Childhood obesity is growing into epidemic levels in the United States, with current estimates of over 15 million youth, including >20% of adolescents affected by obesity [1].
The increase in obesity is also associated with profound physical, mental and cognitive health problems, including cardiovascular disease, disordered sleep,
diabetes, suicide ideation, impaired attention, social skills, executive function, visuospatial processing, and verbal skills [2].
A staggering 60% of children ages 2-19 years are estimated to have obesity when they become adults [3].
In addition to the profound effects on the individual, there are enormous socioeconomic costs associated with obesity. As the rate continues to grow, there will need to be a call for urgent action to understand the underlying causes and develop individualized approaches to mitigate it.
The first two decades of life are crucial for maintaining health body mass index (BMI) levels. The effects of high BMI levels on the developing brain, and associated mental and cognitive health problems are not completely elucidated [4].
Reports of negative relationships between BMI and cognitive function have been reported as early as preschool ages [2].
Research has linked high BMI to decreased cortical thickness of regions involved in executive function, increased inflammation in reward structures and changes in total brain volume [5].
There has not been any research that particularly investigated the effects of excess BMI on topological organization
(how neurological connections are arranged and organized in the brain) of maturating functional networks in early adolescence, and the associated changes in
brain structures and their cognitive connections.
In order to address this gap in knowledge, a recent study investigated the relationship between excess BMI and the topological organization of large-scale resting-state functional brain networks that perform a fundamental role in cognitive function in early adolescence.
Not surprisingly, youth with overweight or obesity were less physically active, obtained less than the recommended sleep for their age, snored more frequently, and spent more time using an electronic device.
In addition, more
participants with excess BMI had lower-self esteem tied to weight, in agreement with prior research on BMI-related image and self-worth issues [6].
A very significant finding from this research is that across scales of spatial organization in the brain, youth with obesity and overweight had similar alterations in topological network properties
(how neurological connections are arranged and organized in the brain), compared to those with normal BMI.
These alterations included lower network efficiency, impacting how quickly information is processed through the brain, lower global and local clustering, and connectedness, which alters the brain’s ability to perform computations in functionally specialized regions, and lower topological robustness, which translates to being more vulnerable to the negative effects of stress.
The implications of the identified effects on the entire developing neural connections in the brain suggest that excess BMI may have global effects on the developing brain.
It seems that lower brain-wide efficiency of information processing and communication between brain regions, and impaired ability to perform domain-specific computations may have ubiquitous adverse effects across cognitive domains and processes. This increase in topological vulnerability in the developing brain can lead to both cognitive deficits and mental health issues across the lifespan.
Although there were numerous strengths of this research, there are some limitations such as not having any information available on nutrition, genetics, and family history of excess BMI ant baseline assessment. This data could have provided valuable insights into causal factors impacting BMI in addition to developing brain circuits.
This research added valuable insight into the understanding of the effects of excess BMI on the brain’s developing circuits. One important caveat I want to point out is that a high BMI is not automatically considered bad.
It depends on body composition and BMI does not take that into consideration.
There are individuals with highly developed muscles who have very high BMI levels. These individuals are extremely fit and healthy and would not fall into the category that was included in the data set of this study. This study included individuals that were overweight and obese and therefore, had high levels of adipose tissue which caused the high levels of BMI.
BMI is calculated by taking someone’s height and weight and does not factor in body composition (lean and fat tissue) of the individual.
The primary finding, which also has significant clinical implications, is that not only obesity, but also overweight may have similar widespread detrimental effects on developing neural circuits, the development of their underlying brain structures, and the cognitive processes they support.
Alterations occurring in the brain circuitry due to excess BMI may disrupt normal neural maturation and potentially have serious negative implications for
long-term cognitive health.
Importantly, these findings are based on a large sample that captures the heterogeneity of typical brain development and provide strong evidence of detrimental effects of unhealthy excess BMI on brain development. This knowledge can be leveraged in a positive way to raise social awareness and implement critical new policies to fight the childhood weight epidemic in the United States and other developed countries.
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References:
1. Prevention., C.f.D.C.a.; Available from: https://www.cdc.gov/.
2. Brooks, S.J., C. Smith, and C. Stamoulis, Excess BMI in early adolescence adversely impacts maturating functional circuits supporting high-level cognition and their structural correlates. Int J Obes (Lond), 2023.
3. Ward, Z.J., et al., Simulation of Growth Trajectories of Childhood Obesity into Adulthood. N Engl J Med, 2017. 377(22): p. 2145-2153.
4. Griffiths, L.J., T.J. Parsons, and A.J. Hill, Self-esteem and quality of life in obese children and adolescents: a systematic review. Int J Pediatr Obes, 2010. 5(4): p. 282-304.
5. Ronan, L., A. Alexander-Bloch, and P.C. Fletcher, Childhood Obesity, Cortical Structure, and Executive Function in Healthy Children. Cereb Cortex, 2020. 30(4): p. 2519-2528.
6. Harriger, J.A. and J.K. Thompson, Psychological consequences of obesity: weight bias and body image in overweight and obese youth. Int Rev Psychiatry, 2012. 24(3): p. 247-53.
