Dementia and Huntington's disease are neurological disorders that result in a progressive loss of function. Huntington's disease, an inherited disease that begins when the patient is in her 30s and 40s, can progress into dementia. When a patient develops dementia, he has deficits in cognitive abilities, culminating in a complete loss of function. Huntington's disease is detected through genetic testing, while dementia tests include neuropsychological exams, brain scans and laboratory testing.
Genetic Testing
Testing for Huntington's disease can be done before the onset of the disorder to determine the patient's risk. Arthur Schoenstadt, M.D., author of the eMedTV article "Huntington's Disease Genetic Testing," states that a blood sample is drawn from the patient, then the blood is tested for the DNA mutation. A patient with Huntington's disease has more repeats of the DNA sequence CAG. A normal patient, for example, has 28 or fewer repetitions of CAG, while a Huntington's disease patient has 40 or more repetitions.
Neuropsychological Exam
Schoenstadt notes in the eMedTV article "Tests for Dementia" that an exam used to test for dementia is the Mini-Mental State Examination (MMSE), which tests for the cognitive skills that are affected for the disorder. These include orientation, attention and memory. The patient can be asked to name objects, write a sentence, follow instructions or copy an image. The MMSE is a comprehensive neuropsychological evaluation, as it covers more than one possible problem that can arise with dementia.
Brain Scans
The Mayo Clinic notes that when testing for dementia, the doctor may order brain scans, which can identify causes of dementia, such as a stroke. A brain scan also can detect a change in brain structure, which can occur with Alzheimer's disease, a type of dementia. Two brain scans can be used: CT and MRI. CT uses an X-ray to show the internal structures, and an MRI uses magnetic fields and radio waves to show the tissues in the brain. An electroencephalogram (EEG) also can be used to check for abnormalities in electrical activity.
Laboratory Tests
The doctor may request lab work to test for other disorders that have symptoms that resemble dementia. The Mayo Clinic lists checking thyroid hormone levels, performing a spinal tap, having a complete blood count (CBC) and testing blood glucose as possible laboratory tests for dementia. These tests can indicate if a patient has hypothyroidism, brain infection, anemia or diabetes, which would rule out dementia as the diagnosis. The doctor can also check vitamin B-12 levels; a deficit of this vitamin is a reversible cause of dementia.
