There is no single best medication for dementia. The right choice depends on the type of dementia, how far it has progressed, and which symptoms are most disruptive. For Alzheimer’s disease, the most common form, treatment typically starts with a cholinesterase inhibitor for mild to moderate stages and adds memantine for moderate to severe stages. Newer antibody-based infusions can slow the disease itself but only qualify for people in the earliest phase.
Cholinesterase Inhibitors for Mild to Moderate Stages
Cholinesterase inhibitors are the most widely prescribed dementia medications and have been in use for decades. They work by preventing the breakdown of a chemical messenger involved in memory and learning, keeping more of it available in the brain for longer. Three are currently approved: donepezil, rivastigmine, and galantamine. All three target the same problem, but they come in different forms. Donepezil is a once-daily pill, rivastigmine is available as a skin patch (which can reduce nausea), and galantamine comes in an extended-release capsule.
These drugs do not stop or reverse dementia. They can temporarily stabilize or modestly improve memory, attention, and the ability to handle daily tasks. The benefit varies from person to person, and the effect tends to fade over months to a couple of years as the disease progresses. Common side effects include nausea, diarrhea, and loss of appetite, which are usually mild and often ease after the first few weeks.
Memantine for Moderate to Severe Stages
Memantine works differently. Instead of boosting a chemical messenger, it shields brain cells from damage caused by overactivity of a specific signaling system involved in learning and memory. When that system stays switched on too aggressively, as it does in Alzheimer’s, it becomes toxic to neurons. Memantine dials that activity back to a safer level.
It is approved specifically for moderate to severe Alzheimer’s and has no meaningful benefit in the mild stage. For people who qualify, it can improve the ability to perform daily activities like dressing and eating, reduce agitation, and slow the worsening of memory loss. It is generally well tolerated, with side effects like dizziness and headache occurring infrequently. It is also relatively inexpensive compared to newer treatments.
Doctors often add memantine on top of a cholinesterase inhibitor rather than switching. A meta-analysis of nearly 2,000 patients found that this combination significantly improved scores on a test designed for severe cognitive impairment compared to donepezil alone, though it did not show a clear advantage on a broader screening tool. In practical terms, the combination may help people with advanced disease hold on to functional abilities a bit longer.
Newer Antibody Infusions That Target Amyloid Plaques
Two newer medications, lecanemab and donanemab, represent a fundamentally different approach. Rather than managing symptoms, they target and clear the amyloid plaques that build up in the brains of people with Alzheimer’s. Both are given as intravenous infusions, lecanemab every two weeks and donanemab every four weeks.
In an 18-month clinical trial published in the New England Journal of Medicine, lecanemab reduced the rate of cognitive decline by about 25% compared to placebo and removed a substantial amount of brain amyloid. Donanemab showed similar results in its own large trial. These are not cures, but they are the first treatments shown to meaningfully slow the progression of the underlying disease.
The catch is eligibility. Both drugs are approved only for people with mild cognitive impairment or mild dementia who have confirmed amyloid buildup on a brain scan or spinal fluid test. By the time dementia reaches the moderate stage, these treatments are not indicated. They also carry a risk of brain swelling and small brain bleeds, which are usually detected on routine monitoring scans and often cause no symptoms, but can occasionally be serious.
Cost is another significant barrier. Annual Medicare spending per patient for lecanemab runs roughly $20,000 to $26,000, and that does not include the brain scans, infusion center visits, and regular monitoring required throughout treatment.
Medications for Agitation and Behavioral Symptoms
Many people with dementia eventually develop agitation, aggression, anxiety, or hallucinations. These symptoms can be more distressing for families than memory loss itself. For a long time, there was no FDA-approved medication specifically for dementia-related agitation. That changed in May 2023, when brexpiprazole became the first drug approved for this purpose in Alzheimer’s patients. It works by modulating dopamine and serotonin activity in the brain and is taken daily as a pill, with the dose gradually increased over about two weeks.
Before brexpiprazole, doctors relied on off-label options. Certain antidepressants, particularly citalopram and sertraline, have shown modest benefits for agitation. Older antipsychotics like risperidone and quetiapine are sometimes used, but they carry risks including sedation, falls, and a small increase in mortality in older adults with dementia. These are typically considered only after non-drug strategies like adjusting the environment, establishing routines, and identifying pain or discomfort have been tried.
How Treatment Differs by Dementia Type
Not all dementia is Alzheimer’s, and the type matters when choosing medication. For vascular dementia, caused by reduced blood flow to the brain from strokes or small vessel disease, the evidence for cholinesterase inhibitors and memantine is weaker. International guidelines generally support their use when Alzheimer’s is also present alongside vascular disease, which is common, but recommendations for pure vascular dementia are mixed. Managing the underlying vascular risk factors, particularly blood pressure, is considered at least as important as any dementia-specific drug.
Lewy body dementia requires particular caution. Cholinesterase inhibitors, especially rivastigmine, can help with both cognitive and behavioral symptoms in this form of dementia. But antipsychotic medications, which might be prescribed for the vivid hallucinations that are a hallmark of the disease, can be dangerous. An estimated 30 to 50% of people with Lewy body dementia experience severe reactions to standard antipsychotic drugs, including dramatically worsened movement problems and confusion. Some reactions can be fatal. If an antipsychotic is absolutely necessary, quetiapine and pimavanserin are considered the safest options. Pimavanserin works on serotonin receptors rather than dopamine, so it does not worsen the motor symptoms that overlap with Parkinson’s disease.
Matching the Medication to the Stage
A practical way to think about dementia medications is by disease stage, since options narrow as the condition advances:
- Mild cognitive impairment or early mild dementia: Cholinesterase inhibitors are typically started here. Amyloid-targeting infusions like lecanemab or donanemab may be an option if amyloid plaques are confirmed.
- Moderate dementia: Memantine is added, usually alongside the existing cholinesterase inhibitor. Amyloid-targeting drugs are no longer indicated.
- Severe dementia: The combination of a cholinesterase inhibitor and memantine remains the standard approach. Treatment goals shift increasingly toward comfort and managing behavioral symptoms.
None of these medications halt dementia or restore lost function. Their value lies in buying time: preserving the ability to recognize family, manage basic self-care, or hold a conversation for months longer than would otherwise be possible. The “best” medication is the one that addresses your most pressing symptoms at the current stage while carrying risks you and your doctor find acceptable.