Love to binge on cheeseburgers and fries? Beware, just four days of these fatty foods can rewire the brain's memory hub -- leading to risk of cognitive dysfunction, according to a study. The research led by the University of North Carolina (UNC) in the US suggests that fatty junk foods can affect the brain almost immediately, well before the onset of weight gain or diabetes.
The results open the door to early interventions that can prevent even long-term memory loss associated with obesity, which is mainly driven by Western-style junk food rich in saturated fat. The findings, published in the journal Neuron, showed that a special group of brain cells in the hippocampus -- called CCK interneurons -- become overly active after eating a high-fat diet (HFD), due to an impaired ability of the brain to receive glucose (sugar).
This overactivity disrupts how the hippocampus processes memory, even after just a few days of a high-fat diet, said Juan Song, Principal Investigator and professor of pharmacology at UNC School of Medicine. The discovery also showed that a protein called PKM2, which controls how brain cells use energy, plays a key role in this problem.
"We knew that diet and metabolism could affect brain health, but we didn't expect to find such a specific and vulnerable group of brain cells, CCK interneurons in the hippocampus, that were directly disrupted by short-term high-fat diet exposure," Song said, who is a member of the UNC Neuroscience Center.
"What surprised us most was how quickly these cells changed their activity in response to reduced glucose availability, and how this shift alone was enough to impair memory," added Song. For the study, the team placed mouse models on a high-fat diet resembling fatty junk food before starting behavioural testing.
Within four days of eating a high-fat diet, results showed CCK interneurons in the brain's memory hub became abnormally active. The research also shows that restoring brain glucose levels actually calmed down overactive neurons and fixed memory problems in mice.
The study found interventions like dietary modifications or pharmacological approaches may be effective in preserving brain health for obesity-related neurodegeneration. Notably, researchers discovered that dietary interventions like intermittent fasting periods following a high-fat diet were sufficient to normalise CCK interneurons and improve memory function.