What Are the Treatments for Alzheimer's Disease?

The FDA says the drug is only for those with mild cognitive impairment or mild-stage dementia. At this stage of the illness, the person is still functioning independently. 

The drug appears to raise risk for a side effect called ARIA, for amyloid-related imaging abnormalities. ARIA usually shows as swelling of the brain that may be accompanied by bleeding. In the large Leqembi study, about 17 percent of patients experienced brain bleeding, and 13 percent experienced brain swelling. Most of these side effects disappeared within four months. 

Because people with two copies of the APOE e4 gene variant, which raises risk for Alzheimer's disease, are more likely to experience ARIA, potential patients should be tested for APOE e4. Patients taking blood thinners are also at greater risk of brain bleeds while taking Leqembi.

A review of 31 studies of this and other drugs that clear amyloid plaques, published in March 2023 in the journal Neurology, suggests these drugs may lead to brain shrinkage.

“It may be that as the medication is clearing amyloid out of the brain, it’s decreasing some of the volume with it,” says Gary Small, M.D., chair of psychiatry at Hackensack University Medical Center in New Jersey. 

While amyloid-clearing drugs are a step in the right direction, they may need to be paired with other types of drugs being designed to remove a protein called tau from the brain. In Alzheimer’s disease, tangles of abnormal tau form inside nerve cells, causing problems in communication between nerve cells. Several tau-removing drugs are being tested in people with Alzheimer’s, including Biogen’s BIIB080, which reduced tau levels by more than 50 percent in a very early clinical trial of 46 patients with early disease.

Alzheimer's-slowing drugs in the research pipeline

​A third monoclonal antibody, called donanemab, slowed the loss of thinking and memory skills in a phase 3 study of patients with early stage Alzheimer’s disease. 

This drug “seems to get rid of the amyloid at the core of the plaques,” Leverenz says. “There’s a feeling that this amyloid is what drives symptoms and the progression of the disease early on.” 

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Results of the 18-month study giving donanemab infusions every four weeks compared with placebo suggest that the drug slowed disease progression by an average of four to six months over 18 months of treatment, researchers reported in July in JAMA.

That slowdown in disease progression is important. But brain swelling and bleeds occurred in a few patients, and researchers also observed brain shrinkage in patients taking donanemab. The hope is that donanemab will have a similar safety profile as Leqembi, and will be approved as another monoclonal antibody option for patients, says Joel Salinas, M.D., a cognitive behavioral neurologist at NYU Langone Health in Manhattan.

Researchers, including those supported by AARP and others through the Dementia Discovery Fund, are developing and testing several other approaches to treat Alzheimer’s and other dementias as well. 

Drugs to ease behaviors and other symptoms

Several medications are available to treat certain Alzheimer’s symptoms, and some are used for other forms of dementia as well. These treatments do not slow progression of disease. They include:

• Cholinesterase inhibitors. These drugs prevent the breakdown of a brain chemical called acetylcholine that’s important for memory and thinking, Small says. Three examples are Aricept (donepezil), Exelon (rivastigmine) and Razadyne (galantamine), all approved for Alzheimer’s. Exelon is also approved to treat dementia associated with Parkinson’s disease.
• Namenda (memantine). This drug inhibits the activity of a brain chemical called glutamate, which sends messages between nerve cells. In Alzheimer’s disease, nerve cells make too much glutamate, which causes damage and cell death. Namenda is approved for people with moderate to severe Alzheimer’s disease. The drug can be used on its own, or with a cholinesterase inhibitor, Small says.
• Belsomra (suvorexant). The drug inhibits a brain chemical called orexin, which can keep a person awake. Belsomra is approved to treat insomnia in people with Alzheimer’s disease.

Doctors may also prescribe the drugs below to help treat symptoms that may appear in later stages of the disease:

• Antidepressants such as Zoloft (sertraline) to improve mood and irritability, although recent studies have questioned their effectiveness.
• Antipsychotic medications such as Risperdal (risperidone) or Haldol (haloperidol) for hallucinations, delusions, aggression or agitation. These drugs may not be appropriate for people with Lewy body dementia or Parkinson’s disease dementia, Petersen cautions, as they may worsen behavioral symptoms. 
• The first anti-agitation drug to receive FDA approval, which occurred in May 2023. Rexulti (brexpiprazole) is prescribed for Alzheimer’s-related agitation, from pacing and restlessness to verbal and physical aggression. The drug comes with a black box warning, FDA’s strongest warning, of an increased risk for death in older people with dementia taking the drug.

While there are medications to treat other forms of dementia, they are usually geared to the specific condition, Petersen says. The treatment for vascular dementia, for example, is often aimed at improving blood vessel health, which means getting control of risk factors such as high blood pressure, type 2 diabetes and being overweight.

Editor’s note: This story, originally published Jan. 17, 2024, has been updated with new information.