Frandsen_Pareek_Hansen_2014

The study was a randomised, single-centre, doubleblind, placebo-controlled trial including healthcare professionals employed in psychiatric and somatic hospitals. The participants were suffering from moderate seasonality with SAD symptoms.

Participants of the study are healthcare workers from various psychiatric and regular hospitals who have seasonal affective disorder (SAD). Participants were randomly selected to be part of a control group (given a placebo) and a treatment group (given a vitamin D supplement).  Neither the participants nor the people doing the study know who is getting a placebo or who is getting a supplement in order to test the efficacy of vitamin D supplementation on treating SAD.

Indoor work has been hypothesized as a risk factor for mood difficulties among civil servants in a Danish crosssectional study (latitude 55-57N°), a significant risk reduction (odds ratio = 0.63) being found in outdoor workers (>2 hours/day). Thus, indoor work might be a significant risk factor for SAD, since indoor work is by far the most prevalent form of work among the total work force at temperate latitudes

People who work indoors in Denmark were researched in another study and were found to be at a higher risk of developing mood disorders.  Thus, people who work indoors, which is common in temperate locations like Denmark, Canada, and the USA, are believed to be at a greater risk of developing SAD.

Of the 43 participants randomised, 22 received 70 μg of active vitamin D, and 21 received placebo. 34 completed the study, and data were collected for the primary, secondary and exploratory outcomes during winter-spring (January, February, March 2012)

A total of 43 people participated in the study, with 22 of them receiving a vitamin D supplement and 21 of them receiving a placebo.  Only 34 of those 43 people got through the entire study.    The primary outcome is the participant’s responses on questionnaires about mood and depression levels.  The secondary outcome is the participants responses on questionnaires about their well-being. The exploratory outcome was information collected about a participant’s weight, waist circumference, blood pressure, and absenteeism from work.  This information was collected by researchers during January, February, and March of 2012.

[T]he overall most significant finding in this study was that vitamin D had no effect on SAD symptoms.

The study data, once analyzed by the researchers, indicated there was no measurable improvement in mood or symptoms between the placebo group and the treatment group.  There is no indication according to this study that vitamin D supplementation can help people who suffer from SAD.

This study was limited to the later winter months after the winter solstice (January to March 2012) when the amount of sunlight during the day is increasing.  This could lessen the severity of the symptoms of SAD and cause participants to underreport the severity of the disorder on their mood.  A possible future direction could be the lengthening of the data gathering period from October to March (inclusive) to research whether the severity of SAD symptoms, and the possible alleviation of those symptoms could be affected by the length of available daylight pre- and post-winter solstice.

There was a lot of confusing acronyms strewn about the paper, like: SPAQ-SAD, CRP, PTH, WHO-5.  There was a handy abbreviation chart at the end of the paper that explained what the acronyms letters meant, but I only found it at the end after reading the entire paper which wasn’t helpful to make sense of all the jargon.  Even then, I feel like some of the abbreviations on that list were referencing questionnaire formats that I’m unfamiliar with, so I’m unsure how rigorous the methods used in this study are at assessing SAD.

I did see a lot of issues with this study and its generalizability to SAD and vitamin D supplementation.  For one, the study was extremely small, with only 34 participants.  And despite the study explaining that SAD seems to affect females more than males, there is no breakout of the data looking at that trend, nor any discussion on the number of women or men who even participated.  The study also gathered its participants from people who volunteered, so this may not be a reliable way to people who have significant, severe SAD, versus people who may be self-diagnosing and may not meet clinical standards for disorder diagnosis.  The study also excluded people who have significantly depleted serum vitamin D levels and may benefit the most from supplementation affecting the symptoms of SAD.  And as I discussed above, the study was extremely limited in duration and involved a period where the most severe effects of SAD would be expected to naturally start to resolve, as the amount of daylight starts to increase after the winter solstice.