WASHINGTON, DC—Among older adults, having multiple chronic conditions is associated with an increased risk of developing mild cognitive impairment (MCI) or dementia, according to data presented at the 67th Annual Meeting of the American Academy of Neurology. This finding is consistent with the hypothesis that several etiologies may contribute to MCI and late-life dementia. “Preventing chronic diseases may be useful in delaying or preventing MCI or dementia,” said Maria Vassilaki, MD, PhD, a neurologist with Mayo Clinic in Rochester, Minnesota.
Population-Based Study
Multimorbidity, which is defined as the coexistence of two or more chronic conditions in an individual, is highly prevalent among older adults. It is associated with an increased risk of disability, functional decline, premature death, and increased use of emergency care. Multimorbidity may contribute to increased risk of MCI, but the association had not been investigated comprehensively in a population-based setting, said Dr. Vassilaki.
She and her colleagues conducted a prospective study of 2,174 cognitively normal people enrolled in the Mayo Clinic Study of Aging in Olmsted County, Minnesota. Participants were age 70 or older at baseline and were recruited randomly from the community. Participants underwent a clinical evaluation at baseline and at 15-month intervals to determine diagnoses of MCI and dementia. The researchers captured information on International Classification of Diseases, ninth revision codes for chronic conditions in the five years before enrollment electronically using the Rochester Epidemiology Project medical records linkage system.
Severe multimorbidity was defined as having four or more chronic conditions. The investigators examined chronic diseases such as hyperlipidemia, hypertension, depression, coronary artery disease, obstructive pulmonary disease, and stroke. They analyzed the association between multimorbidity and MCI or dementia using Cox proportional hazards models adjusted for sex and education.
Participants’ mean age was 78.5, and 50.6% of the population was male. In all, 1,684 study participants (77.5%) had multimorbidity. There were no differences by sex in the frequency of multimorbidity or severe multimorbidity. During the median four years of follow-up, 583 participants developed incident MCI or dementia.
Age and Multimorbidity Were Risk Factors
Overall, the risk of MCI or dementia was elevated in persons with multimorbidity (hazard ratio [HR], 1.47). The risk did not vary by gender, but the association did not reach statistical significance for women. Participants with severe multimorbidity had a greater risk of MCI or dementia (HR, 1.6). The investigators found no statistically significant interactions between multimorbidity and gender in regard to the risk of MCI. They found an increase in the risk of MCI with increasing age and multimorbidity.
Potential mechanisms by which multimorbidity may increase the risk of MCI or dementia include aging, cardiovascular disease, and failure to manage several chronic conditions optimally, said Dr. Vassilaki. The study underscores the importance of preventing chronic disease and, when prevention fails, managing it effectively, she concluded.
—Erik Greb