MedicalResearch.com Interview with:
Prof. Steven LoBello, Professor of Psychology
Auburn University at Montgomery
Study co-authors: Megan Traffanstedt (graduate student) and Dr. Sheila Mehta
Medical Research: What is the background for this study? What are the main findings?
Response: Looking at a large sample of the U.S. population who completed the PHQ-8 depression scale we found that there is no relation between different seasons and prevalence of depression. Sunlight exposure is supposed to be the key variable at work here, so we also obtained sunlight data from the US Naval Observatory about sunlight exposure time in the communities of survey respondents on the date of their interviews. We found no relationship between amount of available sunlight and prevalence of depression. Finally we also evaluated prevalence of depression in 3 different latitude bands, latitude being an often-used proxy for sunlight exposure. Again, we found no relationship between prevalence and latitude of residence. Our findings pertain to the DSM 5 diagnostic category of major depression with seasonal variation.
Medical Research: What should clinicians and patients take away from your report?
Response: People commonly experience “bad moods” and certainly these can occur in winter and any other time. People may also experience major depression in winter or any other time of the year. Neither event may be freely interpreted as being caused by light deprivation. If we are looking for treatments that address actual causes of major depression, I would be less inclined to look toward those that address the effects of diminished sunlight exposure.
Medical Research: What recommendations do you have for future research as a result of this study?
Response: We want to check our results with other data sets to see if the findings converge. In the article, we hypothesize that this belief in seasonal depression may be the result of certain folk beliefs about how natural phenomena may affect health and disease susceptibility. We hope to design experiments to test this hypothesis.
Finally, because people with depression are quite likely to experience relapse, we want to model the recurrence of depression, which may be done using simulation techniques, and investigate the recurrence pattern of depression across seasons and under different assumptions.
K. Traffanstedt, S. Mehta, S. G. LoBello. Major Depression With Seasonal Variation: Is It a Valid Construct?
Clinical Psychological Science, 2016; DOI: 10.1177/2167702615615867
Prof. Steven LoBello, Professor of Psychology (2016). SAD? No Relationship Between Sunlight and Depression