The doctor diagnosed your loved one with Alzheimer’s disease. But something doesn’t quite fit. They’re seeing people who aren’t there. Their thinking seems sharp one moment and confused the next. They’ve developed a tremor that wasn’t mentioned in anything you read about Alzheimer’s.
What you might actually be dealing with is Lewy body dementia, a different type of dementia that’s frequently confused with Alzheimer’s disease. While both conditions affect memory and thinking, they have distinct features that set them apart.
Lewy body dementia and Alzheimer’s disease share overlapping symptoms, which is why doctors who aren’t familiar with LBD’s unique characteristics often mistake one for the other. This misdiagnosis matters because treatments that help Alzheimer’s disease may be dangerous for people with Lewy body dementia.
This guide explains the key differences and similarities between Lewy body dementia and Alzheimer’s so you can recognize what you’re dealing with and ensure your loved one gets appropriate care.
Is Lewy Body Dementia the Same as Alzheimer’s Disease?
No, Lewy body dementia and Alzheimer’s disease are two distinct conditions, though they both cause progressive problems with thinking and memory. The differences lie in which symptoms appear first, how many other symptoms appear, how they progress, and what’s happening in the brain at a cellular level.
What Are the Main Differences Between Lewy Body Dementia and Alzheimer’s?
The most noticeable differences between LBD and Alzheimer’s appear in which symptoms show up first and how many other symptoms appear. If you’re trying to figure out whether your loved one might have LBD instead of Alzheimer’s, or vice versa, these are the clearest signs to look for.
Memory Loss Happens Differently
Alzheimer’s typically announces itself with memory problems. Your loved one might forget recent meals or conversations, struggle to recall familiar names, or repeat the same question multiple times. Memory loss is usually the first thing families notice and the reason they seek medical help.
Lewy body dementia affects memory too, but it’s rarely the main issue, especially early on. Your loved one might remember yesterday’s events perfectly fine but struggle to stay focused on what you’re saying right now, or may need time to respond. They have trouble organizing their thoughts, finding the right words, or figuring out the sequence of steps for familiar tasks. The problem isn’t storing memories so much as using their brain in the moment. The problems are with executive function, meaning with multitasking and problem-solving
Hallucinations Tell a Clear Story
This is one of the easiest ways to spot the difference.
Most people with Lewy body dementia experience visual hallucinations, usually within the first few years. These aren’t vague shadows or unclear shapes. They’re detailed, vivid images. Your mother might calmly tell you about the children playing in the corner, seeing small animals, or the man sitting in the empty chair. She sees them as clearly as she sees you. These hallucinations happen repeatedly, often with the same characters or themes.
Hallucinations can happen in Alzheimer’s disease, but they’re uncommon. When they do occur, it’s usually in late stages after years of memory decline.
Alertness Changes Throughout the Day (Fluctuations)
Watch how cognitive ability changes over the course of a day, and you’ll see a major difference.
People with Lewy body dementia can seem completely normal and engaged at breakfast, then by lunch, they seem distant. Two hours later, they may be back to themselves. These fluctuations happen unpredictably and can be dramatic. One minute, they’re having a coherent conversation about current events, the next, they’re struggling to process what you’re saying.
Alzheimer’s doesn’t work this way. People with Alzheimer’s have good days and bad days, but they don’t typically swing from clear-headed to confused within the same period.
Movement Problems Appear Early in LBD
Watch how your loved one walks and moves, and you might notice important clues.
Lewy body dementia often causes movement problems that look like Parkinson’s disease. Hands might tremble at rest. Walking becomes slower and a person may shuffle. Getting up from a chair becomes more challenging. Balance becomes shakier. These movement changes can show up early, sometimes even before thinking problems become obvious.
Alzheimer’s doesn’t cause these movement issues until very late in the disease, if at all. Someone with Alzheimer’s typically maintains their usual mobility in early and middle stages, but may eventually have trouble with coordination after many years.
Sleep Problems Look Different
Both conditions disrupt sleep, but in distinct ways.
REM sleep behavior disorder is a hallmark of Lewy body dementia and often shows up years before other symptoms. During normal REM sleep, your body becomes temporarily immobile so you don’t act out your dreams. In people with this disorder, that protective immobility doesn’t work properly. Your loved one physically acts out their dreams, potentially kicking, punching, or shouting during sleep. This can lead to injuries for them or their sleep partner.
Alzheimer’s causes different sleep issues. People might have trouble falling asleep, wake frequently during the night, or experience day-night confusion where they’re awake at 3 AM and sleeping during the day. But they don’t typically act out dreams violently.
What Happens in the Brain
Both conditions involve abnormal proteins damaging brain cells, but the culprits are different.
In Alzheimer’s disease, two proteins cause problems: beta-amyloid and tau. Beta-amyloid forms sticky plaques between brain cells, while tau creates tangles inside them. These deposits kill brain cells, particularly in areas that handle memory and learning. The damage spreads gradually through the brain over many years.
In Lewy body dementia, a protein called alpha-synuclein clumps together inside brain cells. These clumps, called Lewy bodies, interfere with how cells communicate. They show up in multiple brain regions at once, affecting areas that control movement, thinking, sleep, and behavior simultaneously.
Some people have both types of protein deposits. This overlap is why diagnosis can be tricky and why some people show features of both conditions.
Which Progresses Faster: Lewy Body Dementia or Alzheimer’s?
The timeline from early symptoms to advanced disease differs between these conditions, and understanding this can help you plan for the future.
Alzheimer’s typically develops slowly over 8 to 10 years, though some people decline faster and others slower. The progression usually follows a predictable pattern. Early years bring primarily memory problems and mild confusion. Middle years involve increasing difficulty with daily tasks, more significant confusion, and personality changes. Later years require full-time care as the person loses the ability to fully communicate and care for themselves properly.
Lewy body dementia tends to move faster for some, though not all, with many people progressing from diagnosis to advanced stages within 5 to 8 years. But the progression feels different because multiple symptoms may worsen simultaneously rather than in a clear sequence. Cognitive problems, movement difficulties, and behavioral symptoms can advance together, making the decline feel more chaotic and unpredictable than Alzheimer’s steady trajectory.
This doesn’t mean LBD is always worse or faster for everyone. And each person with LBD progresses differently. Some people maintain quality of life for many years with proper treatment and support, while others decline sooner. The key difference is the pattern of decline rather than just the speed.
Why Accurate Diagnosis Matters So Much
Getting the right diagnosis isn’t just about putting a label on what’s happening. It directly affects treatment, safety, and effectiveness.
Medication Safety
People with LBD are extremely sensitive to medications. Some medications commonly prescribed for Alzheimer’s-related behavior problems can be extremely dangerous for people with Lewy body dementia. Traditional antipsychotic drugs, such as haloperidol, should never be given and can cause severe reactions in LBD, including extreme sedation, dramatic worsening of movement problems, and dangerous blood pressure drops.
If your loved one has LBD but their doctor thinks it’s Alzheimer’s, they might prescribe medications for behavior or aggression that could seriously harm them. This happens frequently in emergency rooms and hospitals where staff aren’t familiar with LBD.
Treatment Effectiveness
Medications that enhance brain function work differently for each condition. Drugs like rivastigmine often work better for Lewy body dementia than for Alzheimer’s. People with LBD who have movement problems might benefit from Parkinson’s medications that wouldn’t be prescribed for Alzheimer’s, though some people with LBD may not do well on these medications. Getting the diagnosis right means accessing treatments that actually help rather than receiving treatments designed for a different condition.
Care Planning
The two conditions require different approaches to daily care. Lewy body dementia’s fluctuating alertness means you need flexible schedules and realistic expectations about hour-to-hour changes. The hallucinations require specific strategies that wouldn’t apply to most Alzheimer’s cases. Movement problems create fall risks that need different safety modifications.
Knowing which condition you’re dealing with helps you prepare for these challenges rather than being caught off-guard when symptoms don’t follow the expected pattern.
Treatment Approaches for Each Condition
The treatments that help one condition aren’t always right for the other, and some can actually be dangerous when used incorrectly.
Memory and thinking medications like donepezil, rivastigmine, and galantamine can help both conditions, but they often work better for Lewy body dementia. Many doctors find rivastigmine particularly effective for LBD. These medications don’t stop the disease, but they can improve daily functioning and reduce some behavioral symptoms.
If your loved one has significant movement problems from LBD, their doctor might prescribe carbidopa-levodopa, the main medication for Parkinson’s disease. This can reduce tremor, stiffness, and slowness of movement. People with Alzheimer’s don’t need this medication because movement problems aren’t part of the condition until very late stages, if at all.
Both conditions benefit from non-medication approaches like regular exercise, cognitive activities, social engagement, and consistent daily routines. The specific home modifications and care strategies differ based on which symptoms are most prominent, but the overall principle of maintaining engagement and quality of life applies to both.
Can You Have Both Lewy Body Dementia and Alzheimer’s?
Yes, some people develop both Lewy body dementia and Alzheimer’s disease simultaneously. This is called mixed dementia, and it’s more common than many people realize.
Mixed dementia happens when someone has both the Lewy bodies characteristic of LBD and the plaques and tangles characteristic of Alzheimer’s. Brain autopsies show that many people diagnosed with one condition actually had signs of both.
For families, this creates additional complexity. Your loved one might show the memory problems typical of Alzheimer’s along with the hallucinations and movement issues typical of LBD. The combination can make diagnosis even more challenging and requires doctors to consider both conditions when planning treatment.
The medication sensitivities that apply to Lewy body dementia still apply when someone has mixed dementia. Even if Alzheimer’s is also present, the presence of Lewy bodies means that certain antipsychotic medications remain dangerous.
What Do Lewy Body Dementia and Alzheimer’s Have in Common?
Despite their important differences, LBD and Alzheimer’s share several key features that affect how families experience and manage these conditions.
Both are progressive neurodegenerative diseases, meaning they get worse over time and currently have no cure. In both conditions, abnormal proteins damage and kill brain cells, though the specific proteins involved are different. Both eventually affect a person’s ability to think clearly, remember information, and handle daily activities independently.
The emotional and practical challenges families face are similar with both conditions. You’ll likely experience grief over watching someone you love gradually change. You’ll need to adapt your home and routines to keep them safe. You’ll face difficult decisions about care as the disease progresses. You’ll need increasing levels of support over time.
Both conditions respond to similar caregiving approaches. Maintaining consistent daily routines helps reduce confusion. Staying socially engaged and physically active supports overall wellbeing. Creating a safe, familiar environment reduces anxiety and accidents. Treating the person with dignity and patience preserves their sense of self.
The importance of early diagnosis applies equally to both conditions. Getting the right diagnosis early allows you to access appropriate treatments, avoid dangerous medications, connect with relevant support services, and plan for future care needs while your loved one can still participate in decisions.
Perhaps most importantly, quality of life remains possible with both conditions. While these diseases bring real challenges, many people with Alzheimer’s or LBD maintain meaningful relationships, enjoy activities, and experience moments of joy for years after diagnosis. The key is adapting expectations and care to support what’s still possible rather than focusing solely on what’s been lost.
When the Diagnosis Doesn’t Seem Right
Many families dealing with Lewy body dementia spend months or even years being told their loved one has Alzheimer’s disease. The symptoms don’t quite match what they read about Alzheimer’s, but they trust the doctor’s expertise.
Here are signs the diagnosis might need a second look:
Your loved one was diagnosed with Alzheimer’s, but hallucinations started early and are frequent. Hallucinations happen in Alzheimer’s, but they’re not common, especially in early stages.
The cognitive problems fluctuate dramatically during the day. If your father seems fine at breakfast but can barely hold a conversation by dinner, and then seems better again the next morning, that pattern fits LBD much more than Alzheimer’s.
Movement problems appeared around the same time as thinking problems (or within the first year). If your mother developed a shuffle and tremor along with memory issues, rather than memory problems alone, LBD should be considered.
Medications prescribed for behavioral symptoms made things much worse. If antipsychotic drugs caused severe sedation or worsening confusion, that reaction raises red flags for LBD.
Trust your observations. You know your loved one better than anyone. If something feels off about the diagnosis, seek evaluation from a neurologist who has specific experience with Lewy body dementia, not just general dementia expertise, particularly a movement disorder neurologist..
Finding Answers for Your Family
If you’re questioning whether your loved one has the right diagnosis, or you’re trying to understand which condition best explains what you’re seeing, you’re not alone. Many families struggle with this confusion for months or years.
The combination of symptoms matters more than any single symptom. Alzheimer’s with early, frequent hallucinations is unusual. LBD without movement problems or fluctuating alertness is rare. Look at the overall pattern rather than checking off individual symptoms.
Whether your loved one has Alzheimer’s disease, Lewy body dementia, or both, getting connected with the right resources and support makes a significant difference. Understanding the specific condition helps you prepare for the right challenges, access appropriate treatments, and make informed decisions about care.
If you need help finding a specialist who understands both conditions, have questions about symptoms you’re observing, or just want to talk with someone who understands the complexity of these diagnoses, we’re here to help.
Our helpline is available every day of the year from 8am to 8pm Eastern time at 516-218-2026 or 833-LBDLINE. You can also reach us by email at norma@lbdny.org.
