Alzheimer’s dementia has no known cure and the effectiveness of drug and non-drug treatments for improving symptoms and quality of life is uncertain. To learn more about the effectiveness of current treatments, researchers from the University of Minnesota School of Public Health (SPH) and the Minneapolis VA Health Care System collaborated to conduct a systematic review of published studies of medications and supplements used for addressing Alzheimer’s dementia in older adults. 

The review, published in the Annals of Internal Medicine, is intended to inform clinical practice and advise new guidelines on treatment for Alzheimer’s dementia. Professor Howard Fink from the University of Minnesota Medical School led a team from SPH’s Minnesota Evidence-Based Practice Center in conducting the review. 

The researchers analyzed 67 treatment trials that met their eligibility requirements based on the study type, length, and other factors. Their findings suggested that few existing treatments have clear evidence of benefit in treating dementia:

• Two prescription drugs — cholinesterase inhibitors and memantine — slightly reduced cognitive decline for up to 6 months;
• Cholinesterase inhibitors slightly reduced reported functional decline for up to 6 months;
• For both of these effects, the difference in effectiveness between the drug and placebo use was too small to know whether benefits are of clinical importance;
• The evidence for drugs specifically used for behavioral and psychological symptoms of dementia was insufficient for the researchers to draw conclusions about benefits and harms;
• The evidence for over-the-counter supplements was almost entirely insufficient to draw conclusions for any outcomes;
• Few studies reporting on cognition and function were longer than six months, and few reporting on behavioral and psychological symptoms were longer than 12 weeks, which makes the longer-term effects of the medications unclear.

“We found that the drugs that are FDA-approved for Alzheimer’s have very modest effects,” says Fink. “And the effects they have are for symptoms only.”

Fink explained that the medications are not disease-modifying drugs, and cannot slow or stop the progression of dementia. 

“If we had better drugs, no one would spend any time talking about these medications. They might produce a small benefit for symptoms, but on average it is small enough that if an individual patient is doing about the same after 6 months, I will have no idea if that is because of the drug or not.”

For over-the-counter supplements, few studies met the review’s eligibility requirements, and those that did simply didn’t provide enough evidence to determine if they work or not.

Notably, the review sought, but did not identify any eligible trials for medical marijuana. 

“We wanted to look at that for treatment of behavioral symptoms in Alzheimer’s,” says Fink. “The medical marijuana programs in more than 10 states include Alzheimer’s as a qualifying condition for medical marijuana, but when we last updated our literature search for this review in November 2019, we found no eligible studies of cannabinoids for Alzheimer’s. This research is really lacking.”