What is mild cognitive impairment?
Mild cognitive impairment (MCI) is a condition in which people have more memory or other thinking problems than normal for their age, but their symptoms do not cause disability. Older people with MCI are at greater risk for developing dementia caused by Alzheimer’s, but not all of them do. Some may even go back to normal cognition. Studies are underway to learn why some people with MCI progress to Alzheimer’s dementia and others do not.
The problems associated with MCI may also be caused by certain medications, cerebrovascular disease (which affects blood vessels that supply the brain), and other factors, including depression or anxiety. Some of the problems brought on by these conditions can be managed or reversed through treatment at places like the Penn Memory Center.
The type of MCI with memory loss as the main symptom is called amnestic MCI. In another type, non-amnestic MCI, the main symptom is an impaired thinking skill other than memory loss, such as trouble planning and organizing or poor judgment.
What is dementia?
Dementia is the loss of cognitive functioning—thinking, remembering, and reasoning—and behavioral abilities to such an extent that it causes disability, meaning, it interferes with a person’s daily life and activities. Dementia ranges in severity from the mildest stage, when it is just beginning to affect a person’s functioning, to the most severe stage, when the person must depend completely on others for basic activities of daily living.
Many conditions and diseases cause dementia. The most common cause of dementia in older people is Alzheimer’s disease. Other causes include different kinds of brain changes that lead to vascular dementia, Lewy body dementia, and frontotemporal disorders.
In addition, some people have mixed dementia—a combination of two or more disorders, at least one of which is dementia. A number of combinations are possible. For example, some people have Alzheimer’s disease and vascular dementia at the same time.
What is Alzheimer’s disease?
Alzheimer’s disease is an irreversible, progressive brain disorder that slowly destroys memory and thinking skills and, eventually, the ability to carry out the simplest tasks. In most people with Alzheimer’s, symptoms first appear in their mid-60s. Alzheimer’s disease is the most common cause of dementia and MCI among older adults.
The disease is named after Dr. Alois Alzheimer. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. Her symptoms included memory loss, language problems, and unpredictable behavior. After she died, he examined her brain and found many abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary, or tau, tangles).
These plaques and tangles in the brain are still considered some of the main features of Alzheimer’s disease. Another feature is the loss of connections between nerve cells (neurons) in the brain. Neurons transmit messages between different parts of the brain, and from the brain to muscles and organs in the body.
Although treatment can help manage symptoms in some people, currently there is no cure for this devastating disease.
What is vascular dementia?
Vascular dementia, considered the second most common form of dementia after Alzheimer’s disease, results from injuries to the vessels supplying blood to the brain, often after a stroke or series of strokes. Vascular dementia and vascular cognitive impairment arise as a result of risk factors that similarly increase the risk for cerebrovascular disease (stroke), including atrial fibrillation, hypertension, diabetes, and high cholesterol. The symptoms of vascular dementia can be similar to those of Alzheimer’s, and both conditions can occur at the same time. Symptoms of vascular dementia can begin suddenly and worsen or improve during one’s lifetime.
Research has shown that Alzheimer’s and vascular disease-associated cognitive impairment are closely intertwined. For example, a large proportion of people diagnosed with Alzheimer’s also have brain damage caused by vascular disease. In addition, several studies have found that many of the major risk factors for vascular disease may also be risk factors for Alzheimer’s.
The overlap between these two types of dementia may be important because medications and lifestyle changes known to help prevent vascular disease, such as controlling high blood pressure, lowering cholesterol, and engaging in physical activity, may also help prevent Alzheimer’s disease.
What is Lewy body dementia?
Lewy body dementia (LBD) is another common brain disorder in older people. LBD is caused by abnormal deposits of a protein called alpha-synuclein in the brain. These deposits, called Lewy bodies, can lead to problems with thinking, movement, behavior, and mood. For example, symptoms may include changes in alertness and attention, hallucinations, tremor, muscle stiffness, sleep problems, and memory loss.
The two types of LBD are:
- Dementia with Lewy bodies, in which cognitive symptoms appear within a year of movement problems
- Parkinson’s disease dementia, in which cognitive problems develop more than a year after the onset of movement problems
Lewy body dementia can be hard to diagnose because Parkinson’s disease and Alzheimer’s disease cause similar symptoms. Scientists think that LBD might be related to these diseases, or that they sometimes happen together.
For Lewy body dementia research at the University of Pennsylvania, visit the Penn FTD Center.
What is frontotemporal disorders?
Frontotemporal disorders are a form of dementia caused by a family of brain diseases known as frontotemporal lobar degeneration (FTLD). These disorders are the result of damage to neurons (nerve cells) in parts of the brain called the frontal and temporal lobes. As neurons die in the frontal and temporal regions, these lobes atrophy, or shrink. Gradually, this damage causes difficulties in thinking and behaviors controlled by these parts of the brain. Many possible symptoms can result. They include strange behaviors, emotional problems, trouble communicating, or difficulty with walking and other basic movements.
Frontotemporal disorders can be grouped into three types, defined by the earliest symptoms physicians identify when they examine patients.
For FTD research at the University of Pennsylvania, visit the Penn FTD Center.
What is Parkinson’s disease?
Parkinson’s disease (PD) belongs to a group of conditions called motor system disorders, which are the result of the loss of dopamine-producing brain cells. The four primary symptoms of PD are tremor, or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking, or completing other simple tasks.
PD usually affects people over the age of 60. Early symptoms of PD are subtle and occur gradually. In some people the disease progresses more quickly than in others. As the disease progresses, the shaking, or tremor, which affects the majority of people with PD may begin to interfere with daily activities. Other symptoms may include depression and other emotional changes; difficulty in swallowing, chewing, and speaking; urinary problems or constipation; skin problems; and sleep disruptions.
There are currently no blood or laboratory tests that have been proven to help in diagnosing sporadic PD. Therefore the diagnosis is based on medical history and a neurological examination. The disease can be difficult to diagnose accurately. Doctors may sometimes request brain scans or laboratory tests in order to rule out other diseases.
For Parkinson’s disease research at the University of Pennsylvania, visit the Udall Center for Parkinson’s Research.