Multiple Risk Factors for Late-Life Dementia Identified

Lara C. Pullen, PhD

October 04, 2012

October 4, 2012 (Rochester, Minnesota) — The Mayo Clinic Study of Aging has identified multiple risk factors for late-life brain pathology. Vascular risk factors, high caloric intake, and being positive for apolipoprotein E (APOE) ε4 all increase the odds of cognitive impairment.

Rosebud O. Roberts, MB, ChB, of the Mayo Clinic in Rochester, Minnesota, presented the results of one study and coauthored another study analyzing risk factors for brain pathology in late life. The 2 studies were presented in poster form at the first Individualizing Medicine Conference, which was held at the Mayo Clinic.

The vascular analysis included 1452 participants with a median age of 80 years. They underwent baseline structural MRI (sMRI) between August 2005 and September 2011.

Dr. Roberts and colleagues found a 4% reduction in hippocampal volume (HV) referenced to total intracranial volume in individuals with midlife type 2 diabetes (95% confidence interval [CI], 1% - 7%; P = .02). Dr. Roberts explained to Medscape Medical News, "We can see pathology in the brain that previously you could only detect from autopsy."

Dr. Roberts found that individuals with vascular risk factors in midlife are more likely to have sMRI abnormalities in late life. Late-life onset of vascular risk factors was not associated with sMRI abnormalities in late life.

Although vascular risk factors have long been associated with late-life brain pathology, this is the first study to indicate that the risk is associated only with midlife vascular risk factors. Dr. Roberts and colleagues propose that the vascular risk factors contribute to cognitive impairment in late life by inducing Alzheimer's disease pathology and brain vascular disease.

In the second study, mild cognitive impairment (MCI), particularly amnestic MCI, was found to be more common in individuals with high caloric intake and those who are APOE ε4+. MCI is the intermediate step between normal cognitive aging and dementia. MCI can be described as amnestic and nonamnestic, with amnestic MCI progressing to Alzheimer's disease.

This study included nondemented study participants, of whom 1072 were cognitively normal and 161 had MCI. Multivariable logistic regression analyses were conducted to compute odds ratio (OR) and 95% CI after adjusting for age, sex, education, depression, medical comorbidity, and body mass index.

The authors found that high caloric intake (>2143 kcals per day) was associated with an almost 2-fold increase in the odds of having MCI compared with the reference group (OR, 1.96; 95% CI, 1.26 - 3.06; P = .003). The authors suggest that this may provide a clue to understanding the pathophysiology of Alzheimer's disease.

Translating Genomics Into Patient Care

The inaugural Individualizing Medicine Conference focused on the incorporation of genomics into patient care. The inaugural conference had 5 themes: individualizing medicine, individualizing clinical care, individualizing laboratory medicine, ethical and regulatory implications of individualizing medicine, and decision-support infrastructure for individualizing medicine.

The Mayo Clinic Study of Aging was begun in 2004. It is a population-based cohort study of individuals in Olmsted County, Minnesota, aged 70 years and older. The study was designed to describe normal cognitive aging, MCI, and dementia.

Robert D. Brown Jr, MD, chair of the Department of Neurology at the Mayo Clinic, who is not associated with the Study of Aging, told Medscape Medical News that he is excited about its potential to analyze cognitive decline at the predisease state. He explained that "there is no question that this is really the hope of medicine in the future."

Dr. Roberts and Dr. Brown have disclosed no relevant financial relationships.

Individualizing Medicine Conference 2012. Abstracts 27 and 36. Presented October 1, 2012.