High caloric intake improves neuronal metabolism and functional hyperemia in a rat model of early AD pathology.

While obesity has been linked to both increased and decreased rate of cognitive decline in Alzheimer's Disease (AD) patients, there is no consensus on the interaction between obesity and AD. The TgF344-AD rat model was used to investigate the effects of high carbohydrate, high fat (HCHF) diet on brain glucose metabolism and hemodynamics in the presence or absence of AD transgenes, in presymptomatic (6-month-old) vs. symptomatic (12-month-old) stages of AD progression using non-invasive neuroimaging. In presymptomatic AD, HCHF exerted detrimental effects, attenuating both hippocampal glucose uptake and resting perfusion in both non-transgenic and TgAD cohorts, when compared to CHOW-fed cohorts. In contrast, HCHF consumption was beneficial in established AD, resolving the AD-progression associated attenuation in hippocampal glucose uptake and functional hyperemia. Whereas HCHF was harmful to the presymptomatic AD brain, it ameliorated deficits in hippocampal metabolism and neurovascular coupling in symptomatic TgAD rats.