There are many cognitave disorders. Dementia is a very common disease found in the elderly The World Health Organization defines dementia "as a disease of the brain, usually of a chronic or progressive nature, in which there is disturbance of multiple cortical functions, calculation, learining capacity, language and judgment. Consciousness is not clouded. Impairments of cognitive function are common and occasionally preceded by deterioration in emotional control, social behavior, and motivation."(McCance and Heuther pg 552)

There are several factors contributing to the dementing process. They are as follows. 1. degeneration which can be caused by genetics, inflammation, or biochemical alterations. (McCance and Heuther pg 553) 2. atherosclerosis, and infacrction throughout the thalami, basal ganglia, cerebral projection pathways, and other areas. 3. trauma or leasion in the cerebral convolutions usually in the frontal or temporal regions. 4. increased inctercranial pressure and hydrocephalus. The environement may also play a role in the dementing process however there has been no definative answer as to what environemtnal factors that may increase a patients risk for developing dementia. Exposure to aluminum has been thought to cause dementia however it is not clearly understood at this time.

Causes of dementia vary. There are eight typically categories of underlying causes of dementia. They are as follows. 1.degenerative disease of the central nervous system (senile dementia, Alzheimer's disease, Lewy body disease, and multiple sclerosis), 2. Intracranial causes(tumors, chronic subdural hematoma's, and aneurysm), 3. Vascular causes (occlusion of the coronar artery, strokes, and hypertension), 4. Metabolic and endocrine abnormalities ( renal failure, hypoxia, and hypercalcemia), 5. Nutrition deficiencies (lacking vitamin b12 intake, decreased thiamine) 6. trauma (severe head injury, and repeated head injury), 7. Infections (encephalitis, chronic meningitis, and AIDS), 8. toxic causes (alcholol, drugs, and poisoning). (Current Nursing 2011)

There are several different types of dementia including: Alzheimer disease, Creutzfeldt-Jakob disease, Dementia with Lewy body, frontotemporal dementia, and vascular dementia. Each type of dementia presents with different clinical manifestations.

Alzheimer's disease is the leading type of dementia found in the elderly however it can be found in younger patients as well. Alzheimers occurs when neruons are lost in the parts of the brain dealing with memory and cognition. There is also a build up of proteins on the brain cells. The symptoms of alzeimers disease are memory loss, impaired learning ability,and normal progressive cognative impairment The cause of Alzheimer's disease is unknown however some physicians believe that there may be a genetic factor.

Vascular dementia is a dementia caused by decreased blood flow to the brain