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Diagnosis of Dementia

The role of nuclear neuroimaging in the diagnosis of dementia is undergoing rapid change, however. A recent study
reported that SPECT scanning of the brains of 49 persons with dementia (with later autopsy confirmation as gold
standard) found SPECT to have sensitivity and specificity above 85% and (in the population chosen for the study)
positive predictive value of 93% and negative predictive value of 81% for accuracy 88% PMID 16785801. This is quite
similar to the accuracy of clinical exam (mental testing) results.

Interviews with family members and/or caregivers are extremely important in the initial assessment, as the sufferer
him/herself may tend to minimize his symptomatology or may undergo evaluation at a time when his/her symptoms are
less apparent, as quotidian fluctuations ("good days and bad days") are a fairly common feature. Such
interviews also provide important information on the affected individual's functional abilities, which are a key
indicator of the significance of the symptoms and the stage of dementia.

Initial suspicion of dementia may be strengthened by performing the mini mental state examination, after excluding
clinical depression. Psychological testing generally focuses on memory, attention, abstract thinking, the ability to
name objects, visuospatial abilities, and other cognitive functions. Results of psychological tests may not readily
distinguish Alzheimer's disease from other types of dementia, but can be helpful in establishing the presence
of and severity of dementia. They can also be useful in distinguishing true dementia from temporary
(and more treatable) cognitive impairment due to depression or psychosis, which has sometimes been termed
"pseudodementia".

Epidemiology and prevention

Alzheimer's disease is the most frequent type of dementia in the elderly and affects almost half of all patients
with dementia. Correspondingly, advancing age is the primary risk factor for Alzheimer's. Among people aged 65,
2-3% show signs of the disease, while 25 - 50% of people aged 85 have symptoms of Alzheimer's and an even greater
number have some of the pathological hallmarks of the disease without the characteristic symptoms. Every five
years after the age of 65, the probability of having the disease doubles. The proportion of people with Alzheimer's
begins to decrease after age 85 because of the increased mortality due to the disease, and relatively few
people over the age of 100 have the disease.

The evidence relating certain behaviors, dietary intakes, environmental exposures, and diseases to the likelihood
of developing Alzhemier's varies in quality and its acceptance by the medical community. It is important to
understand that interventions that reduce the risk of developing disease in the first place may not alter disease
progression after symptoms become apparent. Due to their observational design, studies examining disease risk
factors are often at risk from confounding variables. Several recent large, randomized controlled trials—in
particular the Women's Health Initiative—have called into question preventive mesasures based on cross-sectional
studies. Some proposed preventive measures are even based on studies conducted solely in animals.

Risk reducers

Intellectual stimulation (e.g., playing chess or doing the crossword)
Regular physical exercise
Regular social interaction
A generally healthy diet low in saturated fat supplemented in particular with:
B vitamins
Omega-3 fatty acids, especially DHA

High doses of the antioxidant Vitamin E (in combination with vitamin C) seem to reduce Alzheimer's risk in
cross sectional studies but not in a randomized trial and so are not currently a recommended preventive measure
because of observed increases in overall mortality Cholesterol-lowering drugs (statins) reduce Alzheimer's
risk in observational studies but so far not in randomized controlled trials Hormone replacement therapy is no
longer thought to prevent dementia based on data from the Women's Health Initiative Regular use of non-steroidal
anti-inflammatory drugs like ibuprofen and aspirin reduces the chance of dementia but the risks appear to outweigh
the drugs' benefit as a method of primary prevention.