Does Winter Really Have an Effect on Symptoms of Depression?

There are many who have heard of the term “seasonal depression”, or who have had their low mood being attributed to “winter blues”. This phenomenon is understood by the general public to mean a higher tendency to feel depressed during a specific season, typically winter. Within the field of psychology, this has been coined “Seasonal Affective Disorder”, and is described as recurrent depressive episodes that occur with changes in the season for at least 2 consecutive years. However, Seasonal Affective Disorder (SAD) is not recognized as a disorder in the Diagnostic and Statistical Manual of Mental Disorders. Instead, major depressive disorder can be assigned “with seasonable pattern”, if the seasonal episodes substantially outnumber non-seasonal ones for two years.

One of the main reasons why SAD hasn’t been officially recognized by the DSM is because most research on the SAD uses the Seasonal Pattern Assessment Questionnaire as a diagnostic measure, which asks the participant to use retrospection to document perceived mood changes through the seasons. Participants typically overestimate their symptoms, and the subjective nature of this measure is not in line with DSM criteria. In addition, two studies from USA and Norway failed to provide evidence of SAD, which led to SAD being considered “a folk psychological construct”.

The current study aims to measure SAD with the Canadian Community Health Survey, which collects data over the span of a year. This survey asks participants to recount their experiences over the past two weeks, omitting the issue of long-term recall of symptoms. The Canadian Community Health Survey uses the PHQ-9 as a measure of depressive symptoms, which is a nine-item scale that can either be interpreted as an ordinal symptom rating, or as a cut-point. This means that the scores are categorized into different groups according to how intense their symptoms are. The Canadian Community Health Survey includes residents above the age of 12 living in Ontario, Manitoba, Saskatchewan, New Brunswick, Newfoundland and Labrador, The Northwest Territories, Nova Scotia, and Prince Edward Island.

As expected and supported by other studies, the results of the study showed higher self-rated depression symptoms in females, those with a chronic condition, binge drinkers, those in the lowest income groups, and those who were separated, widowed, or divorced. In addition, the study uncovered an interaction between age and seasonal depressional symptoms. The younger group (age 12 - 24) were more likely to report feelings of seasonal depression, as opposed to the older group (age 25+). Results were further stratified by student status, but the results showed that the likelihood of experiencing seasonal depression did not differ between students and non-students.

An analysis of the results show that the ratings of major depressive episodes do not increase or decrease depending on the season. This can possibly be due to the number of respondents diagnosed with depression being small, or it can simply mean that season has little to no effect on major depressive episodes. On the other hand, seasonal variability does have an effect on experiences of mild symptoms, as it is more likely to experience these during the winter. A possible cause of the mixed results in previous studies was also explored – it is possible that previous studies didn’t look into the variability between different age groups, explaining why some studies didn’t find any evidence of seasonal depression while others did. The larger sample used in this study may also explain the slight variation in results. It is also possible that the harsher winters in Canada lead to a more prevalent experience of depressional symptoms, as compared to the countries where the previous studies took place.

In conclusion, while the seasons can not be solely blamed for experiencing symptoms of depression, it is a factor that should be taken into consideration. It is also important to further study the effect of psychosocial differences between the seasons – vacations tend to be in the summer, school-related stress tends to be in the winter, etc. There is a greater risk of experiencing these symptoms in the winter as opposed to other seasons. As such, it might be effective for mental healthcare practitioners to consider this when dealing with patients and their recovery, such as using light therapy as a treatment.

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Source:

• Lukmanji, A., Williams J., Bulloch, A., Bhattarai, A., Patten, S.B. (2019). Seasonal variation in symptoms of depression: A Canadian Population Based study. Journal of Affective Disorders, 255. doi: https://doi.org/10.1016/j.jad.2019.05.040