People who are severely overweight are less likely to be able to re-wire their brains and find new neural pathways, a discovery that has significant implications for people recovering from a stroke or brain injury. In the paper, ‘Obesity is Associated with Reduced Plasticity of the Human Motor Cortex’, published in Brain Sciences, researchers from UniSA and Deakin University report0 that brain plasticity is impaired in people with obesity, making it less likely that they can learn new tasks or remember things.
Using a series of experiments involving transcranial magnetic stimulation, the researchers tested 15 people with obesity aged between 18 and 60, and compared them with 15 people in a healthy-weight control group.
A brain stimulation protocol known as continuous theta burst transcranial magnetic stimulation was applied to the motor cortex to induce a brief suppression of cortical excitability. The suppression of cortical excitability was quantified using single-pulse transcranial magnetic stimulation to record and measure the amplitude of the motor evoked potential in a peripheral hand muscle.
The results demonstrate that the healthy-weight group had a significant suppression of cortical excitability following continuous theta burst stimulation (cTBS), but there was no change in excitability for the obese group. Comparing the response to cTBS between groups demonstrated that there was an impaired plasticity response for the obese group when compared to the healthy-weight group.
The researchers suggested that this might suggest that the capacity for plasticity is reduced in people who are obese. Given the importance of plasticity for human behaviour, the results add further emphasis to the potentially detrimental health effects of obesity.
UniSA researcher, Dr Brenton Hordacre explained that the findings provide the first physiological evidence of a link between obesity and reduced brain plasticity.
"Obesity is already associated with a raft of adverse health effects, including a higher risk of cardiovascular disease, metabolic disorders and dementia. For the first time, we found that obesity was associated with impaired brain function, adding further support for the need to address the obesity epidemic. A growing number of people are obese—650 million according to the World Health Organization - which not only has health consequences but is a serious financial burden for global health systems. These new findings suggest that losing weight is particularly important for healthy brain aging or for recovery in people who suffer strokes or brain injuries, where learning is fundamental for recovery."