TABLE 8-4 - Specific Diseases Asosiated with Dementia

Disease	Description
Alzheimer's	Most common cause of dementia, accounts for greater than 50% of all cases. Risk factors are familial. Down syndrome, prior head trauma, increasing age. Clinically, it is a diagnosis of exclusion. Post-mortem pathology reveals cortical atrophy, neurofibrillary tangles, amyloid plaques, granulovacuolar degeneration, loss of basal f rain cholinergic nuclei. Course is progressive, death occurs 8-10 years after onset.
Vascular	Second most common cause of dementia. Risk factors are cardiovascular and cerebrovascular disease. Neuroimaging reveals multiple areas of neuronal damage. Neurological exam reveals focal findings. Course can be rapid onset or more slowly progressive. Deficits are not reversible, but progress can be halted with appropriate treatment of vascular disease.
HIV	Limited to those cases caused by direct action of HIV on the brain; associated illnesses, such as meningitis, lymphoma, toxoplasmosis producing dementia are categorized under dementia due to general medical conditions. Primarily affects white matter and cortex.
Head trauma	Most common among young males. Extent of dementia is determined by degree of brain damage. Deficits are stable unless there is repeated head trauma.
Parkinson's	Occurs in 20-60% of individuals with Parkinson's disease. The most likely pathological finding on autopsy is Lewy body disease. Bradyphrenia (slowed thinking) is common. Some individuals also have pathology at autopsy consistent with Alzheimer's dementia.
Huntington's	Risk factors are familial, autosomal dominant on chromosome 4. Onset commonly in mid 30s. Emotional lability is prominent. Caudate atrophy is present on autopsy.
Pick's	Onset at age 50-60. Frontal and temporal atrophy are prominent on neuroimaging. The dementia responds poorly to psychotropic medicine.
Creutzfeldt-Jakob	Ten percent of cases are familial. Onset age 40-60. Prion is thought to be agent of transmission. Clinical triad of dementia, myoclonus, and abnormal EEG. Rapidly progressive. Spongiform encephalopathy is present at autopsy.