Behavioral And Neuropsychiatric Features
In DLB, visual hallucinations tend to be well-formed, detailed, most commonly involving people , animals, body parts, and machines. Auditory hallucinations can occur in a subset of people with visual hallucinations. Visual hallucinations are typically present early in the course of the disease and do not resolve with disease progression. In an analysis of autopsy-confirmed cases, hallucinations and delusions were more frequent with LB pathology than AD at the time of the initial clinical evaluation . This was also true for those cases with mixed DLB and AD pathology relative to AD alone. The occurrence of visual hallucinations in the first 4 years after dementia onset has a positive and negative predictive value for DLB of 81% and 79%, respectively . Visual hallucinations are linked to cholinergic depletion in the temporal cortex and the basal forebrain and may predict a good response to cholinesterase inhibitors . Delusions occur in more than half of DLB patients at first presentation and in just over two-thirds at some point in their illness. Delusions tend to be more common in DLB than in PDD or AD. Paranoid, Caprgras and phantom boarder are among the most common content of the delusions. Misidentification syndromes are particularly prevalent in DLB occurring in up to 40% of patients, compared to 10% in AD .
Where Can I Get More Information
For more information on neurological disorders or research programs funded by the National Institute of Neurological Disorders and Stroke, contact the Institute’s Brain Resources and Information Network at:
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NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.
All NINDS-prepared information is in the public domain and may be freely copied. Credit to the NINDS or the NIH is appreciated.
Linkage Disequilibrium Score Regression
Single-trait LDSC estimates for GWASLBD, GWASAD, and GWASPD were shown in Additional file : Table S2. The estimates of liability-scale SNP heritability were 0.1122 for LBD, 0.0105 for AD, and 0.0259 for PD. The mean 2 statistics were all greater than 1.02, the genomic inflation factors were all less than 1.1, and the LDSC intercepts were all close to 1. All these results indicated that the inflation of test statistics was probably caused by polygenicity rather than potential population stratification.
Pairwise LDSC analysis found positive genome-wide genetic correlations between LBD and AD , between LBD and PD , and between AD and PD .
Table 1 Pairwise genetic correlation among LBD, AD, and PD using LDSC
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How Is Lewy Body Dementia Related To Alzheimers Disease And Parkinsons Disease
Dementia with Lewy bodies and Parkinsons disease dementia are two related clinical disorders that make up the general broader category of Lewy body dementia. Sometimes, providers first diagnose LBD as Parkinsons disease or Alzheimers disease based on its symptoms.
- Parkinsons disease dementia : Some people are diagnosed with Parkinsons disease if they first have symptoms of a movement disorder typical to Parkinsons. But their diagnosis is changed to PDD if dementia symptoms develop over the years.
- Alzheimers disease : Some people who have a memory or cognitive disorder are diagnosed with AD. But other distinctive symptoms may suggest co-existing dementia with Lewy bodies. Distinctive symptoms of LBD include changes in attention, alertness and cognitive ability movement issues visual hallucinations and more.
What Does Lewy Body Dementia Look Like
Lewy body dementia affects a persons ability to think and process information and it can negatively impact memory and alter personality. Though it shares aspects of other forms of dementia, there are distinct hallmarks of LBD. Lewy body dementia symptoms include:
- Fluctuating attention/alertness: These shifts can last hours or go on for days. The person may stare into space, appear lethargic or drowsy, and have hard-to-understand speech, appearing a lot like delirium. At other times, the person may have much more clarity of thought.
- Visual hallucinations: Often, these are very detailed hallucinations and visions of people or animals, and they can recur.
- Movement disorders: Parkinsons-like movement issues, such as muscle rigidity, tremors, falls, or a shuffling gait or way of walking, may occur.
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Types Of Lewy Body Dementia
It’s important to know which type of LBD a person has, both to tailor treatment to particular symptoms and to understand how the disease will likely progress. Clinicians and researchers use the “one-year rule” to help make a diagnosis. If cognitive symptoms appear at the same time as or at least a year before movement problems, the diagnosis is dementia with Lewy bodies. If cognitive problems develop more than a year after the onset of movement problems, the diagnosis is Parkinson’s disease dementia.
Regardless of the initial symptoms, over time, people with either type of LBD often develop similar symptoms, due to the presence of Lewy bodies in the brain. But there are some differences. For example, dementia with Lewy bodies may progress more quickly than Parkinson’s disease dementia.
Dementia And Family Planning
If someone is known to carry a single-gene change that causes dementia, this may affect their plans to start a family. This is because there is a 1 in 2 chance of inheriting the same changed gene for any children they have.
In these cases, it is possible to try an approach called pre-implantation genetic diagnosis .
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Studies In Familial Forms Of Dlb
Although not particularly common, several DLB families have been studied, but these have failed to shed much light on the genetics of the disease. Only a small proportion of patients within these families underwent genetic analysis, and if performed, it was usually minimal with very few cases assessed at the exome or genome levels. As mentioned above, variation in SNCA sequence or dosage has been identified in families as the cause of mixed PD and DLB phenotypes. Some DLB patients have a family history of neurodegenerative disease, but not necessarily of DLB, with family members being diagnosed with AD or PD. Alzheimer families with mutations in APP, PSEN1 and PSEN2 have been described with phenotypes of mixed parkinsonism and dementia suggestive of DLB , and extensive Lewy body pathology has also been found in Alzheimers families with these mutations , suggestive of a possible mechanistic link. Indeed, DLB cases frequently present A pathology at autopsy , and it has been suggested that A accumulation can trigger Lewy body disease . A recent review by Vergouw and colleagues provides a summary of familial studies in DLB. The most promising study to identify a novel DLB gene relied on linkage analysis in a DLB family which identified a locus on chromosome 2q35-q36 however, no gene was subsequently identified . This could be because the variant was not detectable with current technology or, perhaps, the linkage results were misleading.
What You Need To Know
- Lewy body dementia is a form of progressive dementia that affects a persons ability to think, reason, and process information.
- Diagnosing Lewy body dementia can be challenging an estimated 1.4 million Americans are living with the disease.
- LBD has three features that distinguish it from other forms of dementia:
- Fluctuating effects on mental functioning, particularly alertness and attention, which may resemble delirium
- Recurrent visual hallucinations
- Parkinson-like movement symptoms, such as rigidity and lack of spontaneous movement.
Lewy bodies are clumps of abnormal protein particles that, for reasons that are not fully understood, accumulate in the brain. These deposits cause a form of dementia called Lewy body dementia, or LBD which is what the late actor and comedian Robin Williams suffered from.
LBD is not the same as Parkinsons, but the two are closely related: LBD causes some or all of the motor symptoms of Parkinsons. More than 1 million people in the U.S. are affected by Lewy body dementia, according to the Lewy Body Dementia Association.
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Older Age Being Born Male And Stroke Are Known Risk Factors
Lewy body dementia is caused by protein deposits, called Lewy bodies, in parts of the brain involved in thinking, memory, and movement. The disease is characterized by a progressive decline in mental function, causing visual hallucinations and changes in alertness and attention along with Parkinson’s disease-like movement problems.
Exactly what causes Lewy bodies to accumulate is not fully understood. And until recently, the only known risk factor for developing Lewy body dementia was older age. In recent years, however, scientists have identified other factors that appear to contribute to the risk of this common and rapidly progressing form of dementia.
This article looks at nine risk factors for Lewy body dementiathe second most common cause of dementia in the United States after Alzheimer’s disease.
Genes And Late Onset Alzheimers Disease
Late onset Alzheimers disease affects people over the age of 65. It is the most common type of Alzheimers and is likely to be caused by a combination of risk factors including our age, lifetsyle and environment. Our genetics also play a part.
To date, scientists have found versions of over twenty different genes that are associated with an altered risk of developing Alzheimers disease. However, having one of these versions may only have a small effect on our total risk. There is still a lot to be understood about these genes and their role in the development of late onset Alzheimers.
The most well known gene with the largest effect on our risk is called APOE. This gene makes a protein that helps keep our brain cells healthy. There are three different versions of it APOE2, APOE3 and APOE4 and we inherit one version of the APOE gene from each parent.
People who inherit one copy of APOE4 are around three times more likely to develop Alzheimers disease. About one in fifty people inherit two copies of APOE4 one from each parent. They may be more than eight times more likely to develop Alzheimers. However, due to other contributing factors, such as age and lifestyle, people who inherit APOE4 still may never develop the disease.
More information about young onset Alzheimers disease can be found here.
Is genetic testing available for young onset Alzheimers?
You can read a personal account about deciding to be tested for a gene mutation on our blog here.
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Causes And Risk Factors
The precise cause of LBD is unknown, but scientists are learning more about its biology and genetics. For example, they know that an accumulation of Lewy bodies is associated with a loss of certain neurons in the brain that produce two important neurotransmitters, chemicals that act as messengers between brain cells. One of these messengers, acetylcholine, is important for memory and learning. The other, dopamine, plays an important role in behavior, cognition, movement, motivation, sleep, and mood.
Scientists are also learning about risk factors for LBD. Age is considered the greatest risk factor. Most people who develop the disorder are over age 50.
Other known risk factors for LBD include the following:
Diagnosis Treatment And Research
The Lewy Body Dementia Association maintains a list of its scientific and medical advisors. Many of these physicians see patients at their clinics or may make referrals to other specialists in your area. See . For general tips on finding a doctor, visit .
The Alzheimers Disease Education and Referral Center maintains a list of research centers funded by the National Institute on Aging at NIH where you may find medical specialists in Lewy body dementia: www.nia.nih.gov/alzheimers/alzheimers-disease-research-centers.
The American Academy of Neurology has a find a neurologist page on its website: .
The American Association for Geriatric Psychiatry has a physician finder on its website: .
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Is Lewy Body Dementia Hereditary
Generally, the cases of Lewy Body Dementia are not considered to be inherited. It occurs irregularly or periodically in people even if they dont have a family history. In rare cases, it has been seen that the disease can affect more than one family member. Although, this is the case when a single gene changes and follows a specific pattern of inheritance. However, in other generic cases, gene do not follow a particular pattern, and thus a multifunctional cause occurs associating with multiple genes with environmental factors and lifestyle.
When dementia is caused by SNCB or SNCA mutation it can be inherited. This means a copy of the altered gene in a single cell is enough to cause the disorder. In such cases, it has been seen that the affected person has a parent with this particular condition. People with mutation of one copy have an increased risk of developing Lewy Body Dementia.
However, scientists are making a lot of efforts in studying the exact underlying cause of inheritance.
Will I Inherit Dementia From My Parents Is It Hereditary
If youre caring for a relative living with dementia, its natural to be concerned about whether or not you or your children will develop the disease. In reality, there are actually different kinds of dementia and most of them are not hereditary.
Read on to learn about the common types of dementia, and what the chances are for people with relatives diagnosed with dementia to develop the disease.
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Requirements For Future Dlb Genetic Studies
Genetic research in DLB is only just beginning to come together, providing hope for future characterization of the genetic architecture of the disease. In order to identify additional genes implicated in DLB, it will be imperative to study more individuals with the disease. This will require collaborative approaches in order to increase cohort numbers and more studies that are focused on replicating results. As well as generating genetic data, it is important to collect detailed clinical and pathological data on patients studied.
There is a clear need for more unbiased genetic studies . The majority of genetic studies in DLB thus far have been hypothesis based, largely trying to identify candidate genes .1). Table Table11 also highlights the fact that some DLB samples have been used in multiple genetic studies, an event that should be made clear and that can severely bias results, certainly for a disease where sample collections are small.
Information About Genetic Testing
Having a test to look for a faulty gene that causes dementia is only appropriate for a very small number of people. This is because inherited dementia is rare.
If you are worried that you have a strong history family of young onset Alzheimers disease or frontotemporal dementia, you can speak to your doctor about this.
Not all gene mutations that cause dementia have been identified, meaning that some families may have many affected members, but no mutation can be found. Therefore, a negative test result cannot always rule out a genetic cause of a disease.
If a test is appropriate, your doctor should be able to refer you to a genetic counsellor or specialist. This could be a cognitive neurologist or memory clinic psychiatrist. They will discuss with you the pros and cons of taking a test and what will be involved. They will also tell you where the results will be kept, who they will be shared with, and what the next steps would be. For people found to have a genetic mutation that causes dementia, these discussions will also cover the options available if you are considering starting a family.
To find out more about genetic testing and what support is available you can visit www.raredementiasupport.org or call 020 3325 0828. Leave a message and you will be referred to the most appropriate team member.
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What Are The Benefits Of Predictive Testing
Having the test can be helpful for the following reasons:
- It can remove the anxiety of not knowing especially as the person approaches the age at which any symptoms of dementia are likely to start.
- It can give the person the option of entering into a clinical trial.
- It can help with family planning.
Genetic Study Of Lewy Body Dementia Supports Ties To Alzheimers And Parkinsons Diseases
NIH-led study locates five genes that may play a critical role in Lewy body dementia.
In a study led by National Institutes of Health researchers, scientists found that five genes may play a critical role in determining whether a person will suffer from Lewy body dementia, a devastating disorder that riddles the brain with clumps of abnormal protein deposits called Lewy bodies. Lewy bodies are also a hallmark of Parkinsons disease. The results, published in Nature Genetics, not only supported the diseases ties to Parkinsons disease but also suggested that people who have Lewy body dementia may share similar genetic profiles to those who have Alzheimers disease.
Lewy body dementia is a devastating brain disorder for which we have no effective treatments. Patients often appear to suffer the worst of both Alzheimers and Parkinsons diseases. Our results support the idea that this may be because Lewy body dementia is caused by a spectrum of problems that can be seen in both disorders, said Sonja Scholz, M.D., Ph.D., investigator at the NIHs National Institute of Neurological Disorders and Stroke and the senior author of the study. We hope that these results will act as a blueprint for understanding the disease and developing new treatments.
The study was led by Dr. Scholzs team and researchers in the lab of Bryan J. Traynor, M.D., Ph.D., senior investigator at the NIHs National Institute on Aging .
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