For early Alzheimer's disease, should the diet go high fat or very low fat?

Christopher M. PalmerMD · psychiatrist, McLean Hospital and Harvard Medical School

A ketogenic diet, high fat and very low carbohydrate, is worth asking a clinician about.

What it rests onA single case report on which he is last author: one patient with Down syndrome and Alzheimer's disease moved to under 20 grams of carbohydrate a day at 70 to 80 percent of calories from fat, with daily fingerstick ketones of 0.8 to 3.0 mmol/L. Her daily-living score rose from 34 to 57 of 78, 6 to 10 weekly seizures stopped within two weeks, and all medications were discontinued by six months. The authors state the competing explanation themselves: the gain may have followed from seizure control rather than from any effect on Alzheimer's pathology. n equals 1, and the paper's first author sells ketogenic books and products, disclosed in print.

Dean Michael OrnishMD · internal medicine and cardiovascular disease; founder and president, Preventive Medicine Research Institute

An intensive multidomain lifestyle programme built on a whole-food plant-based diet at 14 to 18 percent fat is worth asking a neurologist about.

What it rests onA 1:1 randomised controlled trial, 51 patients with MCI or early dementia due to Alzheimer's, 20 weeks against a wait-list control: CGIC p=0.001, CDR-SB p=0.032, CDR Global p=0.037, ADAS-Cog borderline at p=0.053, plasma amyloid beta 42/40 ratio up in the intervention arm and down in controls (p=0.003). Read his own limitations before quoting him: the intervention bundles fifteen or more components including supervised Zoom sessions, delivered meals, exercise, stress management, a support group and eight supplements, so it supports one claim about the package and none about the diet alone. He and a co-author hold equity in Ornish Lifestyle Medicine; a further co-author co-founded the company supplying an optional device in the protocol.