by Dr. Leo Galland
A study in the December 16, 2009 Journal of the American Medical Association (JAMA) found that higher levels of the hormone leptin protected people from developing Alzheimer’s disease1. The analysis came from the famed Framingham heart study, which has been following the residents of Framingham, Massachusetts, for decades.
When they grouped people according to their sex and level of leptin, they found that among the group with the lowest leptin levels, 25% developed Alzheimer’s disease during the study period, whereas only 6% of the highest leptin group developed Alzheimer’s disease. The protective effect of leptin was not found among people classified as obese, probably because being seriously overweight (body mass index greater than 30) is associated with resistance to the effects of leptin.
Protective effects of leptin against Alzheimer’s disease have been observed in other studies before, but this is the first to follow people for such a long period of time. Laboratory studies have demonstrated a direct protective effect of leptin in the brain, where it counteracts the biochemical changes that lead to Alzheimer’s disease.
Leptin is a hormone produced by fat cells. It’s best known for its effect in controlling body weight. Higher leptin levels suppress your appetite and speed up your metabolism, helping you to stay lean. People who are overweight become resistant to the effects of leptin, a condition called leptin resistance. One mechanism of leptin resistance is that leptin is not transported efficiently into the brain, where it needs to go to suppress appetite and to fight Alzheimer’s. People who are obese in mid-life actually have a greater risk of developing Alzheimer’s disease as they age. I believe that leptin resistance explains this association.
The existing scientific evidence, explained in detail in The Fat Resistance Diet, indicates that the leading cause of leptin resistance is inflammation. Overcoming leptin resistance is possible by following the principles of The Fat Resistance Diet to reverse inflammation. Studies have shown that people who eat abundantly of super foods have a reduced risk of Alzheimer’s disease2, an observation that completes the circle.
1. JAMA. 2009 Dec 16;302(23):2565-72.Association of plasma leptin levels with incident Alzheimer disease and MRI measures of brain aging. Lieb W, Beiser AS, Vasan RS, Tan ZS, Au R, Harris TB, Roubenoff R, Auerbach S, Decarli C, Wolf PA, Seshadri S.
2.Neurology. 2007 Nov 13;69(20):1921-30.Dietary patterns and risk of dementia: the Three-City cohort study. Barberger-Gateau P, Raffaitin C, Letenneur L, Berr C, Tzourio C, Dartigues JF, Alpérovitch A.