Angela struggles daily to live with Parkinson's disease. Amid the tremors, a lesser-known aspect of the illness has emerged: memory impairment.

On good days, Angela goes out with her nurse for a short walk around the block of her New Jersey home. Sometimes, she might even show you a little dance step or recite all the stars' names from an old film.

Thirteen years ago, Angela was diagnosed with Parkinson's disease. She's now 76, and the disease has since taken its slow but progressive course. Most people are aware of the disease's most distinguishing characteristics-tremors, difficulty initiating movements. For Angela, just walking across a room or swallowing can sometimes be an ordeal. But there's also a lesser known side effect of Parkinson's, one that makes the disease debilitating not only physically, but also mentally: memory loss.

Loss of dopamine

Nearly one million people in the United States suffer from Parkinson's. In fact, it affects about one in every 250 people over 40 and about one in every 100 people over 65 years old. Parkinson's occurs when neurons in a region of the brain called the substantia nigra degenerate and stop producing a chemical called dopamine, which transmits signals between brain cells.

As a result, Angela experiences dyskinesia, the abnormal involuntary movements of the body associated with Parkinson's. "People look at me and they think I'm crazy shaking all over. It's terrible. I don't wish it on a dog," she says.

Of course when just walking across a room is an immediate concern, worrying about a slight loss of memory may seem trivial. But the memory problems connected with Parkinson's can interfere with daily life-and they can, sometimes, evolve into dementia, the global loss of one's intellectual capacity.

Slowness of thought

Angela's memory impairment reveals itself in subtle ways. In conversation, she is at a loss for a certain word-the so-called "tip-of-the-tongue" syndrome common to people with impaired memory. Her husband, Pat, helps by filling in the word. Cognitive difficulties associated with Parkinson's, including memory impairment, are usually characterized by slowness of thought.

Some recent research on Parkinson's has explored the idea that patients who have motor impairment and thus move slowly and have smaller movements, may also think slowly and have smaller thoughts. Angela's physician, Ronald Schwartz, MD, a neurologist and Director of the Memory and Cognitive Disorders Program at Saint Barnabas Medical Center in West Orange, New Jersey, has been studying this phenomenon. He's found that as people with Parkinson's get older, they have more trouble estimating distances and how long a certain action will take.

Effects on thinking and memory

Sometimes the slow thinking escalates to dementia. About 30 percent of Parkinson's patients will become demented in the later stages of the disease. The type of dementia most associated with the disease is known as subcortical dementia, which affects attention, motivation, and emotions. Patients may be confused, disoriented, agitated, or moody. As the disease progresses, memory problems also arise, and some individuals may develop symptoms similar to those of Alzheimer's disease. Although changes in memory and thinking can appear at any stage in the progression of the disease, the onset of these symptoms is usually gradual and is more common in those that have had the disease for many years-such as Angela.

Those changes are already apparent in conversations with Angela. She sometimes seems unfocused and distracted, jumping from one topic to another. Conversation skips from reading, to dancing at a wedding, to how she first noticed the disease, to her first doctor, to her husband, to heartburn, constipation, and protein shakes. "When we're talking about one thing, she's talking about another thing," says Pat, her husband. "When I'm talking about potatoes, she'll say tomatoes."

This, says Dr. Schwartz, is typical of the patients he has observed. "The cognitive problems that are associated with Parkinson's disease are, amongst other things besides memory impairment, trouble focusing attention, trouble shifting attention from one set to another set," he explains. "They don't have the mental flexibility."

Yet Angela has no trouble remembering old, deeply embedded memories of her dance steps, the movie stars of her youth, or good friends' names. She knows the steps of dances from the cha-cha to the mashed potato-and when she's in the mood, she'll do them. But she has more trouble with short-term memory, or the memory of recent events-such as conversations with her husband. "I don't pay attention to things," she says. "I can't concentrate on what he's saying."

Complicated treatment

Five times a day, or every four hours beginning at 4 a.m., Angela takes an assortment of pills to gain some relief from her tremors, to help her sleep, and to help her deal with anxiety and depression. Because of the amount of medications Angela is taking-a total of six daily prescriptions-Dr. Schwartz is reluctant to add any new medications to address her memory problems. "It would complicate her treatment and may even counteract the effects of her dopamine therapy, Dr. Schwartz says.

"Parkinson's is a particularly difficult disease to manage medically," he explains. "As the disease progresses, the response to medications becomes somewhat unpredictable. Too little and they aren't able to move at all; too much and they are dyskinetic." That balance can be an extremely fine line and can vary day to day.

Angela's fervent desire was to be able to attend her granddaughter's wedding this past summer -- and hopefully dance, too. "Two years ago, she danced all night at our nephew's wedding," her husband proudly notes. "I used to love dancing," she says. "I wish I can make it to my granddaughter's wedding. I'm gonna try." And she did.

Further Reading:

• "Understanding Parkinson's Disease," by M. Youdim and P. Riederer, in Scientific American, January 1997, pp. 52-59.
• "Cognitive deficits in Parkinson's disease," by B. Dubois and B. Pillon, in Journal of Neurology, 1997, vol. 244, pp. 2-8.

On the Internet, many Parkinson's related foundations maintain helpful websites. A good place to get started is at the government's NIH website, which contains information and links to other resources: http://www.nlm.nih.gov/medlineplus/parkinsonsdisease.html.