Mild Cognitive Impairment — supplement protocol
Mild cognitive impairment (MCI) is cognitive decline beyond what's expected for age and education, but not yet meeting dementia criteria. Roughly 10–20% of adults over 65 have MCI; conversion to dementia runs 5–15%/year. The single highest-value step is a specialist evaluation that screens for the substantial fraction of reversible causes (B12, thyroid, depression, sleep apnoea, medications, vascular contribution). Supplements have a real but modest adjunct role, mainly through correcting deficiencies and supporting vascular health. Several once-promising agents (ginkgo, vitamin E, low-dose lithium) have not held up in large outcome trials.
The supplement stack — modest evidence, real for some
Vitamin B12 — test and correct
Methylcobalamin 1000 mcg/day if B12 <400 pg/mL or MMA elevated; IM if absorption is impaired
B12 deficiency is a classical reversible-cognitive-decline cause and is under-diagnosed in older adults. Test serum B12 and methylmalonic acid (MMA — more sensitive marker). Treat to within the upper-normal range. PPI users, metformin users, vegans, and people with prior gastric surgery are at particular risk. Cognitive improvement from B12 repletion in true deficiency is real and well-documented.
Omega-3 (EPA/DHA) — DHA-emphasised
1–2 g EPA+DHA/day with food; choose DHA-emphasised products for brain
Higher DHA blood levels are associated with reduced dementia conversion in cohort data. The VITAL-MIND trial did not show overall cognitive benefit from omega-3 in healthy older adults, but observational and meta-analytic data favour DHA-emphasised supplementation in MCI — particularly in users with lower baseline fish intake. Modest effect; cardiovascular adjacency adds value.
Acetyl-L-Carnitine (ALCAR)
1500–2000 mg/day in divided doses
The Montgomery 2003 meta-analysis (21 trials) found ALCAR produced small but consistent improvement on cognitive batteries in MCI and mild Alzheimer's. Effect size modest; trial doses 1.5–2 g/day; effects develop over 8–12 weeks. Better evidence than ginkgo or vitamin E in this space.
Vitamin D3 — correct deficiency
1000–2000 IU/day; target 30–50 ng/mL serum 25-OH-D
Vitamin D deficiency is associated with cognitive decline in observational data; trial evidence for cognitive endpoints is mixed. Test and correct any deficiency; expect modest benefit at best. Adjacent musculoskeletal and falls-prevention value adds rationale.
B-complex (B12 + folate + B6)
B12 500–1000 mcg + folate 800 mcg + B6 20 mg/day if homocysteine >13 μmol/L
The VITACOG trial (Smith 2010) showed B-vitamin supplementation slowed brain atrophy in MCI patients with elevated homocysteine. The effect was concentrated in those with omega-3 sufficiency. Test homocysteine; supplement to lower in elevated cases.
Citicoline (CDP-Choline)
500–2000 mg/day
Some trial-level signal in vascular cognitive impairment and post-stroke cognitive recovery. Effect in non-vascular MCI is less clear. Choline precursor; modest cholinergic support. Reasonable consider for vascular-pattern MCI; less so for amnestic MCI.
The Mediterranean / MIND-diet layer (bigger than any supplement)
- MIND diet adherence — observational data (Morris 2015) associate with 53% slower cognitive decline at top-tertile adherence. Berries, green leafy vegetables, whole grains, beans, fish, olive oil, poultry, limit red meat, butter, cheese, pastry, fried food.
- Aerobic exercise (150+ min/week) — meta-analytic effect on cognition in MCI; the strongest non-pharmacological intervention.
- Cognitive engagement — language learning, music, social complexity; observational protective effect on conversion.
- Sleep optimisation — including treating obstructive sleep apnoea (associated with accelerated cognitive decline).
- Vascular risk control — BP, lipids, glucose, smoking cessation. Outsizes supplement effects.
- Hearing aids for hearing loss — Lancet Commission identifies hearing-loss treatment as the largest modifiable dementia risk factor.
What to skip
- Ginkgo biloba — large outcome trials (GEM, GuidAge) found no preventive effect on dementia or cognitive decline. Bleeding-interaction concerns. Skip.
- Vitamin E (high-dose) — older AD trial data favoured 2000 IU/day in moderate AD; in MCI, ADCS-MCI trial found no benefit and meta-analyses raise mortality concerns at chronic high doses. Skip the chronic high-dose strategy.
- Coconut oil / MCT oil — small symptomatic signal in advanced AD; not validated for MCI prevention.
- "Memory enhancer" proprietary blends — typically expensive combinations of underdosed ingredients.
- Curcumin (alone) — promising in vitro; clinical-trial cognitive endpoints disappointing.
- Low-dose lithium orotate — promising older signals; recent trial evidence has not confirmed cognitive benefit at supplement doses.
- Anticholinergic medications — not a supplement note, but worth saying: review medication list with prescriber. Diphenhydramine, oxybutynin, tricyclics, and many others contribute to cognitive load and are common preventable contributors.
The escalation ladder
Memory clinic evaluation, brain MRI, B12/TSH/depression screen, sleep study if indicated, medication review, vascular risk control, MIND-pattern eating, aerobic exercise, supplement stack as above. If progressing or biomarker-supported early Alzheimer's: discuss disease-modifying therapy (lecanemab, donanemab) with neurology — meaningful side-effect profile requiring MRI monitoring. Cholinesterase inhibitors (donepezil) are generally not recommended for pure MCI but useful in mild dementia.