Key Highlights :
Alzheimer’s disease (AD) is a progressive neurological disorder that is the leading cause of dementia in the elderly. It has a significant impact on the quality of life of those affected, resulting in a loss of independence, productivity, and health. To better understand the expected survival of people at each stage of AD, a recent study published in BMC Neurology analyzed the increase in mortality risk at each stage from baseline mortality in people without cognitive impairment.
The study, titled Disease severity and mortality in Alzheimer's disease: an analysis using the U.S. National Alzheimer’s Coordinating Center Uniform Data Set, was a retrospective study that included over 12,000 people in the United States aged 50 and older with mild to severe cognitive impairment due to AD. The data was obtained from the Uniform Data Set (UDS) of the National Alzheimer’s Coordinating Center (NACC).
The participants were classified as being cognitively normal (CN), AD with mild cognitive impairment (MCI), or AD dementia. The mean follow-up in each group was about four years, four years, and two to three years, respectively. The mean ages were higher in each of the AD cohorts as compared to the CN cohorts. The majority of participants were female (two out of three) and White of non-Hispanic origin (three out of four).
The study found that people with AD who developed MCI or with dementia due to AD lived for a median of three to 12 years. Most AD patients with severe dementia died before the end of the study period. The mortality rate increased with the severity of dementia, especially in patients of a younger age. People 65 years or older with more severe disease were seven-fold more likely to die early. When assessed at 80 years, the risk of mortality was raised by 2.4-6.6-fold with increasing severity, thus indicating that younger participants showed a higher effect of AD severity on the risk of death.
Certain factors, such as being a male, having severe AD, and a history of other illnesses like diabetes, hypertension, and ischemic heart disease or stroke, also affected the mortality risk of AD. Other factors that impacted AD-related mortality included White ethnicity, low educational status, and low body mass, as well as being positive for apolipoprotein E ε4 in men.
The study also found that patients were more likely to die if they were older, male, lived in long-term care homes or institutions and were current smokers, alcoholics, or ever had ischemic heart disease. Being underweight or normal weight was also a risk factor, while White or Hispanic or Latino participants were at higher risk compared to Asians or non-Hispanic/Latinos.
Overall, the study concluded that people with more severe AD are more likely to die early, with this disproportionately affecting younger individuals with AD. However, AD-MCI does not appear to carry a similar increase in risk unless it progresses to more severe cognitive impairment. The findings suggest that if preventive and therapeutic interventions are successful in preventing or delaying the progression of AD, there may be a benefit of lower mortality, particularly in relatively younger people.
The authors of the study suggest that future studies should focus on a more general study population and should consider the confounding effects of age and severity of AD when assessing the efficacy of any proposed therapy. Measures aimed at reducing the risk of daily death by slowing down or preventing the progression of AD must be evolved through clinical trials in order to improve the quality of life for those living with Alzheimer's disease.