Study Finds About Half of Alzheimer’s Cases Are Mild

More than six million Americans are living with Alzheimer’s, a number that is expected to more than double over the next 30 years. With no cure, it can be overwhelming to face such a diagnosis. However, a new study finds that most cases of Alzheimer’s are not severe, giving hope that there may be more opportunities for early intervention.

Researchers from Boston University examined the health information of more than 17,000 people from the Framingham Heart Study, which has followed thousands of people over decades, dating back to 1948. By looking at figures collected between 2004 and 2009, the team discovered that about half of Alzheimer’s cases are mild. Their findings were published January in the Journal of Alzheimer’s Disease.


The study authors say this was a unique project, explaining, “Studies providing Alzheimer’s disease (AD) prevalence data have largely neglected to characterize the proportion of AD that is mild, moderate, or severe. Estimates of the severity distribution along the AD continuum, including the mild cognitive impairment (MCI) stage, are important to plan research and allocate future resources, particularly resources targeted at particular stages of disease.”

Among the 17,000-plus people whose medical information they studied, researchers found more than 1,000 with Alzheimer’s disease or mild cognitive impairment. Among them, 50.4% had mild disease, 30.3% had moderate disease, and 19.3% had severe disease. Of these 1,000 people, 29.5% had MCI that did not worsen with time, while 19.6% got worse and developed dementia.

Corresponding author Dr. Rhoda Au, professor of anatomy and neurobiology, says this information is important in determining how scientists can address the disease.


She explains, “Early intervention in MCI or the mild stage of AD dementia has been the primary focus for AD research and drug development in recent years. We found that approximately 45% of all those who are cognitively impaired or diagnosed with AD-dementia had early AD. Our results serve to inform the design of future research studies such as clinical and observational studies and provide optimal resource allocation for policy-making.”

Researchers said there were some limitations with their study, explaining the FHS does not necessarily reflect health in the United States as a whole. The pool is also limited, with all participants living in the same town and being predominantly white. There also wasn’t a biomarker test to confirm an Alzheimer’s diagnosis. Still, researchers say that because so many cases of Alzheimer’s and MCI were found to be mild, this may open up the possibility of more early intervention options and preserving quality of life longer.

Dr. Au says, “This means any drug treatment that is effective might help prevent their AD from getting worse.”


The researchers hope their work will lead to similar studies in a broader range of people so that quality of life can remain steady for more patients.

Some of the areas of focus for quality of life in Alzheimer’s patients are competent cognitive functioning, the ability to perform daily tasks and to engage in meaningful time use and social behavior, and a good balance between positive emotion and absence of negative emotion.

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