Patrick Stewart dies at 86 after battles with two forms of dementia

Patrick Stewart, the veteran actor known for his roles in Star Trek and X-Men, died Wednesday in Los Angeles at age 86. His spokesperson, Kelly Bush Novak, said Stewart had been dealing with both Alzheimer's disease and Lewy body dementia. The diagnoses had not been shared with the public before his death.

Lewy body dementia is a progressive condition that impairs a person's ability to think, reason, and process information, according to Johns Hopkins Medicine. The disease takes its name from Lewy bodies, which are abnormal clumps of protein that accumulate inside nerve cells. These clumps inhibit cell function and eventually kill the cells, according to the U.S. Department of Health and Human Services.

Early symptoms often include visual hallucinations of people or objects that are not present, as noted by the Mayo Clinic. The condition also affects attention, spatial awareness, and memory, similar to Alzheimer's disease. Physical symptoms can include acting out dreams during REM sleep, bladder control issues, and sudden dizziness or falls caused by drops in blood pressure.

Doctors link Lewy body dementia and Parkinson's disease dementia to the same underlying brain changes. The key difference lies in the timing of symptoms. In Lewy body dementia, problems with thinking, attention, and visual hallucinations appear before movement issues like slow movement, difficulty walking, and muscle stiffness, the Health and Human Services department explains. In Parkinson's disease dementia, movement symptoms arise first.

About 1.4 million Americans currently live with Lewy body dementia, making it the second most common form of dementia after Alzheimer's disease, according to Johns Hopkins and the Mayo Clinic. Risk factors include being male, being over age 60, and having a family history of Lewy body or Parkinson's disease dementia. Most diagnoses occur after age 50.

There is no known cure for the disease, though medications can manage symptoms. Cholinesterase inhibitors are used to improve alertness, thinking, and memory while reducing hallucinations. Medications typically prescribed for Parkinson's disease can also target muscle rigidity and other motor disorders associated with Lewy body dementia. The average life expectancy after diagnosis is up to eight years, depending on age, overall health, and symptom severity.