Diagnosing Dementia with Lewy Bodies

This is the second of three blogs about Lewy body dementia. You’ll find part 1 here.

Dementia with Lewy bodies (DLB) is a degenerating brain disease that causes dementia and symptoms of Parkinson’s disease. As I wrote in part one, it’s frequently misdiagnosed because it’s so little known. Also, it shows up with a wide variety of symptoms. Some are distinctive and some mimic other dementias. 

When primary care physicians screen for dementia, they are mostly looking for a decline in short-term memory—an early, prominent symptom of the most common dementia, Alzheimer’s.

In contrast, in DLB, the earliest cognitive change is a decline in executive function—that is, the ability to plan and carry out an action. Someone developing DLB will have trouble organizing, planning, reasoning, focusing their attention and doing things, like getting dressed, that need to be done in a certain sequence. Also impaired are visual abilities such as depth perception and eye-hand coordination, and to a lesser extent, memory. 

The challenge is that initially memory problems and these other problems in thinking look very similar. Later, they are more distinct.

At that point, you might see a woman with Alzheimer’s who can still drive her car but can’t find her way home. The procedure for operating the car is  in her long-term memory, which she can still access. Wayfinding depends on storing a short-term memory so it lasts long enough that she can use it, which she can no longer do. 

A man who has dementia with Lewy bodies can’t start his car in the first place, because he’s lost his grasp of the sequence of the steps he must take to start the car.

(These examples are based on cases in an excellent book, A Caregiver’s Guide to Lewy Body Dementia [2020], by Helen Buell Whitworth and James Whitworth.)

In their very late stages, the two diseases again look more alike. 

To make matters worse, there is growing evidence from autopsies that half of all DLB cases show evidence of Alzheimer’s pathology as well. Thus, half of all people with DLB may have symptoms of both.

In that case, does it matter which disease or diseases someone has?

Yes. It’s very important to know—and know early–if dementia with Lewy bodies is playing a role, because DLB makes people very sensitive to medications, including many that would be the drugs of choice for their most troubling symptoms.

Two of these symptoms can appear early in DLB, and both increase the chance that drugs dangerous for people with DLB will be used if a doctor has not made the correct diagnosis. 

One is rapid eye movement (REM) sleep disorder, named for the movements our eyes make while we dream. 

Normally, our muscles are temporarily paralyzed during REM sleep, to keep us from acting out our dreams. For reasons not fully understood, this paralysis sometimes doesn’t happen in diseases caused by Lewy bodies. When someone with DLB has a dream full of action, their thrashing arms and legs put them and their bed partner at risk of injury.

REM sleep disorder is not a part of Alzheimer’s. That makes it a red flag for DLB, even when it precedes, as it often does, any other symptoms.

Hallucinations are the second symptom that can show up early in dementia with Lewy bodies and that carry the risk of being treated inappropriately if DLB has not yet been diagnosed. Generally, the DLB hallucinator sees realistic but benign figures, like children or small animals, and isn’t frightened by them. But there is wide variation.

Millie, a 70-year-old woman, had early dementia with Lewy bodies. One day, when her daughter called, Millie told her, “Grandpa’s sitting in the blue chair in the living room. He’s been sitting there all day.”

“Do you mean Dad?” her daughter asked.

“No. Grandpa Freddy.”

“But that’s impossible. He’s been dead 60 years!” her daughter protested.

“Well, I can’t help that. There he is,” Millie calmly told her.

In contrast, if a person with Alzheimer’s develops hallucinations it will be much later in the disease, and they are not likely to be as benign.

Sometimes, dementia with Lewy bodies is mistaken for a psychiatric illness because it can cause anxiety, depression and agitation, as well as hallucinations and delusions. 

Before my friend’s mother, Suzy, was diagnosed with DLB, she was treated for anxiety and agitation with diazepam (Valium). It caused such deep sedation, everyone was afraid she might not come out of it. 

The doctor took her off diazepam, but when the sedation wore off, her agitation returned, along with disturbing hallucinations, so the doctor, still not realizing she might have dementia with Lewy bodies, gave her haldoperol (Haldol), one of the most dangerous drugs for anyone who has dementia with Lewy bodies. 

Suzy developed severely rigid muscles, and her thinking declined precipitously. Once off the haldoperol, she improved but was never again able to live independently.

Given the sometimes tragic consequences that can result from DLB not being diagnosed early enough, if you have reason to be concerned that you or someone you love may have it, there’s comfort in knowing that you can get an answer. 

Medicine has reached a consensus on the symptoms required to make a diagnosis. I will list the symptoms in order of their importance and then tell you where you can go to get an accurate diagnosis.

Besides dementia, which is the essential feature, at least two of these four core symptoms must be present:

• Fluctuating levels of attention and focus; spells of staring or unresponsiveness.
• Recurrent visual hallucinations—fully formed and realistic images. 
• REM sleep behavior disorder.
• Parkinsonism: slow movements, tremors at rest, rigid muscles.

Other symptoms common in DLB can support the diagnosis, such as sensitivity to medications, repeated falls, daytime sleepiness or a major change in mood—a formerly enthusiastic person becoming immobilized by apathy, for example. 

If the diagnosis remains in doubt, a type of brain scan called a DaTscan is sometimes used. It reveals the level of dopamine in the brain—a low level is characteristic of DBL. The results of the test are not definitive but are used as an adjunct to a physician’s assessment.

If this review of the important symptoms matches some of the symptoms you see in a family member, you need to find someone who can give you an accurate diagnosis.

When people move on from their primary physician to a neurologist, they commonly feel they’re going to a specialist who will have the answers. But Jason Karlawish, MD, co-director of the University of Pennsylvania’s Memory Clinic, says, “Finishing neurology training doesn’t make you an Alzheimer’s doctor.” I would add, much less a DLB doctor.

Neurology today is largely divided into subspecialties. For example, some neurologists concentrate on stroke, others on epilepsy.  For a diagnosis of dementia with Lewy bodies, you need a neurologist who specializes in dementia or in movement disorders.

The best place to start looking for a specialist is the Lewy Body Dementia Association website. There you will find information about their Research Centers of Excellence (RCOE). By all means, go to one of them if you can!

There are 20 such centers across the United States, and they have proven expertise in the diagnosis and care of people with DLB. Even if there isn’t a center within reasonable reach, any RCOE or the LBDA itself may be able to help you find a qualified neurologist near you. 

Then the bigger challenge begins: living with dementia with Lewy bodies—as a diagnosed person or as a caregiver. If you know the symptoms and the behavior that stems from DLB, you will be better prepared to live this experience with compassion and grace. 

That will be the topic of my next blog, the last in this three-part series.