Dementia can only be definitively diagnosed post-mortem. Even so, diagnoses of probable dementia can be fairly accurate. The most well-known form of dementia is Alzheimer's disease, but dementia can result from many different etiologies, including vascular, demyelinating, inflammatory, neoplastic, infections, and inflammatory.
The prevalence of dementia at age 60 is 1% and the prevalence doubles every five years thereafter to age 85, when the prevalence is 30-50%.
Alzheimer's is the most common cause of dementia and accounts for over half of the patients who present with cognitive changes. Vascular dementia is probably the second most common form of dementia, though Lewy Body dementia is not far behind.
Differentiating dementias
One popular way of differentiating dementias is to classify them as cortical or subcortical. ★Cortical dementias, such as Alzheimer's disease, often have deficits starting with A's:
Subcortical dementias involve deeper structures, and are manifest as Parkinson's and Huntington's disease. There are several characteristics that differentiate cortical and subcortical dementias.
Alzheimer's disease is gradual and progressive. Memory impairment is often one of the first symptoms, which progresses to aphasia, apraxia, and anomia. Lewy body dementia can be challenging to differentiate from Alzheimer's disease, but can be diagnosed post mortem.
Vascular dementia is classically characterized by a stepwise progression of symptoms in contrast to the gradual ones of Alzheimer's disease. After progressive infarcts, vascular dementias are often called multi-infarct dementia. Patients with vascular dementias often have a history of hypertension, stroke, and depression.
Alcoholism is also associated with dementia. ★There is an inverted U relation between alcohol consumption and dementia. 13 drinks are less per week are associated with a decreased risk of dementia, but over 13 drinks per week is associated with a risk for dementia.
★Pseudodementia refers the likelihood of diagnosing an older depressed patient because the symptoms of depression can imitate those of dementia. One can differentiate between the two.