Vitamin B₁₂, homocysteine and depressive symptoms: a longitudinal study among older adults

The roles of vitamin B₁₂ and homocysteine concentration in depression are not clear. We investigated cross-sectional and prospective associations of serum vitamin B₁₂ and plasma homocysteine with depressive symptoms in Dutch older adults.

In the Longitudinal Aging Study Amsterdam (LASA), blood was collected in 1995/1996 among 1352 men and women aged ⩾65 years. Depressive symptoms were assessed with the Center for Epidemiologic Studies Depression Scale (CES-D) six times from 1995/1996 to 2011/2012. Multiple linear regression and mixed models were used to assess whether vitamin B₁₂ and homocysteine were associated with severity at baseline and course of depressive symptoms over 16 years. Cox regression analyses were performed for the associations with incidence of depression (CES-D ⩾16 and/or antidepressant use). All analyses were adjusted for sociodemographic characteristics and lifestyle factors.

Vitamin B₁₂ was neither cross-sectionally (n=1205) nor prospectively (n=1012) associated with depressive symptoms (adjusted β for CES-D over time, lowest versus highest quartile: -0.04 (95% confidence interval (CI): -0.15-0.06)). We also found no association with incident depression (n=853), except for a higher risk of depression over time in younger participants (aged 64.8-73.4 years; continuous vitamin B12, adjusted hazard ratio per s.d.: 1.38 (95% CI: 1.10-1.72)). For homocysteine, no associations were found, except for a lower risk of depression in younger participants.

Our study did not confirm earlier shown associations of serum vitamin B₁₂ and plasma homocysteine with severity and course of depressive symptoms and incidence of depression in older adults. Further research into the influence of homocysteine metabolism on mental health is needed.