A popular dietary supplement and a curry spice may affect Alzheimer's disease–related chemical processes in the brain, according to a study reported in The Journal of Neuroscience. Alzheimer's disease is the most common form of dementia in older people. This study, which used an animal (mouse) model of Alzheimer's disease, builds on previous research linking the disease to peptides (amino acid chains) called β‑amyloids and to defective insulin-processing by the brain. A particular β‑amyloid, Aβ‑42, is associated with Alzheimer's disease. There is also epidemiological evidence—type II diabetes appears to increase the risk of Alzheimer's disease—to suggest a connection between insulin resistance and the disease. Funded in part by NCCAM, the current study looked at two dietary supplements: fish oil rich in the omega‑3 fatty acid docosahexaenoic acid (DHA); and curcumin, a component of turmeric. Researchers fed the Alzheimer's disease–model mice a regular or fatty diet; some of the mice also received fish oil and/or curcumin. They found that the high-fat diet increased Alzheimer's disease–related chemical processes in the brain, and that fish oil and curcumin, alone or in combination, counteracted this effect. DHA and curcumin also protected cognitive performance for mice on the high-fat diet—i.e., how well the mice remembered a maze. The researchers also explored the chemical pathways involved in the effects they observed, examining tissues from the Alzheimer's disease mice, neural cell cultures from fetal rats, and autopsied brain cells from people who had Alzheimer's disease. Identifying these pathways is a critical step in understanding the disease and developing potential therapies.
Ma QL, Yang F, Rosario ER, et al.. β‑amyloid oligomers induce phosphorylation of tau and inactivation of insulin receptor substrate via c‑Jun N‑terminal kinase signaling: suppression by omega‑3 fatty acids and curcumin.. Journal of Neuroscience.;29(28):9078–9089..2009