Alzheimer vs Parkinson: What’s the Real Difference?

Written by Nguyenjessica

Published on May 21 2025

Memory slips? Shaky hands? Mood swings? Is it Alzheimer’s or Parkinson’s? At first glance, these two brain diseases seem alike—both affect older adults and worsen over time. But in reality, they show up in very different ways. Knowing the difference is key if you or someone you love is facing symptoms.

This article breaks it all down in plain language. You’ll learn how Alzheimer’s and Parkinson’s impact the brain, what symptoms to look for, how doctors diagnose them, and if it’s possible to have both. Keep reading to get the facts, clear the confusion, and take a step toward better understanding and care.

Alzheimer vs Parkinson: What’s the Real Difference?

Key Points

Alzheimer’s and Parkinson’s start with different symptoms
Alzheimer’s begins with memory loss, while Parkinson’s starts with shaky hands and slow movement. One hits the mind first, the other the body.

Both affect the brain, but in different ways
Alzheimer’s damages memory-related areas with toxic proteins. Parkinson’s affects dopamine levels, causing movement problems.

Some people can have both—called mixed dementia
Though rare, some show signs of both diseases. They may forget things and have trouble moving. These cases need special care.

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Table of content

What are the key symptoms of Alzheimer’s vs Parkinson’s?

How does Alzheimer’s disease affect the brain?

How does Parkinson’s affect the brain?

Do Alzheimer’s and Parkinson’s have similar causes or risk factors?

Are treatments for Alzheimer’s and Parkinson’s the same or different?

Can someone have both Alzheimer’s and Parkinson’s at the same time?

What are the key symptoms of Alzheimer’s vs Parkinson’s?

Alzheimer’s and Parkinson’s are both brain-related conditions, but they show up in very different ways.

People with Alzheimer’s usually first show memory problems, especially short-term memory. They might forget what just happened, ask the same questions again and again, and rely more on reminders or help from others.

Over time, thinking clearly becomes harder. Planning, solving problems, or even finishing daily tasks takes much more effort. They might also get confused about dates or places and sometimes get lost.

Language can be a struggle too. It becomes hard to find the right words, and conversations feel difficult. Emotionally, they may seem anxious, depressed, or easily irritated. Many start to avoid social situations. In the later stages, they may no longer recognize loved ones, struggle to communicate, and need full-time care.

Parkinson’s mostly shows up through movement issues. Hands might tremble at rest, movements slow down, muscles feel stiff, and posture becomes unsteady. Walking might look shuffled or slow.

Besides movement, there are also non-motor symptoms. These include mood issues like depression or anxiety, sleep troubles, trouble swallowing, constipation, and blood pressure swings. Speech often becomes soft or flat, and writing can turn very small and hard to read. Facial expressions also fade, making people look like they’re wearing a mask.

Feature

Alzheimer's Disease

Parkinson's Disease

Main Symptoms

Memory loss, cognitive decline,confusion about time and place

Movement disorders (tremor, slow movement,
stiffness, balance problems)

Onset of
Cognitive lssues

Early and prominent

Dementia usually appears in later stages

Movement
Problems

Not common early on

Core symptom from early stages

Speech lssues

Difficulty finding words,language decline

Soft, monotone, or slurred speech

Mood Changes

Anxiety, depression, irritability,behavioral changes

Depression, anxiety,less personality change
early on

Other Symptoms

Hallucinations, delusions.impulsive behavior

Autonomic symptoms (constipation, blood
pressure fluctuations),sleep disorders

How does Alzheimer’s disease affect the brain?

Alzheimer’s disease damages the brain step by step, slowly breaking down how nerve cells work and communicate.

As the disease progresses, many neurons start to fail and eventually die. This leads to brain functions shutting down over time.

What’s behind this damage? Mainly toxic buildup of abnormal proteins. One type, called amyloid, collects outside of neurons. Another, called tau, tangles up inside them. These changes actually begin years before any symptoms appear.

The first parts of the brain hit hardest are the hippocampus and amygdala, which are key for memory and emotions.

As the disease spreads, other areas like the entorhinal cortex, temporal lobe, thalamus, and parts of the frontal and parietal lobes also shrink and lose function. MRI scans show this shrinkage clearly, especially in memory-related regions.

With more neurons dying, the brain keeps shrinking, and cognitive functions slowly decline. People start forgetting things, struggle to think clearly, get confused easily, and eventually need help with everyday tasks.

How does Parkinson’s affect the brain?

Parkinson’s disease mainly affects the brain by causing the gradual loss of dopamine-producing neurons, especially in a region called the substantia nigra, located near the base of the brain. Dopamine is a key chemical that helps control smooth, purposeful movements. By the time symptoms show up, about 60 to 80% of these neurons are already gone.

This loss of dopamine disrupts how signals flow through the basal ganglia, a part of the brain that helps manage movement. That’s what leads to tremors, stiffness, slow movements, and balance problems.

Another major feature of Parkinson’s is the build-up of Lewy bodies—clumps of abnormal proteins, mainly alpha-synuclein, inside nerve cells. These disrupt normal cell function and eventually cause the cells to die.

Parkinson’s also affects brain areas beyond the substantia nigra. It impacts parts of the limbic system and the frontal lobe, which are involved in emotion and thinking. That’s why people often develop depression, anxiety, cognitive decline, or even dementia later in the disease.

And it’s not just dopamine. Other chemicals like norepinephrine are also affected. When those neurons die, it can lead to issues like fatigue, blood pressure problems, and dizziness when standing up.

As the disease progresses, Lewy bodies and cell loss spread to other parts of the brain—including the olfactory bulb, brainstem, thalamus, hypothalamus, and cerebellum—causing broader problems with brain function.

Do Alzheimer’s and Parkinson’s have similar causes or risk factors?

Alzheimer’s and Parkinson’s may look different, but they do share some common risk factors.

Age is the biggest one. For both diseases, the risk rises sharply after age 65.

Genetics also play a role. A family history of Alzheimer’s—especially if someone carries the APOE e4 gene—raises the risk. Parkinson’s also has genetic links, though they involve different genes, particularly those tied to alpha-synuclein.

Lifestyle and vascular health matter too. Smoking, high blood pressure, lack of physical activity, obesity, and poor diet all seem to increase the risk for both conditions. These likely affect the brain through damage to blood vessels.

Environmental toxins—like pesticides—are another shared concern, especially for Parkinson’s.

But there are also key differences between the two.

In the brain, Alzheimer’s is marked by amyloid plaques and tau tangles, while Parkinson’s is known for Lewy bodies made of alpha-synuclein.

Gender differences are also seen. Parkinson’s is more common in men, while Alzheimer’s affects more women—partly because women tend to live longer.

Parkinson’s has some unique risk factors, such as REM sleep behavior disorder, hallucinations, and certain types of movement symptoms. These raise the chance of Parkinson’s-related dementia but aren’t typical in Alzheimer’s.

Finally, higher education and cognitive reserve seem to offer protection in both diseases. A well-trained brain may better handle early damage and delay symptoms.

Risk Factor

Alzheimer's Disease

Parkinson's Disease

Age

Major risk factor, risk risesafter 65

Major risk factor, risk rises after 60-65

Genetics

APOE e4 gene increases risk

Alpha-synuclein and other PD genes involved

Sex

More common in women

More common in men

Protein Pathology

Beta-amyloid plaques,tau tangles

Alpha-synuclein Lewy bodies

Smoking

Increases risk,especially vascular risk

Smoking linked to increased risk ofParkinson's dementia

Hypertension

Increases risk via vascular mechanisms

Increases risk of Parkinson's dementia

Education

Higher education protective

Environmental toxins

Possible link to pesticides

Stronger association with pesticides

Sleep disorders(RBD)

Not typical risk factor

Strong predictor of Parkinson's dementia

Are treatments for Alzheimer’s and Parkinson’s the same or different?

Alzheimer’s and Parkinson’s have different causes and symptoms, so their treatments differ too—though they do share some approaches for managing dementia.

Alzheimer’s treatment focuses on slowing cognitive decline with medications.

Common drugs include cholinesterase inhibitors like donepezil, rivastigmine, and galantamine. These help boost acetylcholine levels in the brain to improve memory and thinking.

For moderate to severe cases, memantine is often used. It works by regulating glutamate, helping protect brain cells.

Recently approved by the FDA, new immunotherapies like lecanemab and donanemab target beta-amyloid plaques. These are designed to slow early-stage disease progression.

Besides medications, non-drug strategies like 40hz therapy ,cognitive training, behavioral therapy, and lifestyle changes—such as healthy eating, regular exercise, and staying socially active—play a big role in managing symptoms and quality of life.

Parkinson’s treatment mainly addresses movement symptoms.

The most common approach is taking levodopa and related drugs to restore dopamine levels and improve motor control. Other options include dopamine agonists, MAO-B inhibitors, anticholinergics, and amantadine.

When medications aren’t enough, deep brain stimulation (DBS) might be considered. This involves placing electrodes in the brain to help manage motor symptoms.

Researchers are also exploring stem cell and gene therapies, which may offer new solutions in the future.

For cognitive symptoms in Parkinson’s dementia, cholinesterase inhibitors—the same drugs used in Alzheimer’s—can be helpful.

Supportive therapies like physical, occupational, and speech therapy are also key in helping patients maintain independence and quality of life.

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Can someone have both Alzheimer’s and Parkinson’s at the same time?

Though not very common, it is possible for someone to have both Alzheimer’s disease and Parkinson’s disease at the same time. This condition is often called mixed dementia or co-existing neurodegenerative disorders.

Studies show that many people with Parkinson’s disease dementia (PDD) also have Alzheimer’s-type changes—between 20% and 60% may show amyloid and tau buildup. Likewise, 30% to 50% of Alzheimer’s patients may have Lewy body pathology found during autopsies.

People with both diseases often show a mix of memory loss, cognitive decline, and motor symptoms like tremors or stiffness. Hallucinations and behavioral changes can also appear, making diagnosis and management more complex.

Autopsy studies confirm that some patients truly have both conditions, either developing them one after the other or at the same time. Experts now recognize that mixed dementia is more common in older adults than we once thought.

When both diseases are present, treatment needs to be tailored carefully, balancing cognitive and motor symptom care. Unfortunately, the outlook tends to be worse in these cases.

Reference
Alzheimer’s Society: What is mixed dementia?
Johns Hopkins Medicine: Parkinson’s Disease and Dementia
Alzheimer’s Association: 10 Early Signs and Symptoms