Lewy body dementia is a form of dementia that may account for as many as 20% of all dementia cases. Lewy bodies are tiny spherical deposits of a protein called alpha-synuclein that are found in the brains of patients with this disorder. The presence of Lewy bodies throughout the brain disrupts the brain's normal functioning. Lewy body dementia is now believed to be the second most common specific cause of dementia after Alzheimer's disease.
There is considerable overlap between Lewy body dementia and Alzheimer's and Parkinson's disease. In Lewy body dementia, patients experience a loss of dopamine-producing nerve cells similar to that seen in Parkinson's disease. They also lose acetylcholine-producing nerve cells, similar to what occurs in Alzheimer's disease.
Patients with Lewy body dementia often experience cognitive problems associated with Alzheimer's disease, such as memory loss, spatial impairment and language difficulties. They may also develop parkinsonian symptoms, such as muscle rigidity, a blank facial expression, soft voice, tremor, poor balance and gait disturbances. Some patients initially diagnosed with Parkinson's disease later go on to develop a dementia that closely resembles Lewy body dementia.
Certain symptoms of Lewy body dementia help distinguish it however. For example, early in the illness Lewy body dementia patients often experience detailed and extremely vivid hallucinations, unlike people with Alzheimer's disease. People with Lewy body dementia also tend to show marked fluctuations in their cognitive functioning, often several times a day. In addition, they tend to fall asleep easily during the day and have restless, disturbed sleep with behavioral acting out.
Recognition of these symptoms leads to an accurate diagnosis of Lewy body dementia. A correct diagnosis is particularly important because the medical management of patients with Lewy body dementia presents special challenges. The drugs that are normally used can aggravate other problems and cause potentially serious adverse reactions. In particular, antipsychotic drugs can provoke dangerous side effects, including a return to psychosis, and must be used cautiously, if at all. In addition, levodopa, a drug normally used to treat parkinsonian symptoms, may worsen hallucinations, so its dosage needs to be carefully adjusted in patients with Lewy body dementia.
This disease is named for Frederick Lewy, the physician who first identified them in 1912 while working in the laboratory of Dr. Alois Alzheimer.
Original article from Johns Hopkins