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.

 DAT Continued...

-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.