Dementia With Lewy Bodies May Be More Common Than We Think

Dementia with Lewy bodies — a disease characterized by faster progression and greater functional decline than Alzheimer’s disease — was confirmed as a predominantly late-onset dementia with incidence rising sharply with age, a systematic review and meta-analysis showed.

Across 12 population-based studies, the pooled incidence was 46.85 per 100,000 person-years (95% CI 23.78-92.30) for people ages 65 and older, and the pooled prevalence was 352.26 per 100,000 population (95% CI 112.25-1,099.79), reported Daniele Urso, MD, MPH, of the University of Bari Aldo Moro in Italy, and co-authors in JAMA Neurology.

In people younger than 65, the pooled incidence was 0.34 per 100,000 person-years (95% CI 0.14-0.83) and the prevalence was 2.52 per 100,000 population (95% CI 1.43-4.44).

Pooled crude incidence across all ages was 4.79 (95% CI 3.90-5.88). Incidence was higher in men (5.45) than in women (4.32).

The findings show that clinically diagnosed dementia with Lewy bodies was uncommon, likely reflecting underdiagnosis and diagnostic insensitivity, the researchers observed.

“Dementia with Lewy bodies is considered the second most common form of degenerative dementia in older adults after Alzheimer’s disease, but we still know surprisingly little about how common it is at the population level,” Urso said.

“Our study represents one of the first attempts to systematically meta-analyze population-based estimates of the incidence and prevalence of dementia with Lewy bodies,” he told MedPage Today.

Population-based studies provide the most reliable evidence to help understand the real-world burden of the disease, Urso noted. “Reliable estimates are also essential for healthcare planning,” he said. “Dementia with Lewy bodies often requires a different clinical approach compared with other dementias, because patients may present with a complex combination of cognitive, motor, psychiatric, sleep, and autonomic symptoms.”

Dementia with Lewy bodies is characterized by abnormal accumulation of alpha-synuclein into Lewy bodies and Lewy neurites that involve both cortical and subcortical regions. It is marked by progressive cognitive decline along with fluctuating cognition, recurrent visual hallucinations, REM sleep behavior disorder, and spontaneous parkinsonism, frequently accompanied by psychiatric symptoms and autonomic dysfunction.

Diagnosing dementia with Lewy bodies can be difficult because of its substantial overlap with other neurodegenerative disorders. That uncertainty can be particularly distressing for patients and families as Susan Schneider Williams described in an essay in Neurology about the experience of her husband, actor and comedian Robin Williams, who developed Lewy body disease and subsequently died by suicide.

“Lewy body dementia is more common than many people realize; however, it is often overlooked or mistaken for Alzheimer’s or Parkinson’s disease,” noted Michael Okun, MD, of the University of Florida Fixel Institute in Gainesville, who wasn’t involved with the study. “Awareness matters because recognizing the diagnosis early can change care, safety, and quality of life for families,” he told MedPage Today.

“This study reminds us that Lewy body dementia is not rare in older adults, and the numbers likely underestimate the true burden because many cases are missed in everyday practice,” Okun added. “We need better recognition, better tools, and more conversations about symptoms like hallucinations, dream enactment, and fluctuating thinking.”

Urso and co-authors systematically searched PubMed, Embase, and Scopus from inception to October 2024 for population-based studies that reported the incidence or prevalence of dementia with Lewy bodies based on validated diagnostic criteria.

They identified 16 studies and used 12 in the meta-analysis. The studies had considerable heterogeneity (between-study I² was 85% or higher), which may partly reflect inherent diagnostic challenges, Urso and colleagues noted.

“Notably, the pooled incidence of dementia with Lewy bodies was higher than population-based incidence estimates reported for other uncommon neurodegenerative disorders such as frontotemporal dementia (2.28 per 100,000 person-years), amyotrophic lateral sclerosis (1.59 per 100,000 person-years), and atypical parkinsonian syndromes, including progressive supranuclear palsy (0.81 per 100,000 person-years) and corticobasal syndrome (0.28 per 100,000 person-years),” they wrote.

The meta-analysis was limited by the small number of studies and high heterogeneity, the researchers acknowledged. Changes in diagnostic criteria over time may have influenced results, they added.

“Our findings also show that the current evidence base remains limited,” Urso said. “There are relatively few population-based studies, and most come from high-income countries. This means that we need more studies from different regions of the world, especially in underrepresented populations, to understand the true global burden of dementia with Lewy bodies.”