Chronic inflammation in middle age may be linked to an increased risk of frailty and overall poorer health decades later, a new study suggests.

Overall for the study sample, each standard deviation of higher inflammation recorded in mid-life yielded a 39 per cent higher odds of frailty approximately 24 years later, the researchers said. The prevalence of frailty in later life among people who had low levels of inflammation throughout mid-life was four to five per cent. However, the prevalence of later life frailty among adults with high levels of inflammation during mid-life was nine per cent -- approximately double.

"Middle adulthood may be an especially important period for poor health in older adults for multiple reasons. First, it is in middle age when the incidence of common chronic diseases, such as diabetes, begins to accelerate," said lead author Keenan Walker, from the Johns Hopkins University School of Medicine. "Second, compared to individuals who develop systemic disease and inflammation in later life, individuals who develop these conditions in mid-life may have a longer exposure and therefore are more susceptible to deleterious physiological effects," Walker added.

For the study, published in The Journal of Gerontology, the research team analysed data from 5,760 adults in their 70s. The participant's health has been followed over the course of five medical examinations, starting in 1987-1989, when they were in their 40s and 50s. The fifth and most recent medical visit and evaluation occurred in 2011-2013. The investigators specifically examined measures of five markers of inflammation in the bloodstream collected during participant's initial study visits.

Inflammatory biomarker levels were combined to create an inflammation composite score, which was used as a marker of each participant's overall level of inflammation. Next, all participants who completed the fifth visit were categorised as frail, pre-frail or robust depending upon how many of the following attributes they had at the time -- exhaustion, slowness, low physical activity, weakness and weight loss. Those deemed frail met three or more of these criteria, while those categorised as pre-frail met one or two of the criteria, and those categorised as robust met none of the criteria.