Alzheimer's Disease: past, current, and future treatments

December 4, 11:34 AMScience News ExaminerMeg Marquardt

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Agustine D., the first AD patient described by Alzheimer in 1906.

As we leave Alzheimer's Awareness Month, I take an in-depth look at the history and exciting future of AD treatment.

 Part I: A Historical Perspective

The history Alzheimer’s disease (AD) is a short-lived one.  It was identified by Alois Alzheimer as a unique manifestation of dementia in 1906, a time when senile dementia had been made a popular topic by the likes of Freud. But what of all the time before the 20th century?  Certainly people were suffering from AD and dementia long before the modern period.  It could be argued that there were few cases of people afflicted with diseases associated with old age simply because they are not living to an old age.  The typical onset of AD is around the age of 60, and the average worldwide lifespan did not reach 60 until recent times.  The World Health Organization estimates that the average global life expectancy was 31 years in 1900—and below 50 years in wealthy, developed countries.  So in 1906, when Alzheimer first outlined the disease, there is a chance that there had been relatively few cases that were noticed, let alone studied.  

There were other factors leading to a lack of investigation into AD, assumptions made by scientists and complacency leading the pack.  It was generally held that dementia was an inevitable and normal process of aging.  It was not a disease in the same way that polio was, did not strike indiscriminately like influenza.  It was a natural outcome of growing old and thus did not warrant a terribly large amount of study.  Indeed, the years that followed Alzheimer’s description of the illness were markedly void of any further interest in the disease.

AD shares nearly every symptom of traditional dementia: memory loss is the first sign with impairment of complex motor skills and eventually severe changes in mood following.  The two diseases also share similar brain pathology (with pathology in this case referring the physical manifestation of the causes of a disease) in the accumulation of what is known as senile plaques, a buildup of harmful protein both in and on brain matter.  Unique to AD, however, as noted by Alzheimer in his retrospectively groundbreaking study, is the additional accumulation of neurofibrillary tangles in the brain.  These tangles, also known as Tau tangles after the tau-protein they are composed of, are regarded as the more toxic aspect of AD brain pathology, even greater than the amyloid-beta (Aβ) peptides that create the plaques.  Both accumulations greatly hinder the survival rate of neurons, a process which in the end lead to the symptoms of memory loss, degradation of motor function, and the like.

Even with the identification of these unique tangles, AD and the other dementias were given very little consideration until the 1940s.  Up to that point, no clear clinical connection could be made between the severity of dementia and the plaques found in the brain, and thus their involvement with dementia remained misunderstood and poorly studied.  But after WWII, there was a sudden emergence of a need to deal with an ever-aging population.  People were living longer than ever before and that not only meant that there was a push to find a solution as to what society was to do with a large elderly population, but it also meant that there was a higher incidence of age-related diseases like AD and dementia.  And then something strange happened, an outcome that is perhaps not that surprising given the fact that this era is historically known as the Age of Anxiety.  Dementia was no longer viewed as a physical disease at all—it became solely a mental one.  Talks of plaques were discarded in favor of precarious mental states being the cause of dementia.  It was because the elderly were being forced into retirement and then into nursing homes, cut off from their families and left with nothing for which to be responsible or to work for, that caused their dementia.  As this sounded remarkably like the causes of depression, treatments with hormones and psychotherapy were offered with little-to-no-success.  But this reaction was effective in drawing attention away from the plaques, turning them into an effect rather than a cause, creating a disease which causes were a reflection of a society’s own growing distress and anxiety about the future.

It was not until the 1970s that the current era of AD understanding came into being.  The term "ageism" was coined to explain the bigotry towards the older generation, a frame of mind that held onto the assumption that degradation of physical and mental health was a natural and irreversible part of aging. This movement to treat aliments such as dementia as a disease rather than an inevitability led to new studies of the plaques and tangles found in the brain, these considerably more robust and much more scientifically sound than those in the past.  And while it was still not until recently that AD was officially declared its own disease separate from other forms of dementia, it was the 70s in which dementia was finally indentified as a disease, and thus the rush began to find ways to prevent and cure it.

Look back tomorrow for Part II: Drug Treatments Flourish – then Flounder