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.Follow me on Twitter WRY999
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
I have previously published several posts related to diet, cardiovascular mortality and cognitive function. A recent post looked at the relationship of fiber intake and mortality. Another post examined adherence to a Mediterranean style diet with reduced risk of cognitive decline. Now there is another important study published examining diet and risk of cardiovascular mortality and all-cause mortality. Cardiovascular disease and mortality are important issues for many of the clinical neuroscience diseases. Heart disease is often the first issue that comes to mind when thinking about cardiovascular disease. However, here is just a partial list of clinical neuroscience disorders linked to vascular function and health:- Stroke
- Vascular and Alzheimer's dementia
- Transient ischemic attacks
- Vascular neuropathy
A study Akbaraly et al published in The American Journal of Clinical Nutriton examined dietary history and mortality in those participating in the Whitehall II epidemiologic study. The Whitehall II study is a study of Londoners who worked in one of 20 civil service occupations. The baseline data was first collected in 1985 through 1988 (when subjects were 35 to 55 years old) but nutritional information was not collected until 1991-1993. At that time subjects were scored on a composite index of healthy eating called the Alternative Healthy Eating Index (AHEI) composed of the following subscale categories:- Vegetables
- Fruits
- Nuts and soy
- Ratio of white meat to red meat
- Total fiber
- Trans fat
- Ratio of unsaturated fats to saturated fats
- Duration of multivitamin use
- Alcohol intake
A composite score is calculated from this index with higher scores indicating presumed healthier diet. The study subjects were grouped in three groups--low AHEI , intermediate AHEI and high AHEI each group representing a third of the sample.
After 18 years of follow up, approximately 10% of the low AHEI subjects had died compared to 7% of the high AHEI subjects. Cardiovascular mortality was 42% less for those in the high AHEI group. All estimates were made after controlling for a variety of potential confounding sociodemographic variables, i.e. gender, BMI, smoking status).
There were two findings that caught my attention from this study. One was some of the inflammatory and clinical differences in the groups. The high AHEI group:- Had lower serum levels of inflammatory markers C-reactive protein (CRP) and interleukin-6 (IL-6)
- Had lower levels of dyslipidemias (elevated cholesterol or triglycerides)
- Had no lower risk of having hypertension or diabetes
A second finding in the study was the examination of the contribution of individual categories to correlation with lower cardiovascular mortality risk. Only two of the categories correlated with reduced cardiovascular death rates: nuts and soy AHEI scale score and alcohol intake scale score. Total fiber intake had the next largest individual contribution but failed to be statistically correlate with reduced mortality.
Maximum scores in the nuts and soy category were reached with only one serving per day. Maximum scores in the alcohol intake category were reached with two drinks per day for men and one drink per day for women.
This study adds impetus to further study of what are the most important contributing factors of a "healthy diet" when health is measured as reduce risk of mortality from cardiovascular disease and all other causes.
Photo of Carlos Zambrano pitching for the Chicago Cubs courtesy of Yates Photography. Akbaraly TN, Ferrie JE, Berr C, Brunner EJ, Head J, Marmot MG, Singh-Manoux A, Ritchie K, Shipley MJ, & Kivimaki M (2011). Alternative Healthy Eating Index and mortality over 18 y of follow-up: results from the Whitehall II cohort. The American journal of clinical nutrition, 94 (1), 247-53 PMID: 21613557
