Depression is a highly prevalent form of mental illness, and affects approximately 350 million individuals worldwide. Those who experience depression are commonly overwhelmed by feelings of negativity, sadness or disinterest in activities once enjoyed. Changes in appetite and sleeping patterns, fatigue, difficulty concentrating and feelings of worthlessness are all common symptoms of depression.
There are many factors that may contribute to the onset of depression, including genetic predisposition, stressful or traumatic life events, chronic pain or illness and the use of some medications. Additionally, depression is much more common among young adults, women and the elderly.
Past research has discovered a relationship between vitamin D status and depression, though the findings have been conflicting. However, recent studies suggest vitamin D status is linked with depression in pregnant women, lactating women, adolescents and the elderly. Due to the increased risk of vitamin D deficiency in older age, researchers decided to further evaluate the relationship between vitamin D deficiency and depression in an elderly population.
Researchers included a total of 5,870 participants from the ELSA study, a community-based prospective study based in England. All participants were over the age of 50 years and had available vitamin D levels. Additionally, each individual underwent a test to measure depressive symptoms. Researchers used the Center for Epidemiological Studies – Depression (CES-D) Scale to determine depression severity, with lower scores indicating more severe feelings of depression. Medical, demographic and socioeconomic data were recorded from all participants and used in the multivariate analysis.
This is what the researchers found:
- The participant’s average vitamin D status was 19.5 ng/ml (48.7 nmol/l).
- Vitamin D levels below 20 ng/ml (50 nmol/l) were associated with a 1.71 increased odds of experiencing depressive symptoms (95% CI: 1.44-2.03).
- Vitamin D levels between 12-20 ng ml (30-50 nmol/l) were associated with a 1.35 increased odds of experiencing depressive symptoms (95% CI: 1.10-1.64).
- Vitamin D levels below 12 ng/ml (30 nmol/l) were associated with a 2.26 increased odds of experiencing depressive symptoms (95% CI: 1.89-3.04).
- For female participants, 25(OH)D levels less than 12 ng/ml (30 nmol/l), below 20 ng/ml (50 nmol/l) and between 12-20 ng/ml (30–50 nmol/l) were associated with a 1.92, 1.61 and 1.38 increased chance of experiencing depressive symptoms, respectively (95% CI = 1.50–2.47, 95% CI = 1.07–1.77, 95% CI = 1.30–2.00)
- For men, this association was only significant for vitamin D levels less than 12 ng/ml (30 nmol/l) (95% CI = 1.06–2.42).
The researchers concluded:
“In summary, our study suggests a potential role of 25OHD in depression, especially among women. Our findings, therefore, contribute significantly to the body of evidence supporting a role for vitamin D in depression.”
This study had several strengths that should be acknowledged. First, the number of participants with available vitamin D levels was one of the largest to date in England. Additionally, the large number of cofounders that the researchers adjusted for created a more clear association between vitamin D status and depression in this population.
However, this study was limited by its cross sectional study design, which does not allow researchers to determine if a causal relationship exists between vitamin D and depression.
Further randomized controlled trials are needed to determine if there is a causal relationship between vitamin D status and depression in an elderly population.
Peterson, R. & Cannell, JJ. Vitamin D status is associated with risk of depression in later life, especially in elderly women. The Vitamin D Council Blog & Newsletter, 2017.
de Oliveira, C. et al. Associations Between Vitamin D Levels and Depressive Symptoms in Later Life: Evidence From the English Longitudinal Study of Ageing (ELSA). The Gerontological Society of America, 2017.