What Is Lewy Body Dementia? A Guide to Symptoms, Diagnosis, and Care

Don Kent was a practicing lawyer when the people around him started to notice he wasn’t quite himself. His sense of taste changed in ways he couldn’t explain. His personality shifted, abruptly and out of character. And his memory, oddly, seemed fine.

 

It took six neurologists to get it wrong before Kent finally got an answer at the Mayo Clinic.

 

“I never got asked about my sleep until I got to the Mayo Clinic,” Kent told Being Patient. “For me it was a loss of a sense of taste and a rather abrupt personality change.”

 

Kent has Lewy body dementia (LBD) — a disease that affects an estimated 1.4 million Americans, making it the second most common type of dementia after Alzheimer’s.  His path to a diagnosis is not unusual. LBD is among the most frequently misdiagnosed dementias, in part because its symptoms can overlap with those of Alzheimer’s and Parkinson’s disease.

 

Standard cognitive screenings can further complicate diagnosis because they often emphasize memory impairment, which may not be prominent in the early stages of LBD. In Kent’s case, memory loss was not what raised concern. “My memory was fine,” he said.

 

What is Lewy body dementia?

Lewy body dementia is characterized by Lewy bodies, abnormal clumps containing a protein called alpha-synuclein that accumulate inside nerve cells in the brain. Although researchers still do not fully understand what causes LBD, these deposits are associated with the dysfunction and loss of neurons in brain regions involved in thinking, movement, behavior, sleep, and other functions. LBD is also associated with disruptions in acetylcholine and dopamine, chemical messengers involved in cognition and movement.

Estimates of how common LBD is vary considerably, in part because the disease is frequently missed or misdiagnosed. Some studies have estimated that it may account for up to 20 to 30 percent of dementia cases, although population-based studies have generally produced lower estimates.

 

LBD can also overlap biologically with Alzheimer’s disease. Autopsy studies have found Alzheimer’s-related amyloid plaques and tau tangles in a substantial proportion of people with LBD. That overlapping pathology is one reason the diseases can be difficult to distinguish clinically.

How is Lewy body dementia different from Alzheimer’s?

Lewy body dementia and Alzheimer’s can share some symptoms, but they often affect people differently, particularly early in the disease course. Memory loss is a hallmark of Alzheimer’s, while people with LBD may initially have greater problems with attention, executive function, visual-spatial skills, movement, sleep, or perception.

 

People with LBD may experience visual hallucinations, REM sleep behavior disorder, and Parkinson’s-like movement symptoms such as muscle rigidity, tremor, slowed movement, and balance problems. That combination is less typical of early Alzheimer’s. Recurrent visual hallucinations, especially when they appear early, can be an important clue that points clinicians toward LBD.

 

The diseases are also associated with different abnormal proteins in the brain. LBD is characterized by deposits of alpha-synuclein known as Lewy bodies, while Alzheimer’s is defined by the accumulation of amyloid plaques and tau tangles, along with other changes in the brain. Because LBD can affect cognition, movement, sleep, behavior, and autonomic function at the same time, it can have a substantial impact on day-to-day functioning as the disease progresses.

Two types of Lewy body dementia

Lewy body dementia is an umbrella term that includes two closely related diagnoses: dementia with Lewy bodies and Parkinson’s disease dementia. Doctors distinguish between them largely based on when cognitive symptoms develop in relation to movement problems. 

Parkinson’s disease dementia develops in people with established Parkinson’s disease. Movement symptoms — such as slowed movement, muscle stiffness, tremor, and problems with balance or walking — come first, while significant cognitive decline develops later. Older research has suggested that as many as 80 percent of people with Parkinson’s may eventually develop dementia, although newer studies indicate the risk may be lower or develop over a longer period than previously thought.

Dementia with Lewy bodies is diagnosed when cognitive decline begins before or around the same time as Parkinsonian movement symptoms. Early features can include problems with attention and visual-spatial abilities, fluctuations in alertness, visual hallucinations, REM sleep behavior disorder, and Parkinsonism.

The distinction between the two conditions is not always clear-cut. As the diseases progress, their symptoms and underlying brain changes can become very similar, and clinicians often view them as closely related conditions on the same disease spectrum.

What are the symptoms of Lewy body dementia?

LBD can affect cognition, movement, sleep, mood, behavior, and automatic body functions, which is part of what can make the disease difficult to recognize. Cognitive symptoms can include fluctuations in attention and alertness, problems with executive function and visual-spatial abilities, and recurring visual hallucinations. Memory problems can also develop, though they may be less prominent early in the disease than they typically are in Alzheimer’s.

Mood and behavioral changes can include apathy, agitation, depression, delusions, and paranoia. Movement symptoms can resemble Parkinson’s disease, including slowed movement, muscle rigidity, tremor, balance problems, and a shuffling gait.

Sleep problems are also common. People with LBD may experience insomnia, excessive daytime sleepiness, and REM sleep behavior disorder, in which a person physically acts out dreams while asleep. LBD can also disrupt the autonomic nervous system, leading to problems regulating blood pressure, fainting, constipation, and urinary incontinence.

Kent’s earliest signs were not memory lapses but an abrupt personality change and what he initially experienced as a loss of taste, but later came to understand as a “taste hallucination.” Visual hallucinations developed later. He also experienced severe depression, which his physician told him was connected to his illness: “Your depression is not causing your illness, your illness is causing your depression.”

How is Lewy body dementia diagnosed?

There is no single test that can definitively diagnose LBD in a living person. Instead, doctors rely on a detailed medical history, symptoms, neurological examination, and, when needed, imaging or other tests.

“The most important thing is to talk carefully with a patient and carer who knows the patient and discuss what symptoms they have experienced,” Dag Aarsland, a researcher who studies LBD and Parkinson’s disease at King’s College London, told Being Patient.

Doctors typically look for four core features: fluctuating attention and alertness, recurring visual hallucinations, REM sleep behavior disorder, and Parkinsonian movement symptoms such as slowed movement, stiffness, or tremor. Under diagnostic criteria developed by the Dementia with Lewy Bodies Consortium, two or more core features can support a diagnosis of probable Dementia with Lewy bodies. One core feature combined with an indicative biomarker can also qualify as probable Dementia with Lewy bodies.

Tests can provide additional evidence. Dopamine transporter scans, MIBG heart imaging, and sleep studies can serve as indicative biomarkers, while MRI or CT scans, FDG-PET imaging, and EEG recordings can provide supportive clues.

Researchers are also developing tests that detect abnormal alpha-synuclein in cerebrospinal fluid and skin. These emerging biomarkers may eventually make diagnosis earlier and more objective, but they are not yet a standalone definitive test for LBD.

Early hallucinations can be an especially important clue. “Hallucinations in a person with very early dementia or even before dementia should make doctors suspicious that the patient does not have Alzheimer’s disease, but Lewy body disease,” Aarsland said.

Getting the diagnosis right also affects treatment. People with LBD can be unusually sensitive to certain antipsychotic medications, which can severely worsen symptoms and, in some cases, cause life-threatening reactions.

Progression of Lewy body dementia

LBD is progressive, meaning symptoms worsen over time, but there is no defined set of stages. The pace and order of symptoms can vary considerably from person to person.

Early symptoms may be relatively mild and can include changes in attention, visual-spatial abilities, sleep, mood, or movement. Memory problems may not be obvious at first, but often become more apparent as the disease progresses.

Over time, problems with thinking and movement typically become more pronounced, and hallucinations, sleep disturbances, behavioral changes, and autonomic symptoms may also worsen. In later stages, people with LBD often need increasing help with daily activities and may eventually depend entirely on others for care.

How is Lewy body dementia treated?

There are currently no FDA-approved treatments that can slow, stop, or reverse LBD. Treatment instead focuses on managing symptoms.

Cholinesterase inhibitors such as donepezil, rivastigmine, and galantamine may help with cognitive symptoms, while carbidopa-levodopa can sometimes improve Parkinsonian movement problems. Melatonin is often used for REM sleep behavior disorder.

Medication choice requires particular care. People with LBD can be highly sensitive to antipsychotic drugs, which may severely worsen movement and cognitive symptoms and, in some cases, cause life-threatening reactions.

Physical, occupational, and speech therapy can also help people manage symptoms and maintain independence for as long as possible.

Even without a cure, an accurate diagnosis can still make a difference — helping patients avoid potentially harmful medications, get appropriate care, and connect with specialists who understand the disease.