Research regarding Parkinson’s Disease has long been controversial due to many unconventional methods being utilised in the hope of finding a cure and understanding its development. However, we were recently made aware of a study that looked at the use of statins and the development of Parkinson’s Disease that truly intrigued us.

The study, which was published in Neurology, included a total of 43 810 individuals in Taiwan who did not have Parkinson’s Disease (PD) but were treated with statins. As the national health insurance in Taiwan requires that patients do not get statins once the patients’ cholesterol levels are in line with the treatment goal, the researchers were able to consider potential effects of discontinuing statins, such as the risk of PD. The key findings indicated that patients who continued to take fat-soluble statins had a decreased risk of developing PD in contrast to patients who had ceased taking statins, or were taking water-soluble statins. Individuals in the group who ceased administering fat-soluble statins appeared to have a 58% greater likelihood of developing PD than those who stayed on the fat-soluble statins. This effect remained after the researchers had taken several other co-morbidities into account.

For those interested in the development of PD, the study certainly makes for interesting reading when read in conjunction with the academic discussions it has prompted with regards to the potential underlying mechanisms that could have played a role in the findings.

The value from the study comes in several forms. From the fact that they used a substantial national sample to the distinguishing of fat-soluble and water-soluble statins, it is easy to see why so many discussions have followed.

As with any research, there are areas that could have been done better. For instance, there is missing information with regards to the level of cholesterol the participants had, as well as a lack of differentiation of caffeine and nicotine intake. Consequently, it cannot be disentangled whether the fat-soluble statins had a neuro-protective effect or whether there was an indirect effect from changes in cholesterol.

This study is very interesting and confirms results in an earlier study on mice. Here is the earlier study that was published a few years ago.

The use of statins in diseases of the CNS (central nervous system) appears to be focus of recent research. For instance, several studies have considered whether the area of use of statins could be expanded to Alzheimer's, stroke and MS.

Another area of interest has been open angle glaucoma (OAG), which is a condition of the eye that comprises optic neuropathy of a chronic and progressive nature, usually in the presence of intraocular pressure above that which is normal. Statins are thought to work provide a level of protection by reducing the blood cholesterol levels, which in turn reduces the pressure within the blood vessels in the eye. Given that non-statin cholesterol lowering medications did not appear to have such a pronounced effect on open angle glaucoma diagnoses, it is probable that statins convey a protective property beyond their cholesterol lowering impact but this has not been demonstrated.

This month, the journal Ophthamology published a study where 524 109 US patients’ medical and pharmaceutical records were compared over a period of seven years to see if individuals who were prescribed statins to be used for hyperlipidaemia had a reduced risk of developing OEG.

The key findings indicated that individuals who had no prior diagnosis of OAG had a decreased risk of 8% of developing it and that individuals who had a glaucoma suspect diagnosis had a decreased risk of developing OAG of 9%. The findings also suggested that these individuals were at a decreased risk of receiving more than one prescription for intraocular pressure. Perhaps, the most interesting finding was that the researchers demonstrated a dose-response effect, whereby the longer individuals had been prescribed statins the greater the protection appeared to be.

This study benefitted from a large sample and from following up patients over a relatively long period of time. However, the use of medical records could be seen as both a strength and a weakness of the study. Although it minimised the possibility of incomplete verbal information from participants, there was also no possibility to know whether they had consumed all the medication they were prescribed. Overall, it is also important to consider that because the researchers used medical records, the sample only represented insured individuals, which limits the generalizability of the findings. The full details of the study can be read here.

This is an interesting study and it augments the body of evidence that suggests that statins may have beneficial properties beyond being a treatment for hypercholesterolemia.