What Medical Treatments Can Do for Alzheimer's

Medications for Alzheimer's do not stop or reverse the disease, but some can slow cognitive decline for a period of time, usually measured in months. The two main classes are cholinesterase inhibitors (donepezil, rivastigmine, galantamine) and memantine, a drug that works through a different mechanism. A newer class called monoclonal antibodies — specifically aducanumab and lecanemab — targets amyloid plaques in the brain and may slow decline in early-stage disease, though they carry risks and require regular brain imaging to monitor for side effects.

Which medication a doctor prescribes depends on the stage of disease, other health conditions, and how the person tolerates the drug. Starting doses are usually low and increased gradually. The goal is not cure but maintaining function longer — delaying the point where someone needs more intensive care.

Key Takeaways

  • Cholinesterase inhibitors and memantine are the oldest Alzheimer's drugs and work best in mild to moderate stages; they slow decline but do not stop it.
  • Lecanemab (Leqembi) is a newer amyloid-targeting drug that may slow early-stage decline more than older drugs, but requires monthly infusions and regular MRI scans to check for brain swelling.
  • All Alzheimer's medications have side effects — nausea, diarrhea, dizziness, and heart rhythm changes are common — and not everyone tolerates them.
  • A neurologist or geriatrician typically prescribes and monitors these drugs; your primary care doctor can also manage them once started.
  • Insurance coverage varies widely; Medicare Part D covers most oral drugs, but newer infusion drugs may require prior authorization or have high out-of-pocket costs.

Cholinesterase Inhibitors: The Standard First-Line Drugs

Cholinesterase inhibitors work by preserving acetylcholine, a brain chemical involved in memory and thinking. The three drugs in this class — donepezil (Aricept), rivastigmine (Exelon), and galantamine (Razadyne) — are roughly equivalent in effectiveness. Donepezil is the most commonly prescribed because it is taken once daily, while rivastigmine and galantamine require twice-daily dosing.

These drugs are used in mild to moderate Alzheimer's. A doctor typically starts at the lowest dose and increases it over weeks to reach the therapeutic dose. The goal is to find the highest dose the person can tolerate without side effects becoming unmanageable. Common side effects include nausea, vomiting, diarrhea, loss of appetite, and dizziness. Some people also experience muscle cramps or slow heart rate, which is why a baseline heart rhythm check (EKG) is often done before starting.

The benefit is modest — studies show these drugs may slow decline by a few months on average — but for some people the difference is noticeable. If a person stops tolerating the drug or shows no benefit after several months, a doctor may switch to a different class or try a different cholinesterase inhibitor.

Memantine: A Second-Line or Combination Option

Memantine (Namenda) works differently than cholinesterase inhibitors. It regulates glutamate, another brain chemical, and is approved for moderate to severe Alzheimer's. It is often added to a cholinesterase inhibitor rather than used alone, though it can be used as a single drug if someone cannot tolerate cholinesterase inhibitors.

Memantine is taken twice daily (or once daily in extended-release form). Side effects are generally milder than cholinesterase inhibitors — dizziness, confusion, and headache are most common — and it is often better tolerated by people with stomach problems or heart conditions. Like cholinesterase inhibitors, the benefit is modest and measured in slowing decline rather than improvement.

Lecanemab and Amyloid-Targeting Drugs: Newer Options for Early Disease

Lecanemab (Leqembi) is a monoclonal antibody that targets amyloid-beta plaques in the brain. It was approved by the FDA in 2023 for mild cognitive impairment or mild dementia due to Alzheimer's disease. In clinical trials, it slowed cognitive decline by about 35 percent over 18 months compared to placebo — a larger effect than older drugs, though still modest.

Lecanemab is given as an intravenous infusion every two weeks. Treatment requires a baseline brain MRI and repeat MRIs during treatment to check for amyloid-related imaging abnormalities (ARIA) — swelling or microhemorrhages in the brain that can occur as amyloid clears. Some people develop no symptoms from ARIA; others experience headache, confusion, or vision changes. If ARIA is detected, the infusion may be paused or stopped.

Lecanemab is expensive — the list price is roughly $26,500 per year — and insurance coverage varies. Medicare covers it, but prior authorization is often required, and the person must meet specific criteria (confirmed amyloid pathology on PET scan or CSF test, mild cognitive impairment or mild dementia stage). Out-of-pocket costs depend on the plan and whether the person has reached their deductible or out-of-pocket maximum.

Another amyloid-targeting drug, aducanumab (Aduhelm), was approved but has limited use due to controversy over its clinical benefit and safety concerns. Some insurance plans do not cover it.

How Doctors Decide Which Drug to Start

A neurologist or geriatrician typically makes the initial choice based on disease stage, other medical conditions, and the person's ability to tolerate side effects. For mild to moderate disease without contraindications, a cholinesterase inhibitor is usually the first choice because it is oral, inexpensive, and well-studied. Memantine may be added later or used if cholinesterase inhibitors are not tolerated.

For mild cognitive impairment or mild dementia with confirmed amyloid pathology, lecanemab may be considered, though the person must be willing to commit to biweekly infusions and regular MRI monitoring. Some people choose not to pursue lecanemab because of the burden of infusions, the cost, or the risk of ARIA.

Once a drug is started, the doctor monitors the person for side effects and, in some cases, cognitive decline. If side effects are severe, the dose is reduced or the drug is stopped. If there is no benefit after several months, a switch to a different drug may be tried, though this is not always done.

Managing Side Effects and Tolerability

Side effects are common with all Alzheimer's drugs and are often the reason people stop taking them. For cholinesterase inhibitors, nausea and diarrhea can be reduced by taking the drug with food, starting at a very low dose, or switching to a different formulation (for example, rivastigmine patch instead of oral). If nausea persists, an anti-nausea medication can be prescribed alongside.

Heart rhythm changes (slow heart rate or irregular heartbeat) are less common but serious. A baseline EKG before starting and periodic checks during treatment help catch these early. If heart rate drops too low, the dose is reduced or the drug is stopped.

For lecanemab, the main concern is ARIA. Headache, confusion, vision changes, or unusual behavior during treatment should be reported to the doctor when ready, as they may signal ARIA. Regular MRI scans catch asymptomatic ARIA, which is why imaging is mandatory.

Insurance Coverage and Cost

Cholinesterase inhibitors and memantine are inexpensive — generic versions cost $10 to $50 per month — and are covered by Medicare Part D, most commercial insurance, and Medicaid in all states. Out-of-pocket cost depends on the plan's formulary tier and the person's deductible.

Lecanemab is expensive and coverage varies. Medicare covers it but requires prior authorization and confirmation that the person meets criteria (mild cognitive impairment or mild dementia stage, amyloid positivity on imaging or biomarker testing). Commercial insurance coverage is less consistent; some plans deny coverage or require high out-of-pocket payments. The infusion itself is usually covered if the drug is approved, but the required MRI scans may have separate costs.

If cost is a barrier, the drug manufacturer may offer copay information programs. A social worker or patient advocate at the infusion center can help navigate these.

Frequently Asked Questions

Can Alzheimer's medications cure the disease?

No. These medications slow cognitive decline for a period of time but do not stop or reverse Alzheimer's. The disease continues to progress; the drugs delay that progression by months, not years.

What happens if someone stops taking their Alzheimer's medication?

Cognitive decline typically accelerates back to the rate it would have been without the drug. There is no "rebound" effect, but the benefit of the medication is lost. Stopping should be discussed with the doctor, especially if the reason is side effects — a different drug or dose adjustment may be an option.

Do all Alzheimer's patients benefit from medication?

No. Some people show no measurable slowing of decline, and others cannot tolerate side effects. A trial of 8 to 12 weeks is reasonable to assess benefit; if there is no improvement and side effects are significant, stopping or switching is appropriate.

Is lecanemab better than older Alzheimer's drugs?

Lecanemab showed a larger effect in clinical trials, but the absolute benefit is still modest — slowing decline by several months. It is only approved for early-stage disease and requires frequent infusions and MRI monitoring. Older drugs are oral, less expensive, and have a longer safety track record.

Can someone take both a cholinesterase inhibitor and memantine?

Yes. This combination is common in moderate to severe Alzheimer's and is supported by clinical guidelines. The drugs work through different mechanisms, so combining them may provide more benefit than either alone.