Bariatric surgery is associated with long-term improvements in cognition and brain structure in addition to general health benefits and expected weight loss, a large study found.
Among 133 adults with severe obesity who underwent bariatric surgery, roughly two in five showed > 20% improvement in global cognitive function at 24 months following the surgery.
“Notably, the temporal cortex exhibited not only higher cortical thickness but also higher vascular efficiency after surgery,” reported Amanda Kiliaan, PhD, Radboud University Medical Center, Nijmegen, the Netherlands, and colleagues.
“These results highlight beneficial vascular responses occurring in conjunction with bariatric surgery,” the researchers wrote.
They also suggested that weight-loss surgery may represent a treatment option for patients with obesity and dementia.
The study was published online on February 9, 2024, in JAMA Network Open.
Obesity is associated with an increased risk of developing dementia. Bariatric surgery-induced weight loss has been associated with improvements in brain function and structure in some small cohort studies with short follow-up periods. However, long-term neurological outcomes associated with bariatric surgery are unclear.
To investigate, Dr. Kiliaan and colleagues studied 133 adults with severe obesity (mean age, 46 years; 84% women) who underwent Roux-en-Y gastric bypass. The researchers collected relevant data from laboratory tests, cognitive tests, and MRI brain scans before surgery and at 6 and 24 months after surgery.
Overall, mean body weight, body mass index, waist circumference, and blood pressure were significantly lower at 6 and 24 months after surgery. At 24 months, significantly fewer patients were taking antihypertensive medication (17% vs 36% before surgery).
Improvements in inflammatory markers, depressive symptoms, and physical activity were also evident after surgery.
Cognitive Improvements
Several cognitive domains showed significant improvement at 6 and 24 months after bariatric surgery. Based on the 20% change index, improvements in working memory, episodic memory, and verbal fluency were seen in 11%, 32%, and 24% of participants, respectively.
Forty percent of patients showed improvement in their able to shift their attention, and 43% showed improvements in global cognition after surgery.
Several changes in brain parameters were also noted. Despite lower cerebral blood flow (CBF) in several regions, volumes of hippocampus, nucleus accumbens, frontal cortex, white matter, and white matter hyperintensity remained stable after surgery.
The temporal cortex showed a greater thickness (mean, 2.724 mm vs 2.761 mm; P = .007) and lower spatial coefficient of variation (sCOV; median, 4.41% vs 3.97%; P = .02) after surgery.
Overall, the results suggest that cognitive improvements “begin shortly after bariatric surgery and are long lasting,” the authors wrote.
Various factors may be involved including remission of comorbidities, higher physical activity, lower depressive symptoms, and lower inflammatory factors, they suggest. Stabilization of volume, CBF, and sCOV in brain regions, coupled with gains in cortical thickness and vascular efficiency in the temporal cortex could also play a role.
‘Remarkable’ Results
“Taken together, the research intimates bariatric surgery’s potential protective effects against dementia manifest through both weight-related brain changes and reducing cardiovascular risk factors,” Shaheen Lakhan, MD, a neurologist and researcher based in Miami, who wasn’t involved in the study, told this news organization.
“These remarkable neurological transformations intimate this surgery represents a pivotal opportunity to combat the parallel public health crises of obesity and dementia threatening society,” he said.
“In demonstrating a durable cognitive and brain boost out years beyond surgery, patients now have an emphatic answer — these aren’t short-lived benefits but rather profound improvements propelling them positively for the rest of life,” he added.
This opens up questions on whether the new class of obesity medications targeting glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide pathways, that can achieve weight loss approaching that of bariatric surgery, could have similar benefits.
The use of GLP-1 drugs have also shown neuroprotective effects such as improvement in motor and cognitive deficits, reduction of neuroinflammation, prevention of neuronal loss, and possibly slowing of neurodegeneration across animal models of Parkinson’s disease, Alzheimer’s disease, and stroke, said Dr. Lakhan. However, the exact mechanisms and ability to cross the blood-brain barrier require further confirmation, especially in humans.
Large, long-term, randomized controlled trials looking into potential effects of semaglutide on early Alzheimer›s disease, including the EVOKE Plus trial, are currently underway, he noted.
“These game-changing obesity drugs may hand us medicine’s holy grail — a pill to rival surgery’s brain benefits without the scalpel, allowing patients a more accessible path to protecting their brain,” Dr. Lakhan said.
The study had no funding from industry. Dr. Kiliaan and Dr. Lakhan had no relevant disclosures.
A version of this article first appeared on Medscape.com.