The more chronic ailments we’re plagued by later on in life, the more susceptible we are to developing mild cognitive impairment (MCI) and dementia, a recent study published in the Journal of the American Geriatrics Society has found.

Studying 2,176 cognitively normal adults from the ages of 70 to 89, the authors found that individuals with more than one chronic illness such as diabetes, arthritis, or hypertension were more likely to go on to develop cognitive impairments than those with one or no chronic condition. The effect also appears to be cumulative in terms of both age and frequency, with older adults and those with four or more chronic conditions at greater risk.

“These findings emphasize the importance of preventing and effectively managing chronic diseases, provide added insights into contributors of risk for MCI and dementia, are consistent with the hypothesis that multiple etiologies may contribute to MCI and late-life dementia, and have important implications for healthcare planning and developing strategies to reduce the burden of MCI and dementia,” the authors wrote.

The researchers focused on a random sample of individuals from Olmsted County, Minnesota who were enrolled in the Mayo Clinic Study of Aging (MCSA), a prospective population-based cohort study that has attempted to map out the prevalence, incidence and risk factors for MCI and dementia. These participants were given “comprehensive in-person evaluation including the Clinical Dementia Rating Scale, a neurological evaluation and neuropsychological testing,” and followed up with every 15 months. Though the MCSA study first began in 2004, there were additional recruitment drives annually from 2008 to 2011.

In this current study, the authors only examined those participants who originally tested — in person — as cognitively normal and had at least one follow-up evaluation. The average age of their study sample was 78.5 years and they remained willing participants for a median length of four years. A whooping 86.6 percent had at least two or more chronic conditions — defined as multimorbidity by the authors — out of a list of 17, which additionally included asthma, coronary artery disease (CAD) and substance abuse disorders.

Though the mere presence of multimorbidity increased the risk of someone developing MCI and dementia, with an average increased risk of 38 percent compared to those with one or no conditions, there were certain pairs that were especially hazardous. These included hypertension and hyperlipidemia (high levels of lipids or fats in the blood), hypertension and arthritis, and hypertension and CAD — living with these conditions left participants around 50 percent more likely to develop MCI and dementia. In total, 583 participants developed MCI or dementia over the length of the study period.

While the researchers are confident about the link between chronic illness and cognitive impairment, they’re less certain about why it occurs. They do, however, offer some theories.

“An important potential mechanism is through cardiovascular diseases: hypertension, hyperlipidemia, and cardiac diseases, specifically CAD,” they wrote. “A second potential mechanism is aging, an important risk factor for many chronic diseases”

Likewise, it might be the case that chronic conditions like arthritis limit mobility and physical activity, thus leaving people more susceptible to cardiovascular disease, which in turn speeds along MCI; or that people with concurring chronic conditions are more likely to have harmful interactions with their increasing stockpile of medications.

Whatever the reason(s), the authors hope their findings can encourage health professionals to proactively reach out to vulnerable populations.

“Preventing chronic diseases may be beneficial in delaying or preventing MCI and dementia,” they concluded.

Source: Vassilaki M, Aakre M, Cha R, et al. Multimorbidity and Risk of Mild Cognitive Impairment. Journal of the American Geriatrics Society. 2015.