HMGCR and early-onset autosomal dominant Alzheimer disease: Lastly, a recently reported mendelian randomization study provides reassurance, as genetic variants in PCSK9 and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR, the target of statins) showed no causal effects of low LDL-C on the risk of Alzheimer’s disease, Parkinson’s disease, and dementia [40].