Dietary magnesium may protect against cognitive decline in women

Takeaway

• Postmenopausal women with a total magnesium intake between the estimated average requirement and recommended dietary allowances (257.3-317.8 mg/day) had reduced risks for mild cognitive impairment (MCI) alone and for the composite of MCI and probable dementia.

Why this matters

• Attractiveness of lifestyle modification to reduce risk.

Key results

• 11.8% of women developed MCI and/or probable dementia during >20 years of follow-up.
• In multivariate analysis, compared with quintile 1 of magnesium intake, risk for MCI alone significantly lower for:
  • Quintile 3 (HR, 0.63; 95% CI, 0.45-0.87).
  • Quintile 4 (HR, 0.67; 95% CI, 0.46-0.97).
  • Quintile 5 (HR, 0.61; 95% CI, 0.39-0.96).
• Risk for MCI/probable dementia significantly lower for quintile 3 (HR, 0.69; 95% CI, 0.53-0.91).
• No significant associations observed for probable dementia alone.

Study design

• Prospective cohort study of 6473 postmenopausal women aged 65-79 years without dementia (Women’s Health Initiative Memory Study).
• Main outcomes: physician-adjudicated MCI and/or probable dementia.
• Funding: National Heart, Lung, and Blood Institute, National Institutes of Health; US Department of Health and Human Services; Wyeth Pharmaceuticals; National Institute on Aging.

Limitations

• Magnesium intake assessed at baseline only.
• Lack of information on serum levels.
• Intake via standard multivitamins not assessed.
• Residual confounding.
• Unknown generalisability.