What is Alzheimer’s Disease?

Alz you need to knowAlzheimer’s disease is the most common form of dementia. Dementia is an age-associated loss of cognitive function that results from physical changes in the brain, typically caused by a loss of brain tissue (degeneration). Alzheimer’s disease is named after a German physician (Alois Alzheimer) who had a patient in her 50s that developed dementia. Because she was so young, Alzheimer stained her brain with silver chemistry (borrowed from the photographic industry) and revealed two abnormal structures. One was an aggregation of degenerating tissues outside of neurons he called senile plaques. The other was twisted filaments inside neurons that he called neurofibrillary tangles.

For many years the only way to determine if a person’s dementia was caused by Alzheimer’s disease was to perform an autopsy and find senile plaques and neurofibrillary tangles in the brain. Over the last three decades we have learned that plaques are largely aggregates of a small protein called amyloid. The tangles are composed largely of aggregates of a protein called tau. In general, the plaques build up over a 20 year period before symptoms appear. Tau aggregates appear about five years before symptoms appear. Today, we have tools that permit us to detect the build-up of amyloid and tau before autopsy, permitting a definitive diagnosis of Alzheimer’s disease, as opposed to other causes of cognitive decline with age (some of which are reversible). These tools include PET scans which measure the chemistry of the brain, examination of spinal fluid, and most recently use of blood tests. Thus far these methods are not reimbursed by Medicare or insurance companies and their use remains limited, but this may change.

More information about Alzheimer’s disease and related dementias can be found on the National Institute on Aging website.

West Michigan Resources for Alzheimer’s and Dementia

Alzheimer's Alliance