Weight Loss Between Mid-Life and Late Life May Signal MCI

February 04, 2016

New findings suggest that an increasing rate of weight loss over decades from mid-life to late life may help identify persons at increased risk for mild cognitive impairment.

The study, published online in JAMA Neurology on February 1, was conducted by a team led by Rosebud O. Roberts, MB, Mayo Clinic, Rochester, Minnesota.

"Several previous studies have shown that weight loss is associated with dementia, but we wanted to see if it was also associated with mild cognitive impairment," Dr Roberts explained to Medscape Medical News. "We did indeed find a clear relationship between the rate of weight loss between mid-life and late life and risk of mild cognitive impairment, suggesting that weight loss during this period could be a marker for future cognitive issues. This has implications for preventive strategies for cognitive impairment."

Dr Rosebud O. Roberts

She acknowledged that because it is not known whether this is a causal relationship, it is difficult to make specific recommendations based on these findings. But she suggested that if an older patient has unexplained weight loss, "it might be worth just monitoring their cognition and advising lifestyle changes that are thought to preserve cognition, such as healthy diet and exercise."

For the study, the researchers followed 1895 cognitively healthy participants aged 70 years or older and evaluated cognition at baseline and every 15 months for an average of 4.4 years. They also retrospectively obtained their maximum weight values at mid-life using a medical records–linkage system.

Over the 4.4-year follow-up period, 524 of the 1895 individuals developed mild cognitive impairment. The mean rate of weight change per decade from mid-life to study entry was greater for participants who developed mild cognitive impairment (–2.0 kg) than those who remained cognitively healthy (–1.2 kg), with a P value of .006.

A greater decline in weight per decade was associated with an increased risk for mild cognitive impairment (hazard ratio, 1.04; 95% confidence interval, 1.02 - 1.06; P < .001), after adjustment for many factors, including sex, education, and apolipoprotein E ε4 allele.

A weight loss of 5 kg per decade corresponded to a 24% increase in risk for mild cognitive impairment.

The authors note it was not possible to determine whether weight loss was intentional or unintentional.

Dr Roberts said several hypotheses may explain the results. "There is something known as anorexia of aging; as people get older they eat less. We believe there is something in the brain — maybe a hormone — that regulates feeding and affects people's desire to eat, which is altered with aging. This same process may also affect cognition in some way."

Another possibility is that this link may be related to smell. "As people age they lose their sense of smell, and this is associated with eating less," Dr Roberts explained. "Smell is related to taste and is an important part of eating. Loss of smell has also been associated with Alzheimer's disease and it is believed that regions in the brain that control smell may also be involved in early Alzheimer's disease."

She also suggested that weight loss could be used identify patients with mild cognitive impairment who are likely to go on to develop dementia.

"We know mild cognitive impairment is a strong risk factor for dementia but not everybody with mild cognitive impairment develops dementia. We are now looking at patents with mild cognitive impairment and whether those who lose the most weight are more likely to develop dementia. The data are being analyzed at present but preliminary results suggest this may be the case."

The study was supported by the National Institutes of Health, the Mayo Foundation for Medical Education and Research, the Robert H. and Clarice Smith and Abigail van Buren Alzheimer's Disease Research Program, the Clinical and Translational Science Award (which supports the Mayo Clinic Center for Clinical and Translational Science), and the National Center for Advancing Translational Sciences (a component of the National Institutes of Health) and was made possible by the Rochester Epidemiology Project. Dr Roberts receives funding from the National Institutes of Health. Disclosures for coauthors appear in the publication.

JAMA Neurol. Published online February 1, 2016. Abstract

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