SAMA HOOLE: An aldehyde. Measured in the fluid around Alzheimer's brains at the University of Kentucky in 1997, at more than 3x the level in a healthy one.

Alzheimer's starts as a power cut, and the thing tripping the switch is seed oil going rancid inside your head.

4-hydroxynonenal. An aldehyde. Measured in the fluid around Alzheimer's brains at the University of Kentucky in 1997, at more than three times the level in a healthy… pic.twitter.com/Nm3FgZzn92

— Sama Hoole (@SamaHoole) August 21, 2026

Alzheimer's starts as a power cut, and the thing tripping the switch is seed oil going rancid inside your head. 4-hydroxynonenal. An aldehyde. Measured in the fluid around Alzheimer's brains at the University of Kentucky in 1997, at more than three times the level in a healthy one. It is also what comes off a chip pan, and for the same reason. It forms when omega-6 meets oxygen. Linoleic acid, and the arachidonic acid your body builds out of it. Linoleic acid is the fat that soybean, sunflower, rapeseed and corn oil are mostly made of, and a human being cannot manufacture a molecule of it. Every one in your brain came out of a bottle, a fryer or a packet. Your brain is two per cent of your body and burns twenty per cent of your energy. It stores no fuel. It is the fattiest organ you own and almost all of that fat is membrane, built from whatever you have been eating. Oxidation attacks double bonds. Linoleic acid has two. Beef fat and butter have almost none, and offer nothing to take hold of. Every nerve cell runs thousands of mitochondria, and mitochondria are where the oxygen is. So the aldehyde forms next to the engines, and an aldehyde is chemically sticky. It welds itself onto proteins and those proteins stop working. It jams the respiratory chain. It blocks the transporter the neuron uses to pull glucose in from outside. A cell that cannot burn glucose and cannot run its mitochondria leaks oxygen radicals instead. Those radicals attack more membrane fat. More membrane fat makes more aldehyde. The fire feeds itself, in the dark, for decades, in a tissue with no pain fibres in it. Which is why the scan that catches this earliest does not look for plaques. It measures glucose, and it finds the dim regions in people who are still driving to work. Plaques and tangles are the ash. Two thirds of the people with this disease are women, and it was women who were handed the guidance in 1983 and told to take the dripping out of the house and put the bottle in.

Thirty years and billions spent clearing the ash, and not a pound of it on the fuel.