Body–Brain Connections: The Effects of Obesity and Behavioral Interventions on Neurocognitive Aging

Abstract

Obesity is a growing public health problem in the United States, particularly in middle-aged and older adults. Although the key factors leading to a population increase in body weight are still under investigation, there is evidence that certain behavioral interventions can mitigate the negative cognitive and brain (“neurocognitive”) health consequences of obesity. The two primary behaviors most often targeted for weight loss are caloric intake and physical activity. These behaviors might have independent, as well as overlapping/synergistic effects on neurocognitive health. To date obesity is often described independently from behavioral interventions in regards to neurocognitive outcomes, yet there is conceptual and mechanistic overlap between these constructs. This review summarizes evidence linking obesity and modifiable behaviors, such as physical activity and diet, with brain morphology (e.g., gray and white matter volume and integrity), brain function (e.g., functional activation and connectivity), and cognitive function across the adult lifespan. In particular, we review evidence bearing on the following question: Are associations between obesity and brain health in aging adults modifiable by behavioral interventions?

Hallmarks of Brain Aging: Adaptive and Pathological Modification by Metabolic States

“…Individuals who are sedentary and overindulgent are also prone to impaired brain function and neurodegenerative disorders as they age. On average, the cognitive performance of individuals who are metabolically morbid is poorer than their age-matched healthy counterparts (Kullmann et al, 2016; Stillman et al, 2017). Brain imaging studies have documented reduced gray matter volumes and white matter integrity in multiple brain regions, and reduced functional connectivity between brain regions in obese individuals, particularly those with abdominal obesity and insulin resistance (Debette et al, 2014; Janowitz et al, 2015; Kullmann et al, 2015).…”

Increasing body mass index in an elderly cohort: Effects on the quantitative MR parameters of the brain

“…6 The influence of obesity on neurocognitive aging has become the focus of attention for various researchers (for a review, see Ref. 7). Although there are numerous studies reporting altered brain structure due to obesity, most of them have concentrated either on the volumetric changes of the brain or differences in the diffusion tensor imaging indices.…”

Zebrafish Aging Models and Possible Interventions

“…Dietary restriction has been shown to have beneficial effects on both cognitive aging and the associated neurobiological changes in the aging brain. This has been shown in humans [76] and animal models [77][78][79][80]. Our research group proposed utilizing a dietary manipulation such as caloric restriction (CR) to alter the aging process in zebrafish.…”

“…Contrary to CR and IF paradigms that decelerate the aging process, overfeeding has been proposed to accelerate aging. For example, the effects of obesity on behavioral and neurobiological changes have been investigated in humans [76] and animal models [97]. Zebrafish, like humans, will overeat if exposed to large amounts of food [98].…”