Nutritionist calculating body mass index of woman for obesity treatment in a clinic room.
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The cognitive benefits from bariatric surgery (BS) continue to accrue after initial weight loss, according to new research from a European team. Bariatric surgery was associated with long-term health benefits, including improvements in comorbidities, inflammation, and cognition. Moreover, higher cortical thickness and lower spatial coefficient of variation were found in the temporal lobe two years after surgery.

This work appears in JAMA Network (Feb. 9, 2024). The lead author is Amanda J. Kilaan, PhD, of the Radboud University Medical Center, Donders Institute for Brain, Cognition, and Behavior in the Netherlands.

The authors note, “Obesity is inversely associated with gray matter (GM) volume and white matter (WM) integrity and positively associated with WM hyperintensities (WMH). These brain changes might be induced by reduced cerebral blood flow, which often coincides with obesity. Cognitive functions, particularly domains of executive function, attention,and episodic and working memory, are associated with obesity, corresponding to changes in hippocampus and prefrontal regions.”

There is evidence that long term weight loss can reduce potential consequences of obesity on the brain. And there’s evidence that BS leads to improved cognition and changed brain structure. However, previous studies of this association have used small cohorts and short follow-up periods, making it difficult to determine long-term neurological outcomes associated with weight loss surgery.

This study aimed to determine long-term associations of weight loss after BS with cognition and brain structure and perfusion. It included 133 adults with severe obesity who underwent bariatric surgery, cognitive function, inflammatory biomarkers, comorbidities, physical activity, and depressive symptoms were still improved two years after bariatric surgery. 

This cohort study included participants from the Bariatric Surgery Rijnstate and Radboudumc Neuroimaging and Cognition in Obesity study. Data from participants with severe obesity (body mass index [BMI; calculated as weight in kilograms divided by height in meters squared] >40, or BMI >35 with comorbidities) eligible for Roux-en-Y gastric bypass and aged 35 to 55 years were enrolled from a hospital specialized in BS (Rijnstate Hospital, Arnhem, the Netherlands). Participants were recruited between September 2018 and December 2020 with follow-up till March 2023. Data were collected before BS and at six and 24 months after BS. Data were analyzed from March to November 2023.

Among these total 133 participants, global cognition was at least 20% higher in 52 participants (42.9%) at 24 months after BS. Compared with baseline, at 24 months, inflammatory markers were lower, fewer patients used antihypertensives, and patients had lower depressive symptoms and greater physical activity. 

After weight loss surgery, brain structure and perfusion were lower in most brain regions, while hippocampal and white matter volume remained stable. Cerebral blood flow and spatial coefficient of variation (sCOV) did not change in nucleus accumbens and parietal cortex. On neuroimaging, the temporal lobe showed changes in structure and function.

These findings suggest bariatric surgery is associated with health benefits at least two years after surgery. Patients who had bariatric surgery showed improved cognition and general health and changed blood vessel efficiency and cortical thickness of the temporal cortex. 

The authors say these findings may improve treatment options for patients with obesity and dementia.

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