For more information, read our print-friendly, downloadable brochure on Lewy body dementia.
Dementia with Lewy bodies occurs because of abnormal deposits of a protein called alpha-synuclein that develop inside the brain’s nerve cells. The deposits are called ‘Lewy bodies’ after the scientist who first described them, Dr. Freidrich Heinrich Lewy. Dementia with Lewy bodies accounts for between 5 and 15% of all dementia cases.
These protein deposits – or Lewy bodies – typically affect the areas of the brain that involve thinking and movement. The built-up mass of Lewy bodies block messages between brain cells, leading to dementia.
Lewy bodies are also found in Parkinson's disease. When Lewy bodies first appear in the part of the brain responsible for thinking, the term Dementia with Lewy bodies is used. When Lewy bodies first appear in the part of the brain responsible for movement, the term Parkinson's disease dementia is used.
Dementia with Lewy bodies can occur together with Alzheimer’s disease or Parkinson’s disease – this is known as "mixed dementia".
Dementia with Lewy bodies can also be referred to as:
- Lewy body dementia or
- Lewy body disease.
Dementia with Lewy bodies can cause symptoms that are similar to both Alzheimer’s disease and Parkinson’s disease.
- People living with Dementia with Lewy bodies commonly experience a progressive loss of memory, language, reasoning and other higher cognitive functions, like the ability to calculate numbers.
- Unlike Alzheimer's disease, memory loss may not occur at the early stages of the disease. Difficulties with planning, organizing, and marked fluctuations in attention and alertness may be some of the first symptoms. The person may also experience changes to visual-spatial perception in the early stages.
- Other symptoms of Dementia with Lewy bodies can include:
- Difficulty with short-term memory, finding the right words to use, or maintaining a train of thought,
- Depression and anxiety,
- Changes in sleeping patterns, including feeling tired during the day and alert throughout the night,
- Visual hallucinations and seeing things that are not real (hallucinations often include people, children, and animals who are not present),
- Mistakes in perception of objects or textures (for example, seeing faces in a carpet pattern),
- Motor symptoms of Parkinson's disease, which may include stiffness of muscles, tremors (shaking), stooped posture or slow, shuffling movements and
- Acting out one's dream. This may occur years before the development of other symptoms.
No single test can diagnose Dementia with Lewy bodies.
Doctors typically diagnose Dementia with Lewy bodies by eliminating other diseases and conditions that cause similar symptoms.
Common assessments can include a neurological exam to assess:
- The way a person walks (referred to as a ‘gait analysis’),
- Posture and
- How rigid or stiff the person’s body is.
Other measures to assist in a diagnosis include:
- Obtaining a detailed medical history,
- Brain imaging (e.g. MRI) and
- Physical and neuropsychological testing.
Doctors do not know what causes Dementia with Lewy bodies.
However, Lewy bodies have a protein that is also seen in Parkinson’s disease, suggesting the conditions may be linked in some way.
If a family member has Dementia with Lewy bodies, you may have a higher risk of developing the disease. Dementia with Lewy bodies is more common in men than in women.
Unfortunately, there is currently no cure for Dementia with Lewy bodies. However, doctors can prescribe medications to treat some of the symptoms that a person will experience, like unpleasant hallucinations.
The medications used to treat Alzheimer’s disease called cholinesterase inhibitors and can improve alertness and cognition in some people with Dementia with Lewy bodies.
However, because Dementia with Lewy bodies has so many different features and symptoms, such as symptoms associated with Parkinson's and Alzheimer's disease, using medication to treat one symptom may worsen another. One way to avoid or prevent this issue is to treat symptoms in priority based on their severity.
Therapeutic strategies are also helping people living with the disease. For example, therapeutic techniques like physical activity and music are being used as viable and useful treatments. Research shows that the quality of life of people with dementia and of their caregivers is significantly improved by activities that emphasize their strengths and abilities.
More useful links and resources
Lewy body dementia. Alzheimer Society of Canada. This downloadable brochure contains additional details on Lewy body dementia beyond the content of this website page.
The Lewy Body Dementia Association (LBDA). The LBDA offers information, supports and resources for people living with Lewy body dementia.
Lewy body dementia: Information for patients, families and professionals. National Institutes of Health (NIH), 2018. This U.S.-focused comprehensive resource covers symptoms, risk factors, management techniques, and advice for carers and family members.
The spectrum of Lewy body disease: Dementia with Lewy bodies and Parkinson’s disease dementia. brainXchange in partnership with the Alzheimer Society of Canada and the Canadian Consortium on Neurodegeneration in Aging (CCNA), 2012. This webinar covers neurodegenerative disorders characterized by accumulation of Lewy bodies in brain cells. Presented by Mario Masellis, MSc, MD, PhD, FRCPC, Clinician Scientist and Associate Professor, Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre, University of Toronto.
An update on Lewy body spectrum disorders. brainXchange in partnership with the Alzheimer Society of Canada and the Canadian Consortium on Neurodegeneration in Aging (CCNA), 2020. This is an update on the 2012 webinar on Lewy body disease. Presented by Mario Masellis, MSc, MD, PhD, FRCPC, Clinician Scientist and Associate Professor, Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre, University of Toronto.