Scyllo-inositol (ELND005) is an inositol isoform. Inositol is a derivative of cyclohexane with six hydroxyl groups, making it a polyol. It also is known as a sugar alcohol, having exactly the same molecular formula as glucose or other hexoses. Scyllo-inositol (ELND005) is a naturally occurring plant sugar alcohol found most abundantly in the coconut palm. It appears to accumulate in a number of human tissues and biofluids through dietary consumption. It has traditionally been considered to be a B vitamin although it has an uncertain status as a vitamin and a deficiency syndrome has not been identified in man. Although scyllo-inositol (ELND005) at pharmacologic doses may alter myo-inositol levels and indirectly affect phosphatidyl-inositol signaling, its main effects are thought to be binding and inhibition of beta-amyloid 42 peptide aggregation and formation of beta-amyloid fibrils. In transgenic animals, scyllo-inositol (ELND005) reduced brain beta-amyloid concentrations and plaque burden, preserved synaptic density, and improved learning deficits. Scyllo-inositol (ELND005) also appears to neutralize toxic effects of beta-amyloid oligomers, including amelioration of oligomer-induced synaptic loss, long-term potentiation inhibition, and memory deficits. Scyllo-inositol (ELND005) is an attractive candidate as a potential disease-modifying oral treatment for Alzheimer disease.