments for SAD. These include maintaining a regular sleep schedule, engaging in regular physical activity, managing stress through relaxation techniques or mindfulness, and increasing exposure to natural daylight whenever possible, such as taking outdoor walks during the daytime.

Gender may affect the risk and severity of SAD and winter blues. Women are four times more likely to have SAD and winter blues than men, and they may also have different symptoms and responses to treatment.¹ Hormones, genes, and stress may explain this difference. Women with SAD and winter blues may crave more carbs and sweets, have more thyroid disorders, and experience greater mood variations attributed to dark and cloudy weather than men, which can affect symptom severity and overall quality of life.² Considering gender differences may inform treatment to better assess and address symptoms. It is essential for women to be aware of the signs and symptoms of SAD and winter blues, and to seek professional help if they feel overwhelmed or unable to cope. Likewise, it is important for men to be supported to overcome any barriers or stigma that may prevent them from acknowledging or addressing mental health challenges. Left untreated, SAD can lead to significant impairment in social, occupational, and academic functioning. By understanding the condition and its treatment options, individuals affected by SAD can better manage their symptoms and improve their overall well-being, enabling them to enjoy a more fulfilling life throughout the changing seasons.

TMS as a Promising Intervention

TMS may be an effective intervention for people suffering from SAD. TMS is a form of brain stimulation that applies powerful magnetic fields to specific areas of the brain involved in depression, such as the prefrontal cortex (PFC). The magnetic pulses induce electrical currents in the brain cells, which can affect their activity and connectivity. This can result in changes in brain chemistry, such as increased levels of neurotransmitters like serotonin and dopamine, which are associated with mood regulation and dysregulated in SAD.

Unlike medication, which affects the whole brain and body, TMS targets only the regions that need stimulation, reducing the risk of side effects. Unlike electroconvulsive therapy (ECT), which requires anesthesia and can cause memory loss, TMS does not induce seizures or impair cognition. TMS sessions are also shorter and less frequent than ECT sessions, making them more convenient and less disruptive for patients.

TMS and SAD

While several studies have shown the efficacy of TMS for Major Depressive Disorder, especially for those who do not respond well to other treatments, less research exists about SAD, a subtype of depression, specifically. Both high-frequency TMS (HFL-TMS) and low-frequency TMS (LFR-TMS) have shown promise in treating individuals with severe depression that is non-responsive medication.³ The US Food and Drug Administration has approved TMS as a treatment option for cases of depression that do not respond to other treatments and thus TMS may be suitable for SAD in some cases.

A possible benefit of TMS for people with SAD is that it can also help them cope with the winter blues and prevent relapse. The winter blues are a milder form of SAD that affect more people and cause less severe symptoms, such as feeling sluggish, melancholy, and unmotivated. The winter blues can still interfere with daily functioning and well-being, especially during the cold and dark months. TMS may help alleviate symptoms of SAD or the winter blues by stimulating the brain regions that regulate mood, energy, and motivation, such as the DLPFC and the ventral striatum. By enhancing the activity and connectivity of these regions, TMS can boost mood and motivation, to increase feelings of positivity and productivity. Moreover, TMS may also help prevent relapse of SAD and the winter blues by creating lasting changes in the brain, as has been the case in treatment-resistant depression.⁴ However, some people may need to maintain the benefits of TMS by following some strategies, such as regular follow-up sessions, booster treatments, and combining TMS with other therapies, such as cognitive-behavioral therapy (CBT) or mindfulness-based stress reduction (MBSR). These strategies can help reinforce the positive changes in the brain and provide additional support and skills for coping with SAD and the winter blues.

While the understanding and treatment of Seasonal Affective Disorder continue to evolve, TMS presents itself as a promising tool for individuals grappling with the winter blues. By targeting specific brain regions and providing lasting changes, TMS offers hope for those seeking relief from the seasonal challenges of depression, enabling them to regain control of their lives and embrace the changing seasons with improved mental well-being.

References

1. Jepson TL, Ernst ME, Kelley MW. Current perspectives on the management of seasonal affective disorder. J Am Pharm Assoc (Wash). 1999;39(6):822-829.
2. Lucht, M. J., & Kasper, S. (1999). Gender differences in seasonal affective disorder (SAD). Archives of Women’s Mental Health, 2(2), 83–89. https://doi.org/10.1007/s007370050040
3. Fitzgerald, P. B., Brown, T. L., Marston, N., Daskalakis, Z. J., Castella, A. d., & Kulkarni, J. (2003). Transcranial magnetic stimulation in the treatment of depression. Archives of General Psychiatry, 60(10), 1002. https://doi.org/10.1001/archpsyc.60.9.1002
4. Lan, M., Chhetry, B., Liston, C., Mann, J., & Dubin, M. (2016). Transcranial magnetic stimulation of left dorsolateral prefrontal cortex induces brain morphological changes in regions associated with a treatment resistant major depressive episode: an exploratory analysis. Brain Stimulation, 9(4), 577-583. https://doi.org/10.1016/j.brs.2016.02.011