What is Dementia?
Dementia is a progressive deterioration of intellectual abilities which are significant enough to interfere with the social and occupational functioning of the individual. Dementia is NOT a normal part of aging regardless of the age of the individual.
What is Mild Cognitive Impairment
There is a condition now known as Mild Cognitive Impairment where a person has problems with memory, language, or another mental function like calculation or judgment severe enough to be noticeable to others and may show up on neuropsychological testing but not severe enough to interfere with their activities of daily life. And because their cognitive problems don't impair their daily life they don't meet criteria for dementia. However, studies have shown that these persons with Mild Cognitive Impairment have an increased risk of developing Alzheimer's disease over their life time especially in the next several years. As yet there is no treatment for this disorder except for annual neuropsychological testing. It is recommended that patients with this condition be followed annually by their doctors to enable them to determine if and when the condition may develop into an Alzheimer's dementia. Medication for Alzheimer's disease is most effective when it is given early in the disease.
It is important not to dismiss memory and behavioral changes as simply old age. A thorough evaluation is necessary to determine the extent and cause of memory problems. Alzheimer's disease is the most common form of dementia, but there are many other reasons why people can have problems with their memory. Many memory problems are treatable and a supportive and caring team of health care professionals can help virtually all patients and families.
More specifically ... What is Alzheimer's Disease?
Alzheimer's disease is a progressive, degenerative disease of the brain. It is not a normal part of the aging process or a mental illness. Alzheimer's causes abnormal proteins to accumulate in and around nerve cells throughout the brain, causing them to die. Loss of nerve cells results in memory loss, impaired thinking and behavior. The disease is progressive and will eventually affect a person's daily functioning. Eventually, an individual will require around-the-clock care and supervision, with death as the inevitable outcome.
Alzheimer's disease affects an estimated 4 million Americans. It affects one in ten persons over the age of 65 and nearly half of those over 85 have Alzheimer's disease. It can occur in people in their 30's, 40's, and 50's. The disease affects both men and women, and crosses all social, economic, and cultural boundaries. Patients with Alzheimer's disease may live up to 20 years after contracting the disease. However, in the final stages of the illness they lose all abilities to care for themselves. Although many cases of Alzheimer disease may have a hereditary component, family history is not a guarantee of developing the disease. The precise cause of this illness is unknown.
Other types of dementia:
What are Prion Diseases?
The Prion diseases are a group of brain diseases caused by an infectious protein called a prion. The most common human form of prion disease is called Creutzfeldt-Jakob Disease (CJD), named after the two physicians who, in the 1920's, first described the clinical and pathological features of the disease. It is important to understand that the information shared below (symptoms and causes) primarily pertains to the clinical picture of CJD, since it represents the majority of patients who are evaluated. Yet, there are other more rare types of prion diseases with clinical presentations that differ slightly from CJD.
What are the Symptoms?
Most patients developing CJD first show signs of disorientation, general confusion, personality changes, and often have difficulty walking as well. These symptoms are associated with a rapidly progressive dementia. Within months or even weeks, the patient may exhibit severe changes in behavior, lose the ability to recognize familiar objects or people, and have difficulty with speech and language, thus requiring complete care with all basic activities of daily living. Life expectancy is usually 6 months or less after the onset of symptoms.
What Causes Prion Disease?
Most cases of prion disease are sporadic, meaning scientists don't understand what initiates the disease process. The basic mechanism of CJD, as in any prion disease, involves a change in the 3-dimensional shape of the normal prion protein in the brain to an abnormal pathogenic shape. This pathogenic protein, also simply called a "prion", acts to convert other normal prion proteins into pathogenic prions, simply by binding to them. In the end, the accumulation of prions kills brain cells.
Some cases are iatrogenic, in which a person has been exposed to contaminated brain tissue (i.e., by injection of growth hormone, corneal transplant, or surgical instrument).
Familial CJD accounts for approximately 15% of all cases. Sometimes taking a thorough family history can help trace the familial form of the disease. Familial CJD is due to the specific mutations, or defects, in the prion protein gene. The age of onset is often younger than usual (less than 55 years) and the duration of the disease is longer than usual (between 1 and 10 years). Genetic testing can reveal the presence of familial CJD in patients with the disease.
"Prion" became a household word in the 90's with "Mad Cow Disease" (Bovine Spongiform Encephalopathy, or BSE). Infected cows with BSE were found to transmit the disease across species to humans who ingested contaminated beef, causing humans to develop "New Variant CJD". The containment of this disease remains a concern worldwide. The US is focusing on careful FDA regulation of feed and cows as isolated cases of BSE have been detected in the US and Canada.
How is Prion Disease Diagnosed?
In addition to the history and physical exam, diagnostic tests that support the clinical evaluation of prion disease include:
- EEG (the electrical activity of the brain is abnormal and shows periodic sharp wave discharges)
- MRI, especially diffusion-weighted MRI (high signal changes in deep brain structures such as basal ganglia and thalamus are seen)
- Lumbar puncture to test for the presence of the 14-3-3 protein.
Is there treatment for Prion Disease?
Unfortunately, there is no medical treatment or cure for any type of prion disease, but human clinical trials are on the horizon, and one has been started. Presently, the primary focus of treatment in prion diseases is based on comfort and symptom control. Family members are faced with tough decisions, such as whether they are able to take care of the patient at home or if he/she needs to be transferred into an extended care facility. Hospice care is often a recommended option to provide ongoing comfort care at the bedside (either at home or in a facility).
Can Autopsies be Performed on Prion Disease Patients?
As with any type of dementia, autopsy is an important consideration for patients and families. The University of Chicago Memory Center strongly encourages autopsies, which are done at the Medical Center. Once the autopsy is completed after death, the patient's family can be absolutely sure that prion disease was the actual diagnosis. Autopsy is the only method to confirm a diagnosis with 100% accuracy. Many find that having this information and knowledge allows for peace and closure with their loss. Autopsy is also important in supporting research, which may help patients and families in the future with this most devastating disease in possible prevention and treatment measures.