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New study challenges accepted approaches to
research in senile dementia (Alzheimer's
disease)
November 7, 2011 -- Impacting millions of
families and devouring billions of dollars
globally, Alzheimer's disease is the focus
of exhaustive research to find a cure.
Although intensely investigated over the
last three decades using cutting-edge
technologies, the "pathogenic cause" of
Alzheimer's disease has not been found.
While many research "breakthroughs" have
been claimed and high-profile drugs trials
carried out, why does the promised "cure"
still seem to elude scientists?
In an effort to address this question, Ming
Chen, PhD, Huey T. Nguyen, BS, and Darrell
R. Sawmiller, PhD, Aging Research
Laboratory, R&D Service, Bay Pines VA
Healthcare System and University of South
Florida, undertook an independent and
systematic analysis of the underlying
research assumptions against the established
scientific principles. This analysis led
them to hypothesize that perhaps the main
problem is the research community's
perception of the disease.
In an article scheduled for publication in
the December issue of the Journal of
Alzheimer's Disease the authors suggest
that when the National Institutes of Health
separated out dementia from other senile
conditions and redefined it as a distinct
and "curable" disease -- Alzheimer's – in
the 1970s, it opened a Pandora's box and may
have misdirected research for decades. It
triggered the search for pathogenic factors
and cures, and disregarded the role of
demographic change and its diverse end
results in the elderly.
The authors argue that senile disorders –
diseases occurring after age 60 and
eventually affecting the majority of the
elderly, such as tooth, hearing or memory
loss – are caused by aging, thus differ
fundamentally from distinct diseases by
origin, study paradigm and intervention
strategy.
Moreover, the authors contend that a central
regulator in cognition − the Ca2+ signaling
system − has been misconceived by
institutional thinking that favors a "cure"
for senile dementia. The dominant
hypothesis, although unproven, is that Ca2+
levels rise throughout the aging process,
leading to cell death, and thus research has
focused on calcium antagonists to lower
those levels. This viewpoint has been
promoted by policy makers, and the subject
of a number of high profile clinical trials,
but to date no positive results have
emerged.
In contrast, the authors propose that
declining functionality of Ca2+ signaling as
a result of the aging process, among a
myriad of other age-related changes, leads
to cognitive decline. Therefore
Interventions for senile dementia could
activate Ca2+ function by promoting energy
metabolism and also by Ca2+ agonists such as
caffeine and nicotine. At the same time,
risk factors play a key role.
"Aging and Ca2+ deficits set the stage for
senile dementia, but do not always lead to
senile dementia in real life," explains Dr.
Chen. "Lifestyles and other risk factors are
the key. So we think that senile dementia
may be explained by 'advanced aging plus
risk factors.' This model points to a new
direction for prevention. This means we must
support the elderly in healthy lifestyles.
And we should develop medications to extend
the lifespan of old neurons, rather than
looking for ways to inhibit far-fetched
'pathogenic' factors."
"The model implies that senile dementia is,
by and large, a lifestyle disease," says Dr.
Chen. "This view, in fact, has been shared
by many in the medical and clinical
community, but contrasts sharply with
current dominant theories in the Alzheimer
research field, which assume a linear and
'cause and effect' mechanism. Since they
have not taken into account the fundamental
roles of aging and risk factors, it is clear
that these theories, though highly appealing
to the public and researchers alike, are of
little relevance to the scientific nature of
senile dementia."
"The two overwhelming concepts, senile
dementia as a distinct disease and the Ca2+
overload hypothesis, have effectively
blocked any meaningful progress in senile
dementia research, and have inhibited the
self-correcting mechanism of science,"
concludes Dr. Chen. "An independent scrutiny
on the field may be helpful."
"Although incurable", Dr. Chen is
optimistic. "Our research, if guided by
correct theories, will produce medications
to help delay dementia to a certain extent −
similar to the drugs that delay or
ameliorate atherosclerosis and osteoporosis
today."