Medically reviewed by Shilpa Amin, M.D., CAQ, FAAFP, MSCP- Written by Jill Seladi-Schulman, Ph.D. - Updated on October 14, 2024

Key takeaways

• Both Alzheimer’s disease (AD) and Parkinson’s disease (PD) are neurodegenerative diseases that share similarities such as gradual onset, affecting older adults, and unusual protein accumulations in the brain, but they differ in symptoms, treatment, and risk factors.
• While there is no cure for either AD or PD, treatments are available to manage symptoms and improve the quality of life, including drugs and nondrug therapies like physical and occupational therapy.
• Key differences between AD and PD include that PD primarily affects movement, while AD mainly impacts cognitive functions like memory, communication, and reasoning. While older age and family history are risk factors for both, specific risks like pesticide exposure are more associated with PD.

Neurodegenerative diseases cause progressive damage to cells in the nervous system. These diseases can affect functions such as memory, behavior, and movement.

Alzheimer’s disease (AD) and Parkinson’s disease (PD) are two of the most common neurodegenerative diseases. While they share some similarities, they also have important differences.

What is Alzheimer’s disease?

AD is the most common type of dementia. Dementia is a progressive loss of cognitive function. This includes things such as thinking, memory, and problem-solving skills.

People with AD have abnormal accumulations of two proteins in their brains:

• beta-amyloid outside of nerve cells (amyloid plaques)
• tau protein inside of nerve cells (neurofibrillary tangles)

The underlying cause of these changes remains unknown. However, their presence is associated with the death of nerve cells, leading to the symptoms of AD.

What is Parkinson’s disease?

PD is a condition where nerve cells in a part of the brain involved in movement become damaged and begin to die, leading to progressive problems with movement.

PD may also lead to nonmotor symptoms and changes in memory, thinking, and behavior.

People with PD have accumulations of the protein alpha-synuclein in their nerve cells called Lewy bodies. Experts believe that Lewy bodies contribute in some way to the damage and death of nerve cells in PD.

Read more here: The Similarities and Differences Between Alzheimer's and Parkinson's

A columnist shares a notable glossary of Parkinson’s disease terminology

Written by Mollie Lombardi | March 2, 2026

When you are diagnosed with a chronic and complex disease like Parkinson’s, it can be like learning a new language.

Words like “gait” (the body’s posture while walking), “dyskinesia” (uncontrolled, involuntary movements affecting the arms, legs, head, or whole body), “micrographia” (tiny handwriting), and other strange-sounding words suddenly show up in everyday conversation. It can feel like you’re a walking medical encyclopedia, not a person.

I’ve been there. So, in the spirit of solidarity, I’ve put together my own glossary of Parkinson’s disease terminology to share with you. Here it goes:

Hitch in your Giddyup: This is when you just can’t walk right and start to shuffle or drag a foot behind you. Instead of smooth movement, it looks like you have sand in your gears. It happens when you have balance and gait problems and slow movements, also called bradykinesia. It’s also how my husband described the changes he’d seen in me when we met with a neurologist for the first time. Usage: “She’s got a hitch in her giddyup, doc!”

Halulus: I wish I could take credit for this one, but it’s from the Apple TV series “Shrinking.” The show tells the story of a multigenerational group of friends, one of whom has Parkinson’s disease. This character, played by Harrison Ford, has hallucinations, which the others fondly refer to as “halulus.”

Parkinson’s disease-related psychosis, which includes hallucinations, affects 20%-40% of people with Parkinson’s. Usage: “I hope if I have halulus someday, I’m in a bath with Jason Momoa.”

Read more here: A vocabulary lesson Parkinson's families will intimately understand