"This web page was produced as an assignment for Genetics 564, an undergraduate capstone course at UW-Madison."
What Is Lewy Body Dementia?
Lewy body dementia (LBD) is a neurodegenerative disease often characterized by loss of memory, confusion, hallucinations and impaired thinking and attention (1). Lewy body dementia may also affect motor skills and coordination, leading to tremors and loss of balance.
LBD is caused by abnormal alpha-synuclein protein deposits in the brain (1). These proteins accumulate, causing damage, killing cells and interrupting normal brain function. LBD is closely related to Parkinson's Disease (PD); however, the location of the alpha synuclein-protein aggregates distinguishes the two diseases. In PD, the proteins aggregate in the substantia nigra, an area located in the midbrain that is responsible for movement (2). However, the alpha-synuclein proteins associated with LBD are distributed throughout the cerebral cortex, affecting different aspects of memory and motor control (2). |
Is it Lewy Body Dementia or Something Else?
Parkinson's Disease (PD), Parkinson's Disease dementia (PDD), and Lewy body dementia (LBD) often share many similar symptoms, making diagnosis difficult. However, there are key differences in symptom onset and timing for each disease. Parkinson's disease often causes progressive motor impairment, and does not share many of the cognitive symptoms that are characteristic of PDD and LBD. Parkinson's disease dementia and Lewy body dementia share many of the motor and cognitive symptoms, but if dementia symptoms onset after motor impairment, this is diagnosed as Parkinson's disease dementia (3). However, if cognitive impairment precedes motor, this is Lewy body dementia (3).
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The SNCA Gene
The SNCA gene encodes the alpha-synuclein protein, commonly found in the brain and throughout the body. Alpha-synuclein is often located in the presynaptic nerve terminals of neurons (4). Little is known about the normal function of this protein, but studies have found that this protein likely helps maintain synaptic vesicles in the presynaptic terminals (4). It may also help control dopamine release (4). SNCA is located on chromosome 4 at the location q21.3-q22.1 (5).
What Causes Lewy Body Dementia?
The exact cause of Lewy body dementia remains largely unidentified. However, scientists know that accumulation of Lewy body proteins in the brain can cause the loss of two important neurons (6). These neurons are responsible for producing acetylcholine and dopamine, two neurotransmitters that are important for memory, cognition and movement (6). Some individuals may have an inherited form of LBD, but most often the cause of the disease is unknown. The familial form of LBD caused by SNCA or SNCB mutations is autosomal dominant, meaning it requires only one copy of the mutated gene to exhibit a phenotype (7). These inherited forms are thought to comprise only about 10% of LBD cases (3).
Prevention and Treatment
There is currently no cure for Lewy body dementia, but the burden of some symptoms may be delayed or reduced with medication and life style changes. Routines such as a healthy diet, adequate exercise, and mental exercises may help delay the onset of symptoms (6). Medications to manage hallucinations and tremors may also be effective.
Resources and Foundations
references
1. What is LBD?-Lewy Body Dementia Association. (2016). Retrieved from https://www.lbda.org/category/3437/what-is-lbd.htm
2. Science-The Lewy Body Society. (2016). Retrieved from https://www.lewybody.org/about-dlb/science/
3 Lewy Body Denentias-UCSF Memory and Aging Center. (2018). Retrieved from https://memory.ucsf.edu/lewy-body-dementias
4. SNCA Gene-Genetics Home Reference. (February, 2018). Retrieved from https://ghr.nlm.nih.gov/gene/SNCA
5. Siddiqui, I. J., Pervaiz, N., & Abbasi, A. A. (2016). The Parkinson's Disease Gene SNCA: Evolutionary and structural insights with pathological implication. Scientific Reports, 6, 1-11. DOI: 10.1038/srep24475
6. What Causes Lewy Body Dementia?-NIH National Institute on Aging. (May, 2017). Retrieved from https://www.nia.nih.gov/health/what-causes-lewy-body-dementia
7. Dementia With Lewy Bodies-Genetics Home Reference. (October, 2017). Retrieved from https://ghr.nlm.nih.gov/condition/dementia-with-lewy-bodies#inheritance
Cover photo reference:
http://pixshark.com/lewy-bodies-vs-pick-bodies.htm
2. Science-The Lewy Body Society. (2016). Retrieved from https://www.lewybody.org/about-dlb/science/
3 Lewy Body Denentias-UCSF Memory and Aging Center. (2018). Retrieved from https://memory.ucsf.edu/lewy-body-dementias
4. SNCA Gene-Genetics Home Reference. (February, 2018). Retrieved from https://ghr.nlm.nih.gov/gene/SNCA
5. Siddiqui, I. J., Pervaiz, N., & Abbasi, A. A. (2016). The Parkinson's Disease Gene SNCA: Evolutionary and structural insights with pathological implication. Scientific Reports, 6, 1-11. DOI: 10.1038/srep24475
6. What Causes Lewy Body Dementia?-NIH National Institute on Aging. (May, 2017). Retrieved from https://www.nia.nih.gov/health/what-causes-lewy-body-dementia
7. Dementia With Lewy Bodies-Genetics Home Reference. (October, 2017). Retrieved from https://ghr.nlm.nih.gov/condition/dementia-with-lewy-bodies#inheritance
Cover photo reference:
http://pixshark.com/lewy-bodies-vs-pick-bodies.htm