Dementia with Lewy bodies, also known as Lewy body dementia or diffuse Lewy body disease, is a type of dementia that usually accompanies Parkinson's disease. Anatomically, it is characterized by the presence of Lewy bodies and alpha-synuclein and ubiquitin protein deposits in the nerves. These substances can be detected during a postmortem brain autopsy. Lewy body dementia is a progressive memory loss that primarily affects older adults. The characteristic feature of this disease is a gradual decline in cognitive ability, which leads to hallucinations and poor comprehension and attention to what is in the patient's surrounding environment compared to a healthy person. People with Lewy body disease show an inability to plan and think and varying changes in perception. The alertness of these patients varies from day to day, and their attention and short-term memory vary. Persistent or intermittent visual hallucinations accompanied by clear images and visions are early signs of this disease. The patient's sleep pattern can be disturbed, accompanied by vivid visions, recurring dreams, violent deliberate movements, and then falling out of bed. Lewy body disease overlaps medically with Alzheimer's and Parkinson's diseases, but it accompanies Parkinson's disease more. For this reason, when this disease was discovered in its early years, it was not diagnosed correctly. In Lewy disease, it was believed that the loss of acetylcholine-producing neurons was the cause of the decline in cognitive function - which is somewhat similar to Alzheimer's - while the loss of dopamine-producing neurons was responsible for the gradual loss of control over voluntary functions - which is similar to Parkinson's disease - so this disease resembles both of the previous diseases. Therefore, the overlap between these three diseases makes the diagnosis of Lewy body disease more difficult, so that it can sometimes be confused with the early symptoms of Alzheimer's disease and vascular dementia. However, it is possible to distinguish between Alzheimer's, which develops slowly, and Lewy body disease, which develops and begins suddenly and rapidly, especially in the first months of the disease. Although it is difficult to identify and identify this disease, an accurate diagnosis is necessary to avoid the greatest number of side effects of antipsychotic drugs and thus provide treatment that can improve the life of the person with Lewy body disease and the people around him. The use of medications containing benzodiazepines, antidepressants, anticholinergics, and over-the-counter cold medications may lead to psychosis and hallucinations for a short period. The known dementia associated with Parkinson's disease and that associated with Lewy bodies can be distinguished by the time they appear with Parkinson's disease. In the first, dementia associated with Parkinson's disease is diagnosed when the dementia appears more than a year after Parkinson's disease has started. While dementia associated with Lewy bodies is diagnosed when the time of the patient's mental decline is known at the same time as the onset of Parkinson's disease symptoms or during the first year of its onset. Symptoms vary from person to person, but the core symptoms of the disease include changes in the level of cognition with large differences in the level of attention and comprehension from day to day and from hour to hour, varying episodes of hallucinations, and motor symptoms associated with Parkinson's disease. Other symptoms such as sleep disturbances and other signs can be detected by CT scan. Parkinson's disease symptoms associated with Lewy body dementia include a shuffling gait, decreased ability to control facial muscles, stiffness or rigidity when moving, a low voice level when speaking, thick saliva and difficulty swallowing. Involuntary body tremors in people with Lewy body disease are less common than in Parkinson's disease. People with this disease also have problems with postural hypotension, falls and frequent loss of consciousness. Sleep-disordered breathing can be a symptom of multiple system atrophy. A well-known and important medical sign of this disease is severe sensitivity to antipsychotic and antiemetic drugs that affect the nerves that produce acetylcholine and dopamine. This sensitivity can lead to complete paralysis, complete loss of consciousness or can expose him to a dangerous state of muscle rigidity. Therefore, these drugs should not be used or used with caution. Hallucinations that people with Lewy body disease often see people or animals that are not there, which may indicate the presence of Lewy bodies in the temporal lobe. Symptoms of psychosis include the feeling of being in two or more different places at once, etc. Hallucinations and psychoses can be disturbing, but not all of them are experienced as being pleasant or knowing that they are not real. Patients also suffer from visual disturbances, including double vision and misinterpreting what they are looking at, such as thinking that what they are looking at is a group of snakes when it is actually a pile of socks. The exact cause of Lewy body disease is not yet understood, but a link has been described to the gene PARK11. Like Alzheimer's and Parkinson's, Lewy body disease tends to run in generations, so its genetic link is not strong. However, like Alzheimer's, the risk of developing the disease increases when a person inherits the ε4 allele of apolipoprotein E. Pathophysiologically, Lewy body disease is characterized by deposits of Lewy body proteins in various parts of the brain. These deposits are known as Lewy bodies. These bodies are somewhat similar to the protein deposits under the cerebral cortex in Parkinson's disease. In addition, the neurons that produce both dopamine and acetylcholine are lost or destroyed, just as occurs in Parkinson's and Alzheimer's diseases, respectively. Also, the brain shrinks or shrinks in size as the cerebral cortex deteriorates. Postmortem examination of the brain showed epidemiological signs similar to Alzheimer's disease. The deposits of Lewy bodies that appeared in the cortex also appeared in Alzheimer's disease, but they were found deposited in the hippocampus, in addition to granular deposits in the space around the hippocampus. It is not yet known whether Lewy body disease is a type of Alzheimer's disease or a separate disease. Unlike Alzheimer's, Lewy body disease does not show any visible atrophy when the brain is examined. There is no cure for Lewy body disease. However, there is a medication that works to relieve the symptoms of this disease but does not help in its disappearance and is used as a pain reliever. We can divide the current treatment methods into drug therapy and care. Drug therapy is treated by balancing the treatment of the motor, emotional, and cognitive symptoms of this disease. Motor symptoms respond to the drug used to treat Parkinson's disease, and cognitive problems may improve with Alzheimer's medication. An estimated 60 to 75% of people diagnosed with dementia have either Alzheimer's disease or a combination of the two. 10 to 15% of dementia cases are due to Lewy body disease, with other types of dementia accounting for the last 15-20%, such as frontotemporal lobe atrophy known as Pick's disease, alcoholic dementia, and others. Lewy body disease affects men more than women. This disease affects about one million people in the United States alone. The protein deposits that cause this disease were first discovered by the scientist (Frederick Lewy) in the early eighteenth century. But the first person to describe the disease was the Japanese neuropsychologist in 1976. The diagnosis of Lewy body disease began in the mid-nineties after the discovery of the alpha-synuclein stain, which revealed Lewy bodies in the cerebral cortex during autopsies of patients who had dementia. The disease was not included in the Diagnostic and Statistical Manual of Mental Disorders, which was published in 1994, but it was briefly described in the 2000 edition of the manual under the name . In 1996, some scientists called for an amendment and then a revision of the diagnostic guidelines for this disease.