Continuing weight loss from midlife predicts MCI risk

By Lucy Piper, Senior medwireNews Reporter

Increasing weight loss from middle age through the later stages of life may be an indicator of mild cognitive impairment (MCI), suggest study findings.

“While weight loss may not be causally related to MCI, we hypothesize that weight loss may represent a prodromal stage or an early manifestation of MCI”, say researcher Rosebud Roberts (Mayo Clinic, Rochester, Minnesota, USA) and colleagues.

“Consistent with this, there was no interaction of weight loss with midlife weight; even among persons who were of normal weight in midlife, a greater weight loss was associated with an increased risk of MCI later in life.”

The team found an average weight loss per decade from midlife (40 to 65 years of age) of 2.0 kg among 524 individuals aged 70 years or older who had developed MCI over an average follow-up of 4.4 years. This was significantly greater than the 1.2 kg seen in 1371 similarly aged individuals who remained cognitively healthy.

After taking into account gender, education and apolipoprotein Eε4 status, a greater decline in weight per decade was associated with a significant 1.04-fold increased risk of incident MCI. And Roberts and team estimate that a weight loss of 5 kg per decade would correspond to a 24% increased risk of MCI.

Consistent with the findings, a greater decrease in body mass index per decade was associated with an increased risk of MCI, although to a lesser degree.

The researchers note in JAMA Neurology that weight loss “is the key weight-related marker of incident MCI in the elderly”; both a higher maximum midlife weight and lower weight in later life were also associated with incident MCI, but the association was stronger with weight loss per decade.

They suggest that dysfunctional production of hormones associated with dietary intake and energy metabolism or the effect of neuropsychiatric symptoms accompanying MCI and dementia, such as apathy and depression, on an individual’s appetite are possible causal explanations for the association.

Alternatively, it could be the result of shared aetiologies, they say, such as olfactory dysfunction associated with cognitive impairment affecting an individual’s smell and taste and decreasing their appetite.

“[O]ur findings suggest that an increasing rate of weight loss from midlife to late life is a marker for MCI and may help identify persons at increased risk of MCI”, the researchers conclude.

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