Lack of Vitamin D associated with greater risk of depression

Older adults with Vitamin D deficiency are at greater risk of developing depression, finds a study.

The study has been published in Journal of Post-Acute and Long-Term Care Medicine (JAMDA).

A new study by researchers from The Irish Longitudinal Study on Ageing (TILDA) at Trinity College Dublin has shown for the first time in Ireland that a deficiency in vitamin D was associated with a substantial increased risk of depression (+75 percent) over a four-year follow up period.

Later life depression can significantly reduce quality of life and is a potent risk factor for functional decline, admission to residential care and early death. Given the complex nature of depression, including the fact that the majority of older adults are undiagnosed, prevention is a priority and the identification of important risk factors is crucial.

Vitamin D or the 'sunshine vitamin' is essential for bone health and deficiency, and has recently been linked with other non-bone health outcomes such as inflammation and diabetes. Small studies have found links between vitamin D and depression but few have followed up with the same affected people over time, while others have not taken into account other factors that can also affect depression. These findings are important as the TILDA team has previously reported that 1 in 8 older Irish adults are deficient in vitamin D.

The current study investigated the links between vitamin D and depression in older Irish adults and then re-examined the participants four years later to see if vitamin D status affected the risk of developing depression.

The authors found that:

-Vitamin D deficiency was associated with a 75 percent increase in the risk of developing depression by 4 years

-This finding remained robust after controlling for a wide range of relevant factors including depressive symptoms, chronic disease burden, physical activity and cardiovascular disease

-Furthermore, excluding participants taking anti-depressant medication and vitamin D supplementation from the analyses did not alter the findings

-The authors suggest that the findings could be due to the potential direct effect of vitamin D on the brain. Given the structural and functional brain changes seen in late life depression, vitamin D may have a protective effect in attenuating these changes. Similarly, other studies have shown that vitamin D status has also been linked with neurodegenerative conditions such as dementia, Parkinson's disease and Multiple Sclerosis.