The Dementias

 

dementia: condition of gradual, insidious, and relentless loss of cognition, as well as deterioration of social capabilities.

 

Dementia of the Alzheimer's Type:(DAT) marked by significant memory impairments. Gradual onset and continuous cognitive decline.

 

Vascular Dementia:(multi-infarct dementia) arises from many small cortical and subcortical infarcts. Abrupt onset.

 

Pick's Disease: personality and social behavior alterations are seen first, then cognitive impairments.

 

Lewy Body Dementia: senile plaques, neurofibrillary tangles, and presence of LEWY BODIES. Exhibit cognitive deterioration and body rigidity.

 

 

 

 

Dementia of the Alzheimer's Type (DAT)

 

-shrinkage of frontal and temporal gyri and ventricle enlargement.

-classic pathological symptoms:

    1. neurofibrillary tangles: strands of axonal material that displace normal neurons.
    2. senile plaques: spherical structures made up of glia and abnormal nerve processes.
    3. granulovascular degeneration: results in neuronal tissue becoming full of holes.
    4. amyloid protein deposits: degenerated nerve cell material with an amyloid-filled core.

-affects cholinergic pathways.

-Etiology: not known, but a few causes have been suggested:

    1. environmental agents: environmental toxins, aluminum (has been found in tangles and plaques).
    2. transmissible agents: disease transmission. Example: a virus, such as Creuzfeldt-Jakob disease.
    3. disturbed metabolism: PET studies have shown a reduction in glucose metabolism in frontal, parietal, and temporal regions in DAT.
    4. immunological abnormalities: antibodies against brain tissue are present in DAT patients.
    5. genetic predisposition: Individuals with two genes for APO-E4 are eight times more likely to inherit DAT than people who inherit other more common gene variants for the APO-E protein. Thus, APO-E4 is a risk factor in developing DAT.