Not Sad to See SAD Go

Wednesday, June 22, 2016

In a piece arguing for the idea that our brains may function more efficiently in the winter, Christian Jarrett notes that the whole idea of "Seasonal Affective Disorder" (SAD), a relatively new psychological diagnosis, has been cast into doubt:

The researchers, led by Professor Steven LoBello at Auburn University at Montgomery, asked their participants to complete a questionnaire about their depression symptoms over the previous two weeks. Crucially, the participants all completed the survey at different times of the year, allowing the researchers to look for any seasonal patterns.

Contrary to what you might think, the results provided no evidence whatsoever that people's depression symptoms tended to be higher in winter -- or at any other time of the year. This lack of a seasonal effect was true whether looking at the entire sample or only respondents with depressive symptoms. The respondents' geographical latitude and sunlight exposure on the day of the survey were also unrelated to depression scores.

The researchers are clear about what this means for what they call the "well-entrenched folk theory" that winter brings on or worsens depression. Their results, they write, "cast serious doubt on major depression with seasonal variation as a legitimate psychiatric disorder." They think the early studies on the concept of SAD were flawed by virtue of the fact that they selectively recruited people who said they suffered from winter-related mood changes -- an approach that was likely susceptible to confirmation bias, or selectively interpreting evidence to support a theory you already have. This makes intuitive sense. Once the concept of SAD was introduced, after all, it captured the public imagination and went on to spawn a whole industry based around ways to treat the "condition," including using artificial light. [bold added]
Jarrett goes on to make a quasi-plausible case for our brains functioning more efficiently in the winter, but I have no opinion on that one way or the other.

I don't expect sales of the above-mentioned lighting to decrease any time soon, and, who knows, perhaps they do good in some cases, due to a placebo effect. Or not. That said, I would be slow to mock someone who swears by them: Were I to venture a guess as to why such things might be helpful, it would be because of the fact the user was taking charge of something in his life in and of itself, more so than the individual action. This would particularly apply if he also did so in many other areas of his life and was at least trying his best to do the most rational thing.

-- CAV


Steve D said...

'Crucially, the participants all completed the survey at different times of the year, allowing the researchers to look for any seasonal patterns.'

I wonder the researchers randomized the season or date on which the participants took the survey for the first time or if there is an effect because of when they first took the survey?

In other words, there may be an effect due to taking the questionnaire multiple times which could mask any seasonal effect.

Gus Van Horn said...

Hah! That could be the case. Thanks for mentioning it.