The brain changes caused by Parkinson's disease begin in a region that plays a key role in movement. As Parkinson's brain changes gradually spread, they often begin to affect mental functions, including memory and the ability to pay attention, make sound judgments and plan the steps needed to complete a task.
The key brain changes linked to Parkinson's disease and Parkinson's disease dementia are abnormal microscopic deposits composed chiefly of alpha-synuclein, a protein that's found widely in the brain but whose normal function isn't yet known. The deposits are called "Lewy bodies".
Lewy bodies are also found in several other brain disorders, including dementia with Lewy bodies (DLB). Evidence suggests that dementia with Lewy bodies, Parkinson's disease and Parkinson's disease dementia may be linked to the same underlying abnormalities in brain processing of alpha-synuclein.
Another complicating factor is that many people with both dementia with Lewy bodies and Parkinson's disease dementia also have plaques and tangles — hallmark brain changes linked to Alzheimer's disease.
Parkinson's disease is a fairly common neurological disorder in older adults, estimated to affect nearly 2 percent of those older than age 65. The National Parkinson Foundation estimates that 1 million Americans have Parkinson's disease. It is estimated that 50 to 80 percent of those with Parkinson's disease eventually experience Parkinson's disease dementia. Sign up for our enews to receive updates about Alzheimer’s and dementia care and research.
Parkinson's disease dementia is a decline in thinking and reasoning that develops in someone diagnosed with Parkinson's disease at least a year earlier. Common symptoms include:
As with other types of dementia there is no single test — or any combination of tests — that conclusively determines that a person has Parkinson's disease dementia.
Many experts now believe that Parkinson's disease dementia and dementia with Lewy bodies are two different expressions of the same underlying problems with brain processing of the protein alpha-synuclein. But most experts recommend continuing to diagnose dementia with Lewy bodies and Parkinson's dementia as separate disorders.
Guidelines for diagnosing Parkinson's disease dementia and dementia with Lewy bodies are:
The diagnosis is Parkinson's disease dementia when a person is originally diagnosed with Parkinson's based on movement symptoms and dementia symptoms don't appear until a year or more later
The diagnosis is dementia with Lewy bodies when:
When dementia symptoms appear within one year after movement symptoms
When both dementia symptoms and movement symptoms are present at the time of diagnosis
When movement symptoms develop within a year of a dementia with Lewy bodies diagnosisSchedule An Appointment
Dementia is not a specific disease. It's an overall term that describes a wide range of symptoms associated with a decline in memory or other thinking skills severe enough to reduce a person's ability to perform everyday activities. Alzheimer's disease accounts for 60 to 80 percent of cases. Vascular dementia, which occurs after a stroke, is the second most common dementia type. But there are many other conditions that can cause symptoms of dementia, including some that are reversible, such as thyroid problems and vitamin deficiencies.
Dementia is often incorrectly referred to as "senility" or "senile dementia," which reflects the formerly widespread but incorrect belief that serious mental decline is a normal part of aging.
While symptoms of dementia can vary greatly, at least two of the following core mental functions must be significantly impaired to be considered dementia:
People with dementia may have problems with short-term memory, keeping track of a purse or wallet, paying bills, planning and preparing meals, remembering appointments or traveling out of the neighborhood.
Many dementias are progressive, meaning symptoms start out slowly and gradually get worse. If you or a loved one is experiencing memory difficulties or other changes in thinking skills, don't ignore them. See a doctor soon to determine the cause. Professional evaluation may detect a treatable condition. And even if symptoms suggest dementia, early diagnosis allows a person to get the maximum benefit from available treatments and provides an opportunity to volunteer for clinical trials or studies. It also provides time to plan for the future.
Dementia is caused by damage to brain cells. This damage interferes with the ability of brain cells to communicate with each other. When brain cells cannot communicate normally, thinking, behavior and feelings can be affected.
The brain has many distinct regions, each of which is responsible for different functions (for example, memory, judgment and movement). When cells in a particular region are damaged, that region cannot carry out its functions normally.
Different types of dementia are associated with particular types of brain cell damage in particular regions of the brain. For example, in Alzheimer's disease, high levels of certain proteins inside and outside brain cells make it hard for brain cells to stay healthy and to communicate with each other. The brain region called the hippocampus is the center of learning and memory in the brain, and the brain cells in this region are often the first to be damaged. That's why memory loss is often one of the earliest symptoms of Alzheimer's.
While most changes in the brain that cause dementia are permanent and worsen over time, thinking and memory problems caused by the following conditions may improve when the condition is treated or addressed:Schedule An Appointment
Autism, or autism spectrum disorder, refers to a range of conditions characterized by challenges with social skills, repetitive behaviors, speech and nonverbal communication, as well as by unique strengths and differences. We now know that there is not one autism but many types, caused by different combinations of genetic and environmental influences.
The term "spectrum" reflects the wide variation in challenges and strengths possessed by each person with autism.
Autism's most-obvious signs tend to appear between 2 and 3 years of age. In some cases, it can be diagnosed as early as 18 months. Some developmental delays associated with autism can be identified and addressed even earlier. Autism Speaks urges parents with concerns to seek evaluation without delay, as early intervention can improve outcomes.