Posts Tagged Aging
New research shows that Alzheimer’s disease hits people in their 60s and 70s harder than people who are 80 years and older.
Researchers at the University of California, San Diego School of Medicine note that the greatest risk factor for Alzheimer’s is age. In fact, by the age of 85, the likelihood of developing the dreaded neurological disorder is roughly 50 percent, they say.
But in their study, they found that the “younger elderly” — those in their 60s and 70s — showed higher rates of cognitive decline and faster rates of tissue loss in brain regions that are vulnerable during the early stages of Alzheimer’s, according to Dominic Holland, Ph.D., a researcher in the Department of Neurosciences at UC San Diego and the study’s first author.
“Additionally cerebrospinal fluid biomarker levels indicate a greater disease burden in younger than in older individuals,” he said.
Holland and his colleagues, using imaging and biomarker data from participants in the Alzheimer’s Disease Neuroimaging Initiative, examined 723 people, ages 65 to 90 years, who were categorized as either cognitively normal, with mild cognitive impairment (an intermediate stage between normal, age-related cognitive decline and dementia) or suffering from full-blown Alzheimer’s disease (AD).
The findings have implications for diagnosing the disease — which currently afflicts an estimated 5.6 million Americans, a number expected to triple by 2050 — and efforts to find new treatments, the researchers said.
At present, there is no cure for Alzheimer’s and existing therapies do not slow or stop the disease’s progression.
A key feature in the diagnosis of Alzheimer’s is its “relentless progressive course,” Holland said.
“Patients typically show marked deterioration year after year. If older patients are not showing the same deterioration from one year to the next, doctors may be hesitant to diagnose AD, and thus these patients may not receive appropriate care, which can be very important for their quality of life.”
Holland said it’s not clear why the disease is more aggressive among the younger elderly.
“It may be that patients who show onset of dementia at an older age, and are declining slowly, have been declining at that rate for a long time,” added co-author Linda McEvoy, Ph.D., associate professor of radiology. “But because of cognitive reserve or other still-unknown factors that provide ‘resistance’ against brain damage, clinical symptoms do not manifest till later age.”
Another possibility is that older patients may be suffering from mixed dementia — a combination of Alzheimer’s and other neurological conditions, Holland said. These patients might withstand the effects of Alzheimer’s until other adverse factors, such as brain lesions caused by cerebrovascular disease, take hold. At that time, Alzheimer’s can only be definitively diagnosed by an autopsy, he said.
Clinical trials to find new treatments for the disease may be affected by the differing rates of progression, researchers said.
“Our results show that if clinical trials of candidate therapies predominately enroll older elderly, who show slower rates of change over time, the ability of a therapy to successfully slow disease progression may not be recognized, leading to failure of the clinical trial,” said Holland. “It’s critical to take into account age as a factor when enrolling subjects for AD clinical trials.”
While the obvious downside of the findings is that younger patients with Alzheimer’s lose more of their productive years, “the good news in all of this is that our results indicate those who survive into the later years before showing symptoms of AD will experience a less aggressive form of the disease,” Holland concluded.
The research appears online in the journal PLOS One.
In a new area of study, researchers explore how brain mechanisms for memory retrieval differ between adults and children.
Neuroscientists from Wayne State University and the Massachusetts Institute of Technology have discovered that while the memory systems are the same in many ways, the aging process appears to impart important differences in how we learn and respond to education.
Noa Ofen, Ph.D., an assistant professor in WSU’s Institute of Gerontology and Department of Pediatrics, says that cognitive ability, including the ability to learn and remember new information, dramatically changes between childhood and adulthood.
This ability parallels with dramatic changes that occur in the structure and function of the brain during these periods.
In the study, Ofen and her collaborative team tested the development of neural foundations of memory from childhood to young adulthood.
Researchers did this by exposing participants to pictures of scenes and then showing them the same scenes mixed with new ones. They then and asked them to judge whether each picture was presented earlier.
Participants made retrieval judgments while researchers collected images of their brains with magnetic resonance imaging (MRI).
Using this method, the researchers were able to see how the brain remembers. “Our results suggest that cortical regions related to attentional or strategic control show the greatest developmental changes for memory retrieval,” said Ofen.
This finding suggests that older participants use the cortical regions of the brain to retrieve past memories more so than younger participants.
“We were interested to see whether there are changes in the connectivity of regions in the brain that support memory retrieval,” Ofen added.
“We found changes in connectivity of memory-related regions. In particular, the developmental change in connectivity between regions was profound even without a developmental change in the recruitment of those regions, suggesting that functional brain connectivity is an important aspect of developmental changes in the brain.”
Researchers say this study is unique as it is the first time that the development of connectivity within memory systems in the brain has been tested.
Findings suggest the brain continues to rearrange connections to achieve adult-like performance during development.
Future studies by Ofen and her research team will focus on modeling brain network connectivity, and applying these methods to study abnormal brain development.
The team’s findings are published in the Journal of Neuroscience.
Source: Wayne State University