Structural Brain Changes Associated with Overweight and Obesity

Abstract

Obesity is a global health problem with a broad set of comorbidities, such as malnutrition, metabolic syndrome, diabetes, systemic hypertension, heart failure, and kidney failure. This review describes recent findings of neuroimaging and two studies of cell density regarding the roles of overnutrition-induced hypothalamic inflammation in neurodegeneration. These studies provided consistent evidence of smaller cortical thickness or reduction in the gray matter volume in people with overweight and obesity; however, the investigated brain regions varied across the studies. In general, bilateral frontal and temporal areas, basal nuclei, and cerebellum are more commonly involved. Mechanisms of volume reduction are unknown, and neuroinflammation caused by obesity is likely to induce neuronal loss. Adipocytes, macrophages of the adipose tissue, and gut dysbiosis in overweight and obese individuals result in the secretion of the cytokines and chemokines that cross the blood-brain barrier and may stimulate microglia, which in turn also release proinflammatory cytokines. This leads to chronic low-grade neuroinflammation and may be an important factor for apoptotic signaling and neuronal death. Additionally, significant microangiopathy observed in rat models may be another important mechanism of induction of apoptosis. Neuroinflammation in neurodegenerative diseases (such as Alzheimer’s and Parkinson’s diseases) may be similar to that in metabolic diseases induced by malnutrition. Poor cognitive performance, mainly in executive functions, in individuals with obesity is also discussed. This review highlights the neuroinflammatory and neurodegenerative mechanisms linked to obesity and emphasizes the importance of developing effective prevention and treatment intervention strategies for overweight and obese individuals.

Functional Magnetic Resonance Imaging and Obesity—Novel Ways to Seen the Unseen

“…Such substances may cross the blood–brain barrier and induce local inflammation of the nervous tissue. Obesity-induced neuroinflammation may lead to neuronal and synaptic loss resulting in progressive cognitive decline and also to the disruption of hypothalamic satiety signals and promotion of overeating [ 18 , 26 ]. In addition, using magnetic resonance, obese individuals were shown to exhibit increased hypothalamic gliosis in response to ongoing inflammation that may contribute to hypothalamic leptin resistance [ 27 ].…”

“…In recent years, studies utilizing fMRI have gained popularity as a way to understand the mechanisms of the development of eating disorders and obesity on the neural level, which represents a breakthrough in how obese people are considered to have altered brain signaling [ 18 , 30 ]. Brain activity in cortical neuronal networks involved in homeostatic control and hedonic responses is generally altered in obese individuals.…”

“…It is believed that higher BMI might be associated with greater hypothalamic connectivity within the regions involved in food motivation and reduced connectivity with the structures associated with cognitive control of food intake. The detailed differences have been described further in the manuscripts [ 17 , 18 ].…”

Obesity and the Brain

“…They also can induce microglia, which release proinflammatory cytokines. Consequently, it can lead to chronic low-grade neuroinflammation and may be a key factor for apoptotic signaling and neuronal death [ 26 ]. Furthermore, this work mentions a poor cognitive performance, mainly in executive functions, in individuals with obesity.…”

The Emerging Role of Metabolism in Brain-Heart Axis: New Challenge for the Therapy and Prevention of Alzheimer Disease. May Thioredoxin Interacting Protein (TXNIP) Play a Role?

“…In particular, cardiovascular diseases (CVDs) are associated to cognitive decline and participate to AD [ 7 ]. In addition, the risk factors for CVDs promote also AD: hypertension [ 8 ], diabetes [ 9 ], obesity [ 10 ], dyslipidemia [ 11 ]. In agreement, Asymmentric DiMethyl Arginine (ADMA) plasma levels, which is an excellent biomarker for sporadic small vessels disease (SVD) and indicates early endothelial dysfunction [ 12 ], is also a blood biomarker for AD [ 13 ] and its levels correlate with cognitive decline [ 14 ].…”