We simultaneously performed structural MRI, ¹H magnetic resonance spectroscopy, and whole-body hydration status assessment to evaluate brain changes in patients with morbid obesity treated with intra-gastric balloon (IGB) for six months. We asked, if changes in myo-inositol ratios (marker of neuroinflammation) are related to brain volume increases accompanying IGB-induced weight loss.

Twenty five patients with morbid obesity (OB, 43.9 ± 11.8 years, BMI = 49.1 ± 7.2, 12 females, 9 without co-morbid conditions) were treated with IGB for six months. They underwent magnetic resonance imaging at 3T one month before IGB insertion, three months after insertion (N = 19), and one month after IGB removal (N = 14).

Insertion of IGB lead to 8.9% and 12.3% weight reduction over the first three months and over the entire treatment, respectively. Over the entire treatment, total gray matter volume increased by 2.0% (p = 0.009). These changes were mostly pronounced in the left precuneus and in the right frontal pole (>1.9%, p < 0.009). The increases in cortical volume in the right hemisphere and the left posterior cingulate cortical thickness over the entire treatment were significantly related to decreases in myo-inositol ratios measured over the first three months of the treatment (r < −0.740, p < 0.006).

IGB treatment lead to brain structural improvements consistent with earlier studies of bariatric patients without co-morbid conditions. Our results also pointed to improvements in brain regions, where atrophy in other studies was related to type 2 diabetes and hypertension. The correlations point to neuroinflammation as one of the potential processes behind brain volume reductions in patients with morbid obesity.