 The incidence rate was 200 per 100,000 per year and it was 100 times more prevalent than in the rest of the world.Neurologist Oliver Sacks detailed this disease in his book "The Island of the Colorblind".Sacks and Paul Alan Cox subsequently wrote that the Guam flying fox, a bat extinct due to overhunting, had been feeding on Federico nuts ("Cycas micronesica") and concentrating β-methylamino-L-alanine (BMAA), a known neurotoxin, in its body fat.