A recent study indicates that obesity places additional stress on the brain and influences key markers of cognitive health.
A recent research collaboration led by Annalena Venneri of the University of Sheffield (UK) has uncovered a link between obesity and brain health. The findings of the multimodal neuroimaging study could have implications for the management and prevention of conditions such as Alzheimer’s.
Signs of neurodegenerative diseases tend to exist for a long time before they become symptomatic, often going undetected as the diseases slowly progress. As a result, there is a large focus on the prevention and management of these early stages of the disease with numerous research teams studying the factors that may impact the development of each disease.
To study the potential impact of obesity on brain health during different stages of Alzheimer’s, the researchers studied MRI scans from 47 patients diagnosed with mild Alzheimer’s disease dementia, 68 patients with cognitive impairment and 57 cognitively healthy individuals. In each of these images, the team assessed the grey matter volume (GMV), white matter integrity (WMI) and cerebral blood flow (CBF).
Grey matter represents the neuronal cell bodies, dendrites, unmyelinated axons, glial cells, synapses and capillaries and a decrease in GMV is well established to correlate with declining cognitive function as we age. The integrity of white matter, which represents the myelinated nerve fibers that transport information throughout our brain, is vital for efficient cognitive function. CBF is another key indicator of a healthy brain and changes in CBF have been shown to regulate the activity of individual neurons.
Three computational techniques, voxel-based morphometry, fractional anisotropy and pCASL sequences were used to analyze GMC, WMI and CBF respectively, creating maps for each measurement. Voxel-wise associations were then run between each of these maps and measurements of visceral obesity.
This approach found a correlation between obesity and poor WMI and CBF in the temporoparietal region of the brains of cognitively healthy individuals. These negative correlations were also observed in those with mild cognitive impairment in the frontal, temporal and brainstem regions of their brains.
A common indicator of Alzheimer’s and dementia is weight loss, as those living with the condition forget to feed themselves appropriately. In the mild Alzheimer’s patients a positive correlation was observed between increased BMI – still within the normal range – and GMV. This suggests a potential protective effect of a higher body fat percentage, within a healthy range, during more advanced Alzheimer’s. This may be due to the availability of the nutritional resources required to protect against neural damage.
Discussing the importance of the study, Venneri stated that, “prevention plays such an important role in the fight against the disease. It is important to stress this study does not show that obesity causes Alzheimer’s, but what it does show is that being overweight is an additional burden on brain health and it may exacerbate the disease.”
While co-author Hilkka Soininen highlighted the uncovered importance of maintaining a healthy weight when managing Alzheimer’s: “it’s important to avoid obesity for brain health, but for patients with Alzheimer’s disease, it is essential to take care of proper nutrition and maintain a healthy weight.”
