Dementia medications — what they do and what they can't do
Reviewed by Dr. James Hartfield, M.D.
Dementia medications like donepezil and memantine cannot cure or stop dementia. They help about a third of patients maintain better cognitive function for a period of months, have no effect on another third, and worsen symptoms in the rest. More than 6 million Americans are living with Alzheimer's disease, according to the Alzheimer's Association, and understanding what these drugs realistically offer helps you make informed decisions with your parent.
When your parent gets a dementia diagnosis, the first question is almost always about medication. Can we slow this down? Can we stop it? What can we actually expect from these drugs? I remember sitting in my mom's neurologist's office thinking the doctor was being vague on purpose, but the truth is simpler and harder at once: dementia medications help some people with some symptoms, but they can't reverse what's happening. They can't cure dementia, and they can't stop it. What they can do is sometimes keep things from getting worse quite as fast, and that matters more than it sounds.
The medications your parent's doctor might suggest are usually cholinesterase inhibitors like donepezil, rivastigmine, or galantamine, or sometimes memantine. These aren't new magic drugs. They've been around for years. The research shows they help about a third of people, don't help a third, and slightly worsen symptoms in the remaining third. Nobody knows in advance which group your parent will be in. You won't know until you try it and watch carefully.
This uncertainty is what makes the decision so hard. You're not choosing between a cure and nothing. You're choosing between "maybe this will help a little" and "we'll try something else if it doesn't." And if nothing works, you haven't lost anything except the hope you had beforehand. That's harder than it sounds.
Understanding the Choice
These medications try to keep the brain's remaining chemical messengers working more effectively, but they cannot repair the underlying nerve damage or stop the disease from progressing. As dementia progresses, certain neurotransmitters become depleted, and these drugs try to keep what's left working better. In the early stages of Alzheimer's disease, some people do notice their thinking is a bit clearer or they have fewer moments of confusion. The medication doesn't fix the underlying disease. It's trying to help the symptoms while the disease keeps progressing underneath.
What these medications absolutely cannot do is stop the decline. They cannot prevent progression to the next stage. If your parent is diagnosed with mild cognitive impairment or early-stage dementia, the medication might slow the progression by a few months, but it won't stop it. Your parent will likely still decline. The medication just might make that decline happen a little slower, or make their good days a little better. That's the honest version.
When your parent refuses medication, it's worth understanding why. Some older adults decline because they don't feel sick, don't want to take another pill, or don't believe a medication will help. Sometimes they're right to be skeptical. If they're not forgetting much, not experiencing confusion, functioning okay, the medication might not make any noticeable difference. If they're already in late-stage dementia, medication rarely helps much. But if they're in that earlier window, the question becomes whether the small chance of a small benefit is worth the side effects and the daily reminder that something is wrong.
This is your role in the decision: not to convince them to take it, but to understand what they're afraid of and what they hope for. If they're refusing because they deny they have dementia, that's a different conversation than if they're refusing because they've decided the side effects aren't worth it. Listen to what they're actually saying underneath the "no."
The Risks and Benefits
Nausea, diarrhea, dizziness, and vivid nightmares are common side effects of cholinesterase inhibitors, and these side effects are sometimes worse than the symptoms the medication is meant to treat. Nausea and diarrhea are common with cholinesterase inhibitors. Some people feel dizzy or develop headaches. Donepezil can cause vivid dreams or nightmares that wake your parent in distress. Memantine sometimes causes dizziness or confusion, which seems backwards when you're already dealing with cognitive problems. These aren't rare side effects that happen to someone else. They happen to a lot of people.
The nausea can be managed sometimes by taking the medication with food or at a different time of day. Your parent's doctor should start with a low dose and increase slowly if tolerated. This "start low, go slow" approach is important because it gives the body time to adjust. But sometimes people feel worse on medication than they did before starting it, and if that's happening after several weeks of gradual increases, it's worth stopping and trying something else or nothing at all.
How long does it take to know if a medication is working? Weeks to a couple of months usually. You need to watch carefully during this time. Is your parent having fewer moments of confusion? Are they able to follow conversations better? Are they initiating activities more? Or are you seeing no change, or worse change? You and your parent together are monitoring something subtle that happens slowly. The decline with dementia is gradual anyway, so catching whether medication is actually helping requires paying close attention.
If the medication doesn't help after a fair trial, you stop it. Your parent goes back to where they were before. But here's the thing: if medication does help, when should you stop? With many chronic diseases, you take medication until it's no longer needed or it causes harm. With dementia, the disease progresses regardless. In later stages, medication often doesn't help much at all, and people stop taking it because it causes problems or because the side effects outweigh any benefit. This is a conversation to have with the doctor before your parent declines too far to participate: what does success look like with this medication, and what would indicate it's time to stop?
Your Role
You are the person who observes your parent daily and translates those observations into information the doctor can act on, because your parent may not remember or think to report changes themselves. If your parent seems a bit less confused, they're sleeping better, they're initiating conversations more often, that's worth noting. Bring this to the appointment. If they're nauseated every morning, having accidents that they weren't before, sleeping poorly from nightmares, that also goes to the doctor. You're the translator, because your parent may not remember to mention symptoms, or may not think they're important enough to bring up.
Communication with the doctor means more than just reporting symptoms. It means asking questions about what you're seeing. If your parent seems to be declining despite medication, ask whether the medication is still working or whether the disease is progressing anyway. Ask whether the dose needs adjustment. Ask whether it's time to try something different. Ask whether continuing makes sense given your parent's overall health. A good doctor will answer these questions honestly, even if the answer is "I'm not sure, let's watch and see."
You're also managing expectations, which means yours as much as your parent's. The medication won't fix this. It won't make them the way they were. It might help a little with memory or confusion, or it might not help at all. The disease will progress. Your job isn't to make the medication work miracles. Your job is to help your parent weigh whether trying it is worth it, to watch for side effects and actual changes, and to talk to the doctor about whether it's still helping. The medication is a tool, not a cure, and tools are useful but limited.
As your parent's dementia progresses, their ability to participate in these decisions will change. That's why these conversations need to happen early, while they can still tell you what they want. Do they want to try medication if it might help a little? What matters most to them—memory, independence, comfort? If medication interferes with comfort, would they want to stop it? These aren't questions with right answers, but your parent gets to answer them while they can.
Frequently Asked Questions
How long should we try a dementia medication before deciding it does not work?
Most doctors recommend two to three months at a therapeutic dose. During that time, watch for subtle improvements in clarity, conversation, or daily functioning. If there is no change or symptoms worsen, stopping the medication is reasonable. Discuss the timeline with the doctor before starting.
Will the medication make my parent "normal" again?
No. At best, the medication helps maintain current function a bit longer or produces modest improvement in symptoms like confusion or memory. It does not reverse the disease or restore lost cognitive ability. Setting realistic expectations prevents the disappointment that leads some families to abandon helpful medication too early.
My parent has late-stage dementia. Should they still take dementia medication?
In later stages, the benefit of these medications diminishes significantly. Many doctors recommend stopping them when a patient has advanced dementia, especially if side effects are causing discomfort. This is a conversation about comfort and quality of life, not about giving up.
Are the newer dementia drugs like lecanemab better?
Newer drugs targeting amyloid plaques in the brain have shown modest ability to slow decline in early-stage Alzheimer's, but they carry serious risks including brain swelling and bleeding. They require regular brain imaging to monitor for complications. As of 2024, the Alzheimer's Association notes these drugs are only appropriate for early-stage patients. Talk to your parent's neurologist about whether they qualify and whether the risks are acceptable.