brain, spinal cord, and nerve disorders
Dementia With Lewy Bodies and Parkinson Disease Dementia
Changes in the brain
In dementia with Lewy bodies and Parkinson disease dementia, abnormal round deposits of a protein (called Lewy bodies) form in nerve cells. Lewy bodies result in the death of nerve cells. In dementia with Lewy bodies, the Lewy bodies form throughout the outer layer of the brain (gray matter, or cerebral cortex). The cerebral cortex, which is the largest part of the brain, is responsible for thinking, perceiving, and using and understanding language. In Parkinson disease dementia, the Lewy bodies tend to form in part of the brain called the substantia nigra, the part that is affected in Parkinson disease. The substantia nigra is located deep within the brain stem and helps make movements smooth. The brain stem connects the brain with the spinal cord. Dementia with Lewy bodies and Parkinson disease dementia may be variations of one disorder. In this disorder, synuclein (a protein in the brain that helps nerve cells communicate) changes shape (misfolds) and slowly accumulates mostly in the brain but also in the digestive tract and heart. These abnormal deposits of synuclein are called Lewy bodies. The misfolded synuclein in Lewy bodies triggers more synuclein to misfold, resulting in the formation of more Lewy bodies. Brain damage results from the accumulation of Lewy bodies. Misfolded proteins that cause brain damage in this way are called Overview of Prion Diseases . Prions cause other brain disorders such as Lewy bodies also develop in some people with Alzheimer disease, although neurofibrillary tangles and neuritic (senile) plaques seem to be the main source of damage. Neurofibrillary tangles and neuritic plaques, typical in Alzheimer Disease , sometimes develop in people who have dementia with Lewy bodies. Dementia with Lewy bodies, Parkinson disease dementia, and Alzheimer disease overlap considerably, and more research is needed to clarify their relationships. 