New research indicates that frailty makes older adults more prone to
dementia and Alzheimer's disease, and moderates the effects of dementia-related
brain changes on symptoms of dementia.
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| High levels of frailty may develop Alzheimer's dementia |
Frailty could make people more susceptible to develop the risk of Alzheimer's dementia
More
recently, a study report has been published in the journal“The Lancet
Neurology” that is referred to show the relationship between frailty
and dementia risks or Alzheimer's disease biomarkers.
The research
report suggests that high levels of frailty may develop
the symptoms and risks of dementia.
Older adults
with physical fragility are more susceptible to develop Alzheimer's
dementia and more likely to have brain changes associated
with Alzheimer's disease.
Physical
fragility or frailty is a condition which is linked to reduced
physiological or low physical reserve and increased vulnerability to other
diseases.
It is also
related to age, higher rates of dementia and cognitive deficits, but
lately, small research has discovered how these conditions can be
related.
The physical
fragility or frailty should be considered in the management of Alzheimer's
dementia and clinical care.
High levels of frailty may
develop Alzheimer's dementia
In the
study, researchers have found that frailty makes older people (59
years and older) more susceptible to have Alzheimer's disease-related
brain changes on dementia symptoms, while others with significant brain
changes, but who were not frail, have fewer clinical signs and symptoms.
Lead author,
Kenneth Rockwood, a professor at Nova Scotia Health Authority and Dalhousie
University, Canada, explained key points of the study report in his statement
and said
“By limiting
the physiological reserve of the individual, frailty can lead to a clinical
expression of dementia when it may remain non-accidental or asymptomatic in a
person who is not frail.
This
suggests that a 'frail brain' may be more prone to neurological problems such
as dementia because it is less able to handle the disease burden.
This is a
huge step in Alzheimer's research in the right direction.
Our findings
indicate that the symptoms of dementia are caused by several factors, and brain
changes associated with Alzheimer's disease are likely to be only one factor in
a whole series of events that cause clinical symptoms.
Understanding
and remembering how an individual's risk factors work together to elicit
late-life dementia and are more likely to provide a new technique to develop
targeted treatment options”.
The
conclusions of the study support that the late-life dementia is a complex
phenomenon (especially in the case of Alzheimer's disease) rather than a single
pathogen or genetic risk or a single protein defect in the brain.
However, the
authors have warned that the study is a cross-sectional comparison of pathology
data from a single database of adults living in Illinois, USA.
In the
previous research, it had been shown that some people with brain changes
associated with Alzheimer's disease (such as an amyloid deposition) may have
few distinct symptoms of the disease (functional and cognitive decline), while
others with few brain changes may have symptoms of dementia.
This
discrepancy reveals that some hidden factors may affect the relationship
between brain changes associated with Alzheimer's disease and Alzheimer's
dementia.
Most people,
who develop Alzheimer's dementia and have many other health problems, are more
than 65 years old.
In this
research, the researchers used modeling to assess the relationships between
Alzheimer's dementia, Alzheimer's disease-related brain changes and frailty
(vulnerability) among 456 participants of the Rush Memory and Ageing Project
(MAP) who died and underwent brain autopsy or brain dissection and who had
either no dementia or Alzheimer's dementia.
Memory and
Ageing Project (MAP) is a longitudinal clinical-pathological study initiated in
1997 for older people living in Illinois, USA.
Every year,
participants received neurological assessments and clinical evaluations,
including detailed neurological examinations and cognitive tests.
The clinical
diagnosis of Alzheimer's disease was based on the consensus of physicians, with
just over half (53 percent; 242) giving participants a diagnosis of possible
Alzheimer's disease in the recent clinical evaluation.
Brain
plaques, aggregates, and tangles were measured after death to determine changes
related to Alzheimer's disease. Researchers also developed a frailty index and
discovered a brittle index using a combination of 41 components of the health
status (for example, stress, joint and heart problems, fatigue, osteoporosis,
meal preparation, and mobility) obtained in each clinical evaluation.
Altogether,
there was considerable change in the brain related to Alzheimer's disease.
Overall, 8% of participants (35 people) had significant Alzheimer's
disease-related brain changes without being diagnosed with dementia, and 11 %(
50 people) had Alzheimer's dementia but had few brain changes associated with
the disease.
The analysis
showed that Alzheimer's disease-related brain changes and frailty independently
contribute in the case of dementia, after adjusting for sex, age and
education.
Researchers
have also found an important link between frailty and brain changes related to
Alzheimer's disease, after excluding daily activities from the frailty index
and adjusting for other risk factors such as heart failure, stroke, diabetes,
and high blood pressure.
While
frailty is likely to contribute to other mechanisms in the body that lead to
dementia, it probably also reduces the threshold of brain changes
associated with Alzheimer's disease to cause cognitive decline, weakening
the direct link between dementia and brain changes related to Alzheimer's
disease.
Whereas more
research is needed since frailty can be reversed, it is possible that by
helping people to maintain work and independence in later life, the severity of
debilitating symptoms and dementia risk both can usually be reduced in this
disease”, says Rockwood.
Dr.
Francesco Panza from the University of Bari Aldo Moro, Italy, commented how
understanding frailty can help indicate and prevent dementia, "In light of
current knowledge on Alzheimer's dementia and cognitive frailty phenotype,
secondary preventive strategies for physical frailty and cognitive impairment
may be suggested.
For example,
personalized multimedia or individualized multi-domain interventions can target
nutritional, physical, psychological and cognitive domains, which can delay the
progression to overt dementia and secondary events of adverse health-related
consequences such as hospitalization, mortality, and disability.
Conclusion
In this
research, the authors of the study said future studies should examine the
longitudinal relationships between vulnerability, frailty and cognition
and the vital signs of Alzheimer's disease to determine the causal relationship.
They noted
many limitations, including that not even a single definition of frailty has
been established well - some definitions are more physical, others are more
biological, while some biological, physical, social and psychological risks
factors can be combined.
They also
noticed that the frailty measurement was taken closer to death and could
reflect the terminal decline, resulting in the relationship between dementia
status and Alzheimer's disease-related brain changes among people with high
levels of physical fragility and frailty.
Journal
Reference: The Lancet Neurology, 2019 DOI: 10.1016/S1474-4422(18)30371-5
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Source: ScienceDaily, January 2019. Frailty could make people more susceptible to dementia