A longitudinal Dutch study published in the latest edition of the Archives of General Psychiatry has confirmed that low levels of vitamin D and high levels of parathyroid hormone are linked to depression in older people.

The association has been suspected for some time but the study’s author say the connection “has never been studied systematically”.

Data for the findings was gathered as part of a long-term ageing study in Amsterdam with over 1,200 participants between the ages of 65 and 85. 

The team of researchers conducted diagnostic interviews and used self-reporting methods to gauge the levels of depression among the group and matched them with vitamin D and parathyroid hormone levels.

They found that vitamin D levels among 169 participants with minor depression and 26 participants with a major depressive disorder were 14 per cent lower than in the control group.

Parathyroid hormone levels were five per cent higher among participants with minor depression and 33 per cent higher among the severely depressed group.

The report did not determine whether the abnormal levels of vitamin D and parathyroid hormone are a cause or a symptom of depression.

But if vitamin D is a cause of depression, the researchers suggest supplementation and exposure to sunlight could help to improve mood.