Obesity, Inflammation and Cognitive Decline

The rate of cognitive decline with aging is quite variable. 

Identifying important components of this process is needed for developing interventions to reduce the burden of Alzheimer's and other dementias.

Excess inflammation has been linked to obesity as well as aging-related cognitive decline.

Archana Singh-Manoux and colleagues recently published a study of the association between blood markers of inflammation and cognitive decline.

This study used data from the U.K. Whitehall II cohort, a group of men and women between the ages of 35-55 at intake.

This cohort has now been studied over a 20 year follow up with interval assessments about every five years.

Two blood markers of inflammation were studied in this cohort: interleukin-6 (IL-6) and C-reactive protein (CRP).

The study found strong associations between both blood markers of inflammation and rates of obesity (BMI >30) in the chart shown here.

Cognitive decline was measured by decrease scores on the Minimental Status Exam and other neuropsychological tests during the follow up period.

The primary finding from the study was that elevated IL-6 levels but not CRP levels at baseline were associated with accelerated cognitive decline.

Subjects in the highest IL-6 blood level group showed an 85% increased rate in losing 3 or more points on the Minimental Status Exam.

The authors note there study does not prove causality between IL-6 levels and cognitive decline but that:

"Inflammation is likely to play a role because of its impact on cerebral small-vessel disease, which could lead to changes that affect cognitive ageing."

It is also possible, that some of the link between obesity and cognitive decline may be attributable to increased obesity-related inflammation.

The practical clinical potential would be to attempt to identify and reduce inflammation in those most at risk. Anti-inflammatory drugs such as naproxen (Aleve in U.S.) have not been generally effect in trials to reduce rates of Alzheimer's disease.

However, these trials have typically not targeted groups with the highest blood markers of inflammation.

Readers with more interest in this topic can access the free full-text manuscript by clicking on the link in the citation below.

Photo of great blue heron from South Padre Island, TX is from the author's files.

Chart is an original figure from data abstracted from the manuscript.

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Singh-Manoux A, Dugravot A, Brunner E, Kumari M, Shipley M, Elbaz A, & Kivimaki M (2014). Interleukin-6 and C-reactive protein as predictors of cognitive decline in late midlife. Neurology, 83 (6), 486-93 PMID: 24991031