Brain MRI white matter hyperintensities and one-carbon cycle metabolism in non-geriatric outpatients with major depressive disorder (Part II)

The objective of this study was to investigate the relative impact of brain white matter hyperintensities (WMHs), cardiovascular risk factors and elements of the one-carbon cycle metabolism (including serum folate, vitamin B12 and homocysteine levels) on the outcome of antidepressant treatment in non-elderly subjects with major depressive disorder (MDD). Fifty MDD subjects were administered brain magnetic resonance imaging (MRI) scans at 1.5 T to detect T2 WMHs. The severity of brain WMHs was classified with the Fazekas scale (range = 0-3). We assessed cardiovascular risk factors in all MDD subjects (age, gender, smoking, diabetes, family history, hypertension, cholesterol). MDD patients also had serum folate, vitamin B12 and homocysteine levels measured. All MDD subjects received treatment with fluoxetine 20 mg/day for 8 weeks. In a logistic regression, the severity of subcortical WMHs and the presence of hypofolatemia were independent predictors of lack of clinical response to antidepressant treatment. Separately, hypofolatemia also predicted lack of remission to antidepressant treatment. These associations were independent of the presence of smoking, diabetes, family history, hypercholesterolemia, hyperhomocysteinemia and low B12 levels. Although preliminary, the results of the present work suggest that subcortical brain WMHs and hypofolatemia may have an independent negative impact on the likelihood of responding to antidepressant treatment in non-geriatric subjects with MDD.