For people who develop Alzheimer’s disease before age 65, one of the hardest questions is how quickly the condition will take away their independence.
A new study suggests that a special measurement taken from routine brain scans may help provide a clearer answer. The tool tracks shrinkage in parts of the brain that are especially vulnerable to early-onset Alzheimer’s disease.
Early-onset Alzheimer’s is less common than Alzheimer’s that develops later in life, but its impact can be particularly disruptive. People may still be working, supporting children or caring for other family members when memory and thinking problems begin. Knowing roughly how quickly the disease may progress could therefore help families make financial, work and care plans earlier.
The disease often begins with mild cognitive impairment, commonly called MCI. People with MCI have noticeable problems with memory, language, reasoning or other thinking skills, but they can usually continue living independently. Some remain relatively stable for years, while others progress to dementia much more quickly.
That uncertainty is a major challenge for doctors and patients. Alexandra Touroutoglou of Harvard Medical School said one of the questions patients frequently ask is when they will lose their independence. Current clinical tests can identify thinking difficulties, but they have limited ability to predict the timing of future decline for an individual.
To address this problem, Touroutoglou and colleagues developed what they call an early-onset Alzheimer’s disease signature. It is not a blood test or a single spot in the brain. Instead, it is a pattern of shrinkage across several brain regions that are involved in important thinking abilities.
The researchers used magnetic resonance imaging, or MRI, which can produce detailed pictures of the brain without using radiation. They measured the thickness of gray matter in eight key regions. Gray matter contains large numbers of nerve cells and is essential for processing information.
The regions included areas involved in memory, language and reasoning, such as parts of the parietal and temporal cortex. These areas tend to become thinner as nerve cells and their connections are lost in Alzheimer’s disease. The researchers combined the measurements into a single score representing the overall degree of brain shrinkage.
The study included 130 people between ages 40 and 64 who were living independently with mild cognitive impairment, as well as 97 healthy people of similar ages. Participants received an MRI scan when they entered the study and returned for at least one annual follow-up visit. They were followed for an average of about two years.
During that period, approximately 65% of the participants with early-onset Alzheimer’s disease progressed from MCI to dementia. People whose initial scans showed more shrinkage in the Alzheimer’s-related brain regions tended to progress faster. For every one standard deviation increase in the amount of shrinkage, the risk of progressing to dementia was 1.24 times higher.
The brain measurement also predicted progression better than simply looking at the severity of a person’s symptoms when the study began. This is important because two people can appear to have similar memory or thinking problems while having different amounts of underlying brain damage. A scan-based measure could potentially add information that cognitive testing alone cannot provide.
If the approach is confirmed, it could have several practical uses. Doctors might be able to give patients and families a more individualized idea of how quickly the disease is likely to change. Researchers could also identify people who are likely to decline sooner and enroll them in clinical trials at an earlier stage, when treatments may have a better chance of helping.
The study was published in Neurology, the medical journal of the American Academy of Neurology. The authors describe the biomarker as a possible tool for estimating the pace of disease rather than simply identifying whether Alzheimer’s-related brain changes are present.
However, the findings are not yet precise enough to act as a countdown clock for an individual patient. A 1.24-fold increase in risk for each standard deviation of shrinkage describes a statistical relationship across the study population, not an exact date when a particular person will develop dementia. Alzheimer’s progression is influenced by many biological and health factors that a single scan cannot capture.
Another important limitation is that the biomarker was developed and tested within the same study group, and most participants were non-Hispanic white people.
Brain structure, health histories and access to care can differ across populations, so the tool needs independent testing in larger and more diverse groups. Longer follow-up will also be important because the average observation period was only about two years.
Overall, the study provides promising evidence that the pattern of gray matter loss may reveal more about the future course of early-onset Alzheimer’s than symptoms alone. Its greatest value may eventually be in combining brain imaging with cognitive tests, blood or spinal-fluid biomarkers and other information to make predictions more reliable.
For now, it is an encouraging research tool that could move Alzheimer’s care closer to answering not only what disease a person has, but how quickly it may change.
If you care about brain health, please read studies about vitamin D deficiency linked to Alzheimer’s and dementia, and strawberries can be good defence against Alzheimer’s.
For more health information, please see recent studies about foods that reduce Alzheimer’s risk, and oral cannabis extract may help reduce Alzheimer’s symptoms.
Source: Harvard Medical School.
