Two recent studies highlight the relationship between age and dementia, one finding that people with dementia survive an average of six years after their diagnosis, regardless of how old they are, and another reporting that the prevalence of dementia increases with age, even in the oldest population.
Data from the studies was presented at the 2018 Alzheimer’s Association International Conference recently held in Chicago.
Patients with dementia have a shorter life expectancy than the general population. Survival time after diagnosis varies considerably, with median survival times between three and 12 years. This variation could be due to many factors, including the type of dementia, patient characteristics and change in management over time.
Researchers at VU University Medical Center in Amsterdam analyzed the clinical records of 4,495 people enrolled in the Amsterdam Dementia Cohort between 2000 and 2014 who had subjective cognitive decline, mild cognitive impairment, or any type of dementia.
Their findings were published in the study, “Survival in memory clinic cohort is short, even in young-onset dementia,” in the Journal of Neurology, Neurosurgery & Psychiatry.
Patients who had frontotemporal lobar degeneration — degeneration of the frontal and anterior temporal lobes in the brain — survived a median 6.4 years. Those with Alzheimer’s disease survived a median 6.2 years and those with vascular dementia — caused by the blockage of brain vessels — 5.7 years. Dementia with Lewy bodies was associated with a survival time of 5.1 years, and in rarer causes of dementia, 3.6 years.
“These findings suggest that, despite all efforts, and despite being younger and perhaps physically ‘healthier’ than older people, survival time in people with young-onset dementia has not improved since 2000,” Hanneke Rhodius-Meester, MD, PhD, the study’s author from the VU University Medical Center, said in a press release. “While these results still need to be replicated and confirmed, they do highlight the urgency of the need for better treatments and effective prevention strategies.”
Centenarians Have Increased Prevalence of Dementia
An analysis of 17 centenarian studies conducted across 11 countries through the International Centenarian Consortium for Dementia revealed that the prevalence of dementia is high in older people, even in the “oldest old” population.
The study, “100 Years and Beyond: Investigating the Prevalence of Dementia in Centenarians and Near Centenarians from 17 Population-Based Studies,” was presented by Yvonne Leung, PhD, a postdoctoral fellow from the Centre for Healthy Brain Ageing at the University of New South Wales in Sydney.
Upon analyzing the clinical records of 4,121 centenarians and near-centenarians — between 95 and 110 years old — researchers found that older people had a higher risk of dementia, as well as cognitive and functional impairments.
The prevalence of dementia was 35.96% among people ages 95-99 and increased up to 75.61% in people ages 105 or older. Similarly, the prevalence of cognitive impairment ranged from 45.24% to 78.72%, and functional impairment from 67.64% to 91.55%, as age increased.
The analysis also showed that the risk of dementia and cognitive and functional impairment varied considerably between countries. This suggests that cultural and lifestyle factors play an important role in remaining physically and mentally healthy as people age.
Participants who had higher levels of education had a lower prevalence of dementia and cognitive impairment. Additionally, near-centenarian and centenarian women had a higher risk of dementia and cognitive impairment than men.
“This is the first study to define the global prevalence of dementia in this advanced age group using a set of common diagnostic criteria,” Leung said. “These data, and this type of research, may help identify protective factors to reduce the risk of dementia, and provide insights into longevity and brain health.”