Folic acid combined with DHA supplementation improves cognitive function in older adults with MCI Original paper

Mild cognitive impairment (MCI), an intermediate state between normal brain function and dementia, is considered to be a precursor to Alzheimer’s disease (AD). Previous studies have suggested that both folic acid and the omega−3 fat docosahexaenoic acid (DHA) may benefit cognitive function in patients with MCI. Although the mechanisms that cause dementia are not well understood, there may be links to increased amyloid-β (Aβ) levels. Although both DHA and folic acid have been shown to individually reduce Aβ levels in cell and animal studies, this hasn’t been thoroughly tested in humans.

In a 6-month randomized controlled trial, 138 patients (>60 years of age) with MCI were randomized into four different intervention groups: folic acid (0.8 mg/day) + DHA (800 mg/day), folic acid alone (0.8 mg/ day), DHA alone (800 mg/ day), or a placebo. Cognitive function (as assessed by a battery of tests) and amyloid-β levels in the blood were measured at baseline and after the 6-month intervention. Cognitive function was also assessed at a 12-month follow-up (6 months postintervention) to determine whether any improvements in cognitive function caused by the intervention were maintained.

Folic acid alone improved the full-scale intelligence quotient (FSIQ), arithmetic, and picture complement scores. In the DHA-alone group, the FSIQ and information, arithmetic, and digit span scores improved. Folic acid + DHA improved arithmetic and digital span scores. At the 12-month follow-up, most measures of cognitive function declined relative to those measured immediately postintervention. DHA lowered levels of the 40-amino-acid Aβ40 peptide (Aβ40), while folic acid + DHA reduced Aβ42 and Aβ40 levels more than DHA alone. These results indicate that 6 months of combined folic acid and DHA supplementation can improve cognitive function in older adults with MCI, but the improvements in cognition may not be maintained after stopping supplementation.