Home > Information and Support > Information leaflets > A Guide To Lewy body dementia
Lewy body dementia (LBD) is one of several types of dementia. It is a complex, challenging and common brain disorder which affects many parts of the brain in ways that scientists are still trying to understand. As with other forms of dementia, its symptoms make it difficult for the patient to do everyday tasks that once came easily.
Although less well-known than Alzheimer’s and Parkinson’s diseases, Lewy body dementia is not a rare disorder. It is often described as ‘the most common disease you’ve never heard of’, yet it accounts for about 15-20 per cent of all people with dementia. Approximately 125,000 people in the United Kingdom live with its disabling effects upon their ability to think and act. Taking into account families and other carers of those living with the disease, it probably affects the lives of at least half a million people in the UK.
As researchers seek better ways to treat Lewy body dementia– and ultimately to find a cure – people with Lewy body dementia and their families often struggle with delay in receiving an accurate diagnosis, accessing the best advice about supportive treatments and managing the disease at home.
This guide mainly uses the term Lewy body dementia. You may sometimes see other terms used as there are two sub-types of Lewy body dementia: dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD). They are also sometimes collectively referred to as Lewy body disease.
The difference between them is essentially the timing of some of the major symptoms, which is explained on pages 10 and 13. In this guide the term Lewy body dementia (LBD) will be used unless something pertains particularly to either DLB or PDD.
This guide is intended to help people with Lewy body dementia, their families and carers and healthcare professionals to learn more about the disease and the impact it has. It explains what is known about the different types of Lewy body dementia and how they are diagnosed. Most importantly, it describes how to treat and manage this difficult disease, with practical advice both for people with Lewy body dementia, their families and carers.
The Lewy Body Society, established in June 2006 in the UK, was the first charity in Europe exclusively concerned with Lewy body dementia. Our mission is to fund clinical research to improve the diagnosis and treatment of the disease. We also raise awareness of Lewy body dementia amongst the general public and those in the medical professions and decision-making positions, and we provide information resources for people with dementia and carers.
This 2024 edition of the guide is a revised version of one of our most popular resources. It is available to freely download from our website
and those who require hard copies should contact us. We would like to thank everyone who has donated to the Lewy Body Society
or completed fundraising events. We have such a strong network of supporters, many of whom have been personally affected by the
disease, and by enabling us to produce this guide they are directly helping others.
You can keep up to date with our work by visiting our website at www.lewybody.org, following us on Facebook www.facebook.com/lewybodysociety, twitter at www.twitter.com/lbsorg, Instagram www.instagram.com/lewybodysociety or search for us on YouTube to watch information videos.
Dementia is defined as a loss of thinking abilities sufficient to interfere with a person’s capacity to perform daily activities such as household tasks, personal care and handling finances. How we support people living with dementia is a growing issue in society. It is estimated that over 1 million people in the UK will have dementia by 2025 and this will increase to 1.6 million by 2040.*
Lewy body dementia (LBD) is caused by abnormal deposits of a protein called alpha-synuclein in the brain. These deposits are called Lewy bodies, after Dr Friedrich Lewy, who first discovered them under the microscope in 1912. They affect brain cell function, leading to problems with thinking, movement, behaviour and mood.
LBD is believed to be the second most common cause of age-related dementia after Alzheimer’s disease, which accounts for approximately 60 per cent of all diagnoses of dementia. The common perception that Alzheimer’s is the only type of dementia is therefore far from correct. Dementia includes a range of neurodegenerative diseases including Lewy body dementia, vascular dementia, fronto-temporal dementia (Pick’s disease) and the dementia associated with Parkinson’s disease. Dementias can also be caused by a stroke, vitamin deficiency, alcohol abuse, traumatic brain injury or other rarer disorders. Early LBD symptoms are often confused with similar symptoms typical of other dementias.
LBD typically begins around the age of 60 or older, although sometimes younger people develop it. It appears to affect slightly more men than women.
It is a progressive disease, which means that symptoms start slowly and worsen over time. The average time between diagnosis and death is 5-7 years but can range from 2-20 years. How quickly the disease progresses varies greatly from person to person and depends on a number of factors such as overall health, age and severity of symptoms.
In the early stages of LBD, often before a diagnosis is made, symptoms are usually mild and people may be able to function fairly normally. As the disease advances, people with LBD require increasing amounts of support as their ability to think and move declines. In the later stages of the disease people become very dependent on others for assistance with dressing, eating, moving and general care. Towards the end of life they may need to be cared for in bed.
Some LBD symptoms may respond to treatments for a period of time. A cure for the disease has not yet been found. Research has improved understanding of this complicated condition and advances in science will hopefully lead to better diagnosis, improved care and new treatments.
Lewy bodies are made of a protein called alpha-synuclein. In a healthy brain alpha-synuclein has a number of important functions, especially at the synapses (nerve cells) where brain cells communicate with each other. In LBD this protein forms into clumps inside of neurones, making them less effective. Eventually the cells die. Lewy bodies also affect certain chemicals which regulate brain function. The result is widespread damage and decline in the brain’s proper functioning.
The areas of the brain affected by LBD are:
• the cerebral cortex, which controls many functions, including information processing, perception, thought and language;
• the limbic cortex, which has a major role in controlling emotions and behaviour;
• the hippocampus, which is essential to the formation of new memories;
• the midbrain, including the substantia nigra, which is involved in movement;
• parts of the brain stem important in regulating sleep and maintaining alertness;
• regions in the brain important to recognising smells (olfactory pathways).
Lewy bodies can also form in nerve cells outside the brain, in organs like the heart, stomach, bladder and bowel. This can give rise to symptoms that may not be immediately recognised as part of LBD, like feeling lightheaded or dizzy, drops in blood pressure, constipation and troubles with passing urine.
As mentioned in the introduction, there are two types of Lewy body dementia: dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD). Both variants typically cause both movement problems and cognitive symptoms. The distinction, and therefore which diagnosis a person receives, depends on the order in which symptoms are observed and how closely together. Over time, people with DLB and PDD tend to develop similar symptoms.
Dementia with Lewy bodies (DLB) initially presents as a cognitive condition. If someone does not have movement problems, or develops them around the same time as developing cognitive symptoms (within a year), they are diagnosed with DLB.
DLB may initially appear as a decline in cognitive skills which resembles Alzheimer’s disease. Over time, however, distinctive symptoms develop which suggest DLB. These may include:
• visual hallucinations;
• fluctuations in cognitive ability, attention and alertness;
• slowed movement, difficulty walking, a tremor (shake) or rigidity (parkinsonism);
• sensitivity to medications used to treat hallucinations;
• Rapid Eye Movement (REM) sleep behaviour disorder;
• difficulties with visual perception (how we see things);
• more difficulty with executive function than memory. Executive function means performing complex mental activities such as multitasking, problem solving, spatial awareness and analytical thinking.
Parkinson’s disease is characterised as a movement disorder, with symptoms such as slowed movement, muscle stiffness, tremor or a shuffling walk. Cognitive symptoms of dementia and changes in mood and behaviour may arise later.
If someone has movement problems caused by Parkinson’s disease for more than year before cognitive symptoms develop, the person is considered to have Parkinson’s disease dementia.
Not all people with Parkinson’s disease develop dementia and it is difficult to predict who will. Being diagnosed with Parkinson’s late in life, however, is a risk factor for PDD.
The most common form of dementia, affecting around 60 per cent of people, is Alzheimer’s disease. The main differences between it and Lewy body dementia are that people with Alzheimer’s disease are much more likely to have memory impairment and typically have a less severe loss of executive function in the early stages of the disease.
In contrast, people with LBD are more likely to have psychiatric symptoms, especially hallucinations, the parkinsonian symptoms outlined above and fluctuations in cognitive function.
The precise cause of LBD is still unknown but scientists are learning more about its biology and genetics. They know, for example, that an accumulation of Lewy bodies is associated with a loss of certain neurones in the brain that produce two vital neurotransmitters (chemicals that act as messengers between brain cells). One of these messengers, acetylcholine, is essential for memory and learning. The other, dopamine, plays an important role in regulating behaviour, cognition, motivation, movement, sleep and mood.
Known risk factors include:
Age
Research has shown that age is the greatest risk factor. Most people who develop LBD are over the age of 60.
Diseases and health conditions
Parkinson’s disease and REM sleep disorders are linked to a higher risk of LBD.
Genetics
Whilst having a family member with LBD may increase a person’s risk, LBD is not ‘inherited’ directly through a particular gene. At this time a genetic test to predict accurately a predisposition to LBD has not been developed but future genetic research could reveal more information about causes and risks.
Lifestyle
No lifestyle factor has yet been specifically proven to increase the risk of developing LBD. Some studies, however, suggest that a lifestyle which includes regular exercise, mental stimulation and a healthy diet can reduce the risk of age-related dementia.
People with LBD may not have every symptom discussed in this guide and the severity of the symptoms varies from person to person. Any sudden or major change in functional ability or behaviour should be discussed with a doctor.
The most common symptoms include changes in these areas:
People with LBD may experience significant changes in the autonomic nervous system, which regulates the involuntary actions of the heart, muscles and glands.
The person may have:
• frequent variations of body temperature;
• fluctuating and/or abnormal blood pressure;
• dizziness;
• fainting;
• sensitivity to heat and cold;
• frequent falls;
• sexual dysfunction;
• constipation;
• impaired sense of smell.
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