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Three Seasonal Depression Myths

Part 9: Identifying and understanding major depression subtypes.

Key points

  • Seasonal major depressive episodes are four times more prevalent in women.
  • Decreased or increased sunlight can spur seasonal depression.
  • Treatment includes light therapy, anti-depressants, exercise, and psychotherapy.
Source: Qimono/Pixabay

Anyone who has endured a long, cold winter has probably encountered a touch of the winter blues. This is a relatively normal experience whereby we might become lethargic, carb-craving, and a little moody. It tends not to be what psychology professionals term "pervasive," meaning it doesn't significantly affect our ability to function well. Those sidelined by depression in the winter are usually referred to as having seasonal affective disorder, but this is one of the misunderstandings about seasonal moods.

Three Misunderstandings About Seasonal Affective Conditions

  1. Significant winter depression is termed seasonal affective disorder. This, however, is not an actual diagnosis but rather a pop-cultural term for seasonally-occurring depression. The correct diagnostic term is major depressive disorder (MDD) with seasonal pattern. It is essential to note the MDD, signifying it is a serious depressive event.
  2. Winter is the only season correlated to depression. While winter is the season popularly equated with the development of mood pathology, note that the specifier is with seasonal pattern, not specifically winter onset. Interestingly, a subset of people with seasonal pattern become depressed in the brighter months (e.g., Mondimore, 2006; DSM-5).
  3. Depression is the only mood associated with seasonal patterns. Seasonal affective changes are popularly thought of as a depressive phenomenon. However, bipolar disorder patients can become hy/manic with the seasons (e.g., Wang & Chen, 2013; Medici et al., 2016), noted as far back as Hippocrates. Some researchers (e.g., Grierson et al., 2016; Takaseu, 2018) have noted a significant correlation between bipolar disorder episodes and circadian rhythm, affected by the seasons.

What Might Cause Seasonal Depressive Shifts?

The most common manifestation of MDD with seasonal pattern is indeed correlated with shortening days. This presentation is up to four times more prevalent in females and increases the further people live from the equator (Melrose, 2015). One theory that has been extensively researched is that it's influenced by lack of vitamin D, which sunlight naturally provides, and is well-known to be correlated with healthy moods (e.g., Parker et al., 2017; Vellekkatt et al., 2018).

Fleshing out this theory, it appears that a significant role of vitamin D is regulating serotonin transporters, particularly one called "sert." People prone to Seasonal Onset moods seem prone to vitamin D sensitivities, most likely a genetic nuance (Stewart et al., 2014). Patients who have a pattern of developing an MDD episode as the days shorten tend to have an overabundance of sert (e.g., Ruhe et al., 2011; McMahon, 2016).

Thought of another way, the lack of sunlight leads to vitamin D deficiency. Vitamin D is needed as a bouncer, allowing only the correct percentage of sert to the party. If too much sert is on the scene, serotonin is then just being ushered through, not being allowed to have much of an effect on mood regulation. It is no secret that minimal serotonin saturation is highly correlated with depression.

Conversely, it stands to reason that the individuals who develop MDD in correlation to increasing sunlight may have too much sert regulation. This bouncer is stingy and won't admit enough to the party. The brain is again not being saturated with serotonin, but now it is because there aren't enough escorts to deliver all needed.

Another theory as to the vitamins' role in mood is noted by researchers Ceolin et al. (2021): "Vitamin D also presents a relevant link with chronobiological interplay, which could influence the development of depressive symptoms when unbalance between light-dark cycles occurs."

The Presentation

Of note, Seasonal Pattern MDD seems correlated to the Atypical Features presentation (e.g., Mondimore, 2006; Harvard, 2014; Wirz-Justice et al., 2019). What is most noteworthy, though, is when it makes its appearance. First, however, it is essential to realize that the seasonal shifts aren't the only time patients with seasonal pattern may get depressed; they could have a general ebbing and flowing of episodes. However, like clockwork, as the sunlight changes, they indeed settle into an MDD episode each year.

For someone to have established a seasonal pattern, it is noted in diagnostic criteria that there must be at least two consecutive instances of seasonal onset with complete remission as the season changes. There is no seasonal demarcation indicating what's too little or too much sunlight, meaning it doesn't simply happen at the extremes, closest to solstices. Autumn's case helps illustrate:

Autumn, a 30-year-old professional, met with Dr. H after noticing a significant downward spiral as the fall progressed. She reported that she felt blue off and on for several years in the winter, but if she took occasional trips down south to see her parents and kept busy, she muddled through it and was good until the following winter.

This time, the blue feeling started in September, and she slowly found herself overeating and fatigued on top of the blueness, which was quickly turning to gray as she headed into November. She said,

As the day wears on at work I feel a brain fog and all I want to do is get home after work and hunker down to a movie, but I usually fall asleep halfway though The other day at work I was moving slower and slower, and my colleague told me I didn't look good. If other people are seeing it, I figured I better call someone!

Autumn's experience is not unusual. If we ask MDD seasonal pattern patients to think about when first symptoms surfaced, we may see the seasonal pattern was a months-long, insidious process until they met MDD criteria. Depending on the person's sensitivity, their mood could begin changing in the late summer as days are noticeably shortening.

I've met others who don't get depressed until we only have ten hours or less sunlight. Untreated symptoms may remit as soon as days begin lengthening or take well into spring.

Source: Cottonbro/Pexels

Treatment Implications

I've told patients with seasonal onset that, in a way, if you're going to get major depression, this is the one to get because you know what to expect and can prepare for it. This is especially true if it is the only time they experience depression.

Patients who struggle with depression throughout the year should be doing much of what follows already, but we may need to help them increase the activity if they are prone to seasonal pattern. In therapy, we can reflect on the impending seasonal pattern and help them assemble their minimal daylight survival kits:

  • Many choose to discontinue their antidepressant after the seasonal depression ends. If so, arranging a visit with their psychiatrist at least a month before the normal onset of depression symptoms is essential. This will allow the medication time to take effect ahead of the curve.
  • Vitamin D lamps have been met with some success by many. Encourage patients to discuss this with their psychiatrist.
  • It is no secret that exercise has a significant effect on mood. If they aren't exercisers in general, develop a physical activity plan (after consultation with their physician, of course). If they already do exercise, perhaps increasing the number of days going to the gym or getting a gym partner to keep them motivated will be necessary.
  • Winter depression is correlated with increased appetite, especially carb cravings, which can add weight and further moodiness from sugar spikes and crashes. Review the importance of the effect of diet on mood, and encourage a visit with a nutritionist to help patients maximize a diet conducive to bettering mood. Diets high in Vitamins E and D, folate, and lean protein are well-researched as medical foods for fighting depression, especially with antidepressant medications.
  • Finding increased structure at a time of year that even non-depressed people tend to hibernate. This could be engaging in volunteer work, making it more of a point to engage in hobbies, or arranging regular social outings. Clients have found it helpful, for example, to be held to having coffee each day after work with a different family member or friend and lunch every Sunday with their siblings at a different restaurant.
  • All along, the good therapist will be a supportive taskmaster for the above, along with helping their patients manage the inherent day-to-day struggles. This may be cognitive-behavioral approaches to improving motivation, managing relationships that could become wrinkled due to their depressed state (especially sexual, given libido can decline with depression and be further reduced by some antidepressants), and managing the low self-esteem, and dark thoughts that ebb and flow with depressed states.

Remember, the needs of each patient are different, so it's essential to review progress and what they feel they require. Not everyone needs weekly therapy during seasonal depression. Thankfully, many do well with medication, diet, and exercise and only require a seasonal check-in to prepare.

To find a therapist, visit the Psychology Today Therapy Directory.


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