Because of the limited effectiveness of available pharmacologic agents used to treat Alzheimer's disease and other forms of dementia, studies are being done on a variety of complementary and alternative (CAM) treatment approaches. The amino acid acetyl-l-carnitine (ALC) occurs naturally in the brain and liver. Research findings show that ALC stabilizes nerve cell membranes, stimulates the synthesis of acetylcholine, and increases the efficiency of mitochondrial energy production. ALC is widely used to enhance memory in healthy adults and to treat cognitive impairment in dementia and other neurodegenerative disorders. Few large placebo-controlled studies have been done, and the findings of human clinical trials are inconsistent.
ALC is widely used to improve memory in healthy adults and individuals with Alzheimer's disease
ALC taken in doses of 1.5 to 3.0 grams per day may improve age-related symptoms of cognitive impairment in healthy, nondemented elderly individuals and depressed elderly individuals (Bella, Biondi, Raffaele, & Bennisi, 1990; Cipolli & Chiari, 1990). A small, 18-month open study on individuals with early, mild Alzheimer’s disease found that blood circulation in the precuneus, a brain region involved in visuospatial imagery and memory, is increased in individuals who received ALC in doses of 1.5m/day (Jeong et al 2017).
Double-blind, placebo-controlled studies support that ALC at 1.5 to 3 grams per day may improve overall performance on tests of reaction time, memory, and cognitive performance in demented patients and may slow the overall rate of progression of cognitive impairment (Arrigo, Casale, Buonocore, & Ciano, 1990; Calvani et al., 1992; Thal et al., 1996). A systematic review of 11 double-blind, placebo-controlled studies of ALC in dementia found significant positive effects at weeks 12 and 24 that were not sustained (as measured by the Clinical Global Impression scale) with continued treatment at 1 year (Hudson & Tabet, 2003). At high doses (2 g/day) ALC has been shown to improve memory, word recall, and visuospatial deficits in cognitively impaired, abstinent alcoholics (Tempesta et al., 1990). For unclear reasons, younger demented individuals (i.e., individuals with presenile dementia) may benefit more than older individuals, and 62 years may be the optimal age beyond which ALC loses much of its efficacy (Pettegrew et al., 2000). A few studies suggest that the neuroprotective benefits of ALC may be enhanced when the amino acid is combined with other natural products, including alpha-lipoic acid, Coenzyme Q10, or omega-3 fatty acids (Lolic, Fiskum, & Rosenthal, 1997).
No safety issues
At the doses used to treat cognitive impairment, ALC is well-tolerated, and there are few reports of adverse effects.
While there is some evidence that taking ALC may improve memory and cognitive functioning in both healthy adults and individuals with early Alzheimer’s disease, research findings are inconsistent. More studies need to be done to confirm beneficial effects of ALC on memory, and to determine optimal dosing regimens.