While the brain is not the focus of this essay, I cannot resist mentioning the importance of cholesterol to the brain and the evidence of mental impairment available from our data sets. Statins would be expected to have a negative impact on the brain, because, while the brain makes up only 2% of the body's weight, it houses 25% of the body's cholesterol. Cholesterol is highly concentrated in the myelin sheath, which encloses axons which transport messages long distances (Saher et al., 2005). Cholesterol also plays a crucial role in the transmission of neurotransmitters across the synapse (Tong et al, 2009). We found highly skewed distribution of word frequencies for dementia, Parkinson's disease, and short term memory loss, with all of these occurring much more frequently in the statin reviews than in the comparison reviews.
A recent evidence-based article (Cable, 2009) found that statin drug users had a high incidence of neurological disorders, especially neuropathy, parasthesia and neuralgia, and appeared to be at higher risk to the debilitating neurological diseases, ALS and Parkinson's disease. The evidence was based on careful manual labeling of a set of self-reported accounts from 351 patients. A mechanism for such damage could involve interference with the ability of oligodendrocytes, specialized glial cells in the nervous system, to supply sufficient cholesterol to the myelin sheath surrounding nerve axons. Genetically-engineered mice with defective oligodendrocytes exhibit visible pathologies in the myelin sheath which manifest as muscle twitches and tremors (Saher et al, 2005). Cognitive impairment, memory loss, mental confusion, and depression were also significantly present in Cable’s patient population. Thus, his analysis of 351 adverse drug reports was largely consistent with our analysis of 8400 reports.