I am posting part of an article: “Lewy Body Dementia: Causes and Symptoms” which I found in the resources section of ‘MyParkinsonsTeam’. I learned how to ‘tell the difference between Lewy body Dementia and Parkinson’s disease dementia (PDD). I am not posting the following sections of the article: Diagnosing, symptom management (with four subtitles), and building a community.
Lewy body dementia (LBD) is an umbrella term for two related types of dementia — dementia with Lewy bodies and Parkinson’s disease dementia (PDD). Dementia is a disease that progressively impairs a person’s ability to think, reason, remember, and function. Although these two conditions have overlapping features, there are also important distinctions. Understanding LBD causes and symptoms, as well as how its two subtypes, dementia with Lewy bodies and PDD, differ from one another is critical for proper diagnoses and shortening the time to start treatment.
Read abHow to tellout the diagnosis and treatment of Lewy body dementia.
Prevalence of Lewy Body Dementia
After Alzheimer’s disease, LBDs are the second most common cause of dementia in people over 65 years old. Scientists are unsure how common these dementias are. In one review of studies on dementia with Lewy bodies, its prevalence in total cases of dementia ranged from 0.3 percent to 24.4 percent, depending on the study. This inconsistency is probably because scientists are only just beginning to understand dementia with Lewy bodies and to differentiate it from Alzheimer’s disease. Another study estimates that at least 75 percent of individuals who live with Parkinson’s disease (PD) for at least 10 years will develop dementia.
Causes of Lewy Body Dementia
LBDs are poorly understood but are thought to be characterized by the buildup of Lewy bodies in the brain. Lewy bodies are groupings or clumps of badly formed (misfolded) proteins called alpha-synuclein proteins. Healthy alpha-synuclein proteins are normally found widely throughout the brain and are thought to play many roles, including participating in plasticity. This means that they affect how brain cells communicate with one another and change in response to a person’s experience. However, when these proteins misfold and accumulate, the result is Lewy bodies, which lead to cell death in the brain.
The type of LBD a person has is determined by where in the brain the Lewy bodies first begin forming. When Lewy bodies first begin to form in the cortex, dementia with Lewy bodies is the most likely result. These initial protein deposits in the cortex lead to early cognitive changes, such as inattention. When the Lewy bodies first deposit in areas of the brain more related to motor control and movement, such as the substantia nigra, PDD is the most likely result.
But what causes these Lewy bodies to form in the first place?
Genetics or hereditary elements likely play a role. The following genes are thought to be involved in the spectrum of disorders related to PD, including dementia with Lewy bodies and PDD.
The APOE gene, which makes protein apolipoprotein E. has been associated with dementia with Lewy bodies. Specifically, dementia with Lewy bodies has been associated with the presence of the ε4 variant, as has Alzheimer’s disease. PDD is not associated with this gene variant.
These diseases have also been linked to mutations in SNCA (a gene controlling the production of alpha-synuclein) and LRRK2 (a gene that controls the production of a kinase protein). LRRK2 is a particularly interesting gene, as mutations at LRRK2 are linked to the accumulation of both alpha-synuclein and tau protein (another abnormally folded protein that builds up in Alzheimer’s disease). However, more research is needed to understand the complicated role of these genes and how they may be interacting. Alterations in these proteins can lead to devastating consequences for individuals with Parkinson’s disease.
Lewy Body Dementia Signs and Symptoms
There are many signs and symptoms of LBD. A major hallmark is cognitive impairment. It is defined in the most recent version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) as cognitive decline in one or more areas (complex attention, executive function, learning and memory, language, perceptual-motor, or social cognition). People with problems in these areas might be forgetful, have problems paying attention, have trouble with problem-solving, be unable to learn new facts or skills, have difficulty with speaking or forming sentences, or have behavioral changes. These symptoms can range from mild to major, and in order to make the diagnosis, they must significantly impair a person’s day-to-day functioning.
Cognitive impairment isn’t the only hallmark of LBD. People with dementia with Lewy bodies and PDD may present very differently because of how (and where) the Lewy bodies deposit in the brain.
Dementia with Lewy bodies is characterized by three main features, according to the DSM-5:
- Problems with cognition (including marked variations in attention and alertness)
- Visual hallucinations
- Spontaneous features of parkinsonism (motor or movement symptoms), which begin after the cognitive symptoms appear
Other features that can suggest dementia with Lewy bodies are:
- Rapid eye movement sleep behavior disorder
- Sensitivity to antipsychotic medications
PDD symptoms are similar, but the timing is different. The important difference is that in PDD, parkinsonian movement symptoms (slow movement, shuffling walk, tremors, shaking, rigid muscles, muscle cramps, balance problems) start before cognitive symptoms and dementia appear.
Hallmark symptoms of both diseases include:
- Visual hallucinations — Seeing or hearing things or people that aren’t there
- Movement disorders (parkinsonism) — Slowed movement, rigid muscles, tremor, and a shuffling walk
- Cognitive problems — Confusion, poor attention, visual-spatial problems, and memory loss
- Sleep difficulties — REM sleep behavior disorder and acting out dreams while sleeping
- Emotional problems — Depression, anxiety, and apathy
Once dementia develops in someone with Parkinson’s disease (resulting in PDD), there are no clinical or biological differences that can reliably distinguish it from dementia with Lewy bodies.
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