Decreased brain entropy in the left pallidum is associated with memory impairment in obese individuals: Evidence from resting-state fMRI

Obesity significantly increases not only the incidence and mortality rates of cardiovascular diseases, diabetes, and other metabolic disorders, but also elevates the risk of cognitive impairment-related conditions such as Alzheimer's disease by 3 to 5 times. Based on some brain regions related to reward drive, this study combined brain entropy (BEN) and resting state functional connectivity (RSFC) to explore the neural basis of obesity-induced memory impairment.

Based on resting-state functional magnetic resonance imaging (rs-fMRI) data from 23 obese individuals and 36 healthy controls, the BEN values of some brain regions related to reward drive (Nucleus accumbens, Pallidum, Caudate, and Anterior cingulate cortex) were calculated. Mediation analysis was performed to examine whether body mass index (BMI) mediates the relationship between BEN and memory quotient (MQ). Additionally, whole-brain functional connectivity analysis was conducted based on regions showing significant BEN differences.

The BEN in left pallidum (lPAL) was significantly reduced in the obese group compared to controls (p = 0.005). Moreover, BMI mediated the relationship between lPAL entropy and MQ (Indirect effect: 0.2227, 95 % CI [0.0866, 0.3658]). Functional connectivity analysis revealed decreased connectivity between the lPAL and the right superior parietal gyrus, cerebellar Crus II, and cerebellar VIIB in the obese group, along with increased connectivity between the lPAL and the right pallidum.

BMI fully mediates the reduced brain complexity of the left pallidum in obese individuals, which is associated with memory impairment and is accompanied by changes in specific functional connectivity patterns. These findings provide new insights into the neural substrates of obesity-related cognitive decline.