Detection of dementia at the earliest stages has become a worldwide scientific priority because drug treatments, prevention strategies and other interventions will likely be more effective very early in the disease process, before extensive brain damage has occurred.
Peter Sayer, Alison Bloomer, and Eve Batt report from the Alzheimer’s Association International Conference 2017 (AAIC).
Research results provided clues about associations between cognitive status in older people and several behaviour and lifestyle factors, including verbal skill, hearing, and hospitalisation.
“It is essential that we learn more about factors that indicate or impact risk for Alzheimer’s disease and other dementias, especially lifestyle factors that we can change or treat,” said Maria C. Carrillo, PhD, Alzheimer’s Association Chief Science Officer. “The Alzheimer’s Association is committed to advancing scientific research to identify simple and accessible ways to spot the signs of cognitive decline.”
Hearing loss is associated with poor cognition and progression to mild cognitive impairment
Taylor Fields, a doctoral student in the Neuroscience Training Program within the University of Wisconsin School of Medicine and Public Health, and colleagues examined the prevalence of hearing loss in late middleaged adults with a family history of Alzheimer’s, and the association between hearing loss and cognitive status and decline. The researchers found evidence for a link between hearing loss and mild cognitive impairment, a condition that can be a precursor to Alzheimer’s disease.
The scientists used data collected from 783 people enrolled in the Wisconsin Registry for Alzheimer’s Prevention (WRAP), a longitudinal study group of people with a parental history of Alzheimer’s. Participants undergo periodic tests to evaluate their ability to remember, process, and learn information. Study volunteers self-reported whether they had been diagnosed with hearing loss. At the beginning of the study, all volunteers had normal test results for clinical tests of cognitive function, and all were assessed for progression to mild cognitive impairment.
Over the course of four years, 72 (9.2%) study participants reported being diagnosed with hearing loss. Relative to those who reported normal hearing, people in the study with hearing loss were:
nnMore likely to score significantly poorer on cognitive tests such as how quickly new information is processed, flexibility in thinking, and how the brain, eye, and hand coordinate during information processing.
nnRoughly three times as likely to be characterised as having mild cognitive impairment.
“This study suggests that hearing loss could be an early indicator of worsening cognitive performance in older adults,” Fields said. “Identifying and treating hearing loss could have value for interventions aimed at reducing the burden of Alzheimer’s disease.”
Emergency and urgent hospitalisations related to accelerated cognitive decline in older people
Research shows that older adults are at high risk for memory and other cognitive problems after being hospitalised, not only transient delirium but also longterm changes in cognition. However, it is unknown whether elective hospitalisations, such as for scheduled surgery, put older individuals at the same risk for faster cognitive decline as emergency or urgent admissions (nonelective hospitalisations).
In research reported at AAIC 2017, Bryan James of the Rush Alzheimer’s Disease Center at Rush University Medical Center in Chicago, Illinois, USA, and colleagues found that non-elective hospitalisations were associated with acceleration in cognitive decline from prehospital rates, but elective hospitalisations were not associated with a change in the rate of cognitive decline. Data came from 930 older adults (75% female, mean age of 81 years old) enrolled in the Rush Memory and Aging Project (MAP) in Chicago. The study involved annual cognitive assessments, as well as clinical evaluations. Information on hospitalisations was acquired by linking 1999–2010 Medicare claims records for these participants to their MAP data. All hospital admissions were designated as elective, emergency, or urgent (the latter two combined as nonelective for analysis).
Of the 930 participants, 613 were hospitalised at least once over an average of almost five years of observation. Of those who were hospitalised, 260 (28%) had at least one elective hospital admission, and 553 (60%) had at least one non-elective hospital admission; 200 participants (22%) had both types of hospitalisations. In a model adjusted for age, sex, education, self-reported chronic medical conditions, length of stay, surgeries, intensive care unit stays, and comorbidities, non-elective hospitalisations were associated with acceleration in the rate of cognitive decline from before hospitalisation, while elective hospitalisations were not. Non-elective hospitalisations were associated with an approximately 60% acceleration in the rate of decline.
“We saw a clear distinction: non-elective admissions drive the association between hospitalisation and long-term changes in cognitive function in later life, while elective admissions do not necessarily carry the same risk of negative cognitive outcomes,” James said. “These findings have important implications for the medical decision making and care of older adults. While recognising that all medical procedures carry some degree of risk, this study implies that planned hospital encounters may not be as dangerous to the cognitive health of older persons as emergency or urgent situations.”