Life expectancy has nearly doubled since the beginning of the 20th century In America, the average life expectancy is now about 78 years. (1) Demographers predict that most babies born after 2000 in relatively wealthy countries like the U.S. will celebrate their 100th birthday in the 22nd century. (2) Although the quest to find "fountain of youth" genes has been unsuccessful, senescence has been delayed because better medical care, diet, living conditions, and education have shifted the balance between damage to and repair of the body. This is good news.
The bad news is that biomedical science has not yet found a way to repair the damage to the brain caused by various forms of dementia. This means that even though physical senescence and death occur later, the number of people diagnosed with some form of dementia is increasing as more people live longer.
Currently, the most significant risk factor for dementia is old age, and by 2030, more than 19 percent of Americans will be 65 and older. (3) Of the approximately 78 million American baby boomers (born between 1946 and 1964), about 14 million will develop Alzheimer's disease (AD) and/or some other form of dementia. (4) If they live to age 85 and older, 45 percent can expect to be living with dementia. The Alzheimer's Association estimates that about 5.4 million Americans have AD now and up to 16 million will by 2050. (5) Researchers at Duke University calculated that among Americans age 71 and older, 13.9 percent have some form of dementia, with AD accounting for the majority of these cases. (6) In addition to persons with diagnosable dementia, about 22 percent of those age 71 and older have mild cognitive impairment that is noticeable to themselves or to others but does not interfere with their daily activities. (7)
Current annual costs of direct care for those with AD or other dementia total about $200 billion in the U.S. Family members and friends also provide unpaid care valued at $210.5 billion each year. (8) The rising number of persons living with dementia extends beyond America and has become such a global phenomenon that last year, the World Health Organization named it as a social and public health priority. (9)
Aspects of dementia
Dementia generally means progressive loss of cognitive functions that diminish memory, language, decision-making, abstract thought, and performance of familiar tasks. Dementia can also alter personality and produce disorientation about time and place. AD is the most common form of dementia. People with AD struggle to recall recent events; one way of describing this is to say their memory loses its "stickiness." Often, this problem leads them to ask the same questions repeatedly. (10) Over time, the pathological changes in the brain that trigger these cognitive problems accumulate, become more severe, and ultimately lead to death.
Some of the many different types of dementia result from reversible conditions like depression, hormonal problems, medications, nutritional deficiencies, tumors, infections, and alcohol and drug abuse. (11) Medical intervention can sometimes reverse the course of cognitive decline for these conditions. The most common irreversible dementias are AD, vascular brain injury usually caused by cerebral microinfarcts "mini-strokes", and Lewy body dementia, which produces visual hallucinations, deficits in attention and concentration, and Parkinsonian symptoms. (12-13) Although most people receive one dementia diagnosis, research increasingly shows that individuals may have more than one type, especially as they gel older. (14)
The German psychiatrist and neuropathologist Alois Alzheimer identified AD in 1906. His autopsy studies revealed plaques between the nerve cells of the brains of afflicted persons and tangled material inside the nerve cells. Scientists later discovered that the plaques are made up of the protein amyloid beta (AB) and the tangles result from changes in the tau protein that produce a breakdown of the microtubules that provide structure to nerve cells and transport proteins and other substances. …