Alzheimer's disease is the most common cause of dementia. Its average age on onset is 75, although a small number of cases can occur as early as age 52, especially in families with an inheritance pattern. While the actually diagnosis cannot be made until after death but autopsy if desired, a clinical diagnosis is up to 90% accurate. In fact, the large majority of individuals over age 75 will have some evidence of brain deterioration from Alzheimer's disease although some will not show any impairment of MMSE testing for dementia.
Alzheimer's can also simultaneously exist with other causes of dementia, primarily vascular dementia from small strokes, hypertension, and loss of blood flow.
The diagnosis of Alzheimer's starts with a diagnosis of dementia by an MMSE or similar exam and deficits in at least two areas of cognition. If the person is experiencing a progressive deterioration of memory and cognitive functioning with no disturbance in consciousness and without other illnesses that might account for the symptoms, a diagnosis of Alzheimer's is made.
All of my Alzheimer's studies are under causes, prevention, and treatment. There are hundreds of them with lots of useful information. People can take many actions to reduce the risk of developing Alzheimer's disease. While it may be almost impossible to totally prevent the illness if you live long enough, the deterioration can certainly be delayed for years by well-researched habits of healthy living. It's probably important to start early in life, but it's never too late.
Over 80% of Elderly Over 80 Showed Evidence of Alzheimer's Damage: In a long-term follow-up of 180 elderly Catholic clergy, at the time of death, 37 had mild cognitive impairment, 83 had dementia, and 60 had no cognitive difficulties. Of the 37 with mild cognitive impairment, 23 showed brain pathology consistent with probable or definite Alzheimer's disease, and 12 had areas of dead brain tissue due to loss of blood supply. Of the 60 without cognitive impairment, 28 showed evidence of probable or definite Alzheimer's disease. One third of the group, whose average was more than 80 years, did not experience cognitive decline over several years of follow-up, despite having a significant amount of Alzheimer's disease damage. David A. Bennett, Rush Alzheimer's Disease Center, Chicago. Reuters Health NY 3/8/05.
Brain Atrophy Normal After 30, Accelerates with Alzheimer's: MRIs from 370 adults (age 18 to 97), including 98 with very mild to mild dementia of the Alzheimer type, revealed a strong linear, moderate quadratic pattern of decline beginning in early adulthood, with later onset of white matter than grey matter loss. Whole-brain volume differences were detected by age 30. The cross-sectional atrophy overlapped with the rates measured longitudinally in older, nondemented individuals (mean decline of -0.45% per year). In those individuals with very mild AD, atrophy rate more than doubled (-0.98% per year). Normative estimates of cross-sectional and longitudinal brain volume decline in aging and AD. Fotenos AF, Snyder AZ, et al. Washington University, St. Louis, MO 63108. Neurology. 2005 Mar 22;64(6):1032-9.
Most Mild Alzheimer's Patients Showed Safety Deficits on Task-Switching Driving Test: In a study of 33 mild Alzheimer patients (average MMSE 26.1 (3.0)) and 167 controls, the patients did just as well on a straight driving test, but when asked to identify roadsigns and restaurants on a one mile commercial stretch, they identified one third fewer landmarks and committed three times as many at-fault safety errors, such as failing to notice a large speed limit sign, suggesting difficulty in task switching between driving and observing (p<0.0001). Some Alzheimer patients (24%) performed well, so assessing fitness to drive should include controlled cognitive challenges while driving. Driver landmark and traffic sign identification in early Alzheimer’s disease.
Thomas E. Radecki, M.D., J.D.