Vascular dementia is the second most common cause of dementia. It refers to problems with the circulation of blood to the brain that are usually the result of many small strokes or decreased blood flow. Dementia may occur when one of these strokes damages a strategic area of the brain responsible for a memory or emotion function.
Pick's disease is a disorder affecting the frontal and temporal lobes of the brain, causing progressive and irreversible decline much like Alzheimer's. Disturbances of personality, behavior and language may be noticed first and even be more severe than memory defects. Depending on the lobe affected, symptoms may include loss of social and sexual inhibition, impaired judgment, hoarding items, roaming, difficulties with attention and motivation, aphasia, repetitive speech patterns or the tendency to repeat anything heard. Named for Dr. Arnold Pick who reported the first case in 1892, the onset of the disease is typically in the mid-to-late 50's, and the disease averages about 10 years from onset to death. The cause remains unknown, and until PET the only way to diagnose Pick's disease was after autopsy.
Huntington's disease (HD) is an inherited, degenerative brain disease that affects the mind and body. It slowly diminishes the affected individual's ability to walk, think, talk and reason. Named for Dr. George Huntington who first described this hereditary disorder in 1872, HD is now recognized as one of the more common genetic disorders. More than a quarter of a million Americans have HD or are at risk of inheriting the disease from an affected parent. Early symptoms may include depression, mood swings, forgetfulness, clumsiness, involuntary twitching and lack of coordination. As the disease progresses, concentration and short-term memory diminish and involuntary movements of the head, trunk and limbs increase. Walking, speaking and swallowing abilities deteriorate. HD typically begins in mid-life, between the ages of 30 and 45. In 1993, the HD gene was isolated, and a direct genetic test was developed which can accurately determine whether a person carries the HD gene. The test cannot predict when symptoms will begin. Since the discovery of the gene, HD research has accelerated and much has been added to our understanding of the disease. PET has been instrumental in this breakthrough HD research.
Brain Tumor
Brain cancer is initially suspected because of the symptoms it causes. Symptoms usually occur gradually, becoming worse over time. They can also happen suddenly like a stroke. Once tumor patient was diagnosed after he had a sudden seizure and then seemed to lose his short-term memory. No screening test is currently available to detect brain cancer. Survival is determined by the type of tumor and its location, not by how early it's detected.
Brain tumors often interfere with the specific functions of the region in which they develop. According to the American Cancer Society, headache is a common symptom of brain tumor, occurring in about 50% of patients. This is due to rising pressure within the skull, which can also cause nausea, vomiting or blurred vision. If symptoms suggest a tumor, a neurological examination will be administered to the patient and imaging studies will be ordered.
- PET is the only imaging technique that can differentiate
between the dementias, ruling out Alzheimer's for example, and positively
diagnosing a metabolic pattern for Pick's and Huntington's disease.
This is extremely important for directing patient treatment programs,
since most dementias are not yet curable. PET is also being used by
scientists searching for answers to these diseases. Hopefully, there
will be a cure soon.
- Brain tumor evaluation was the first demonstrated
clinical application of PET and is now used to grade the degree of malignancy,
check for recurrence--especially differentiating surgical changes like
scar tissue fromm recurrent tumor, provide physicians with prognostic
information, and pinpoint the most active tissue for biopsy.