News & Comment

We have greater knowledge about the genetic contributions to Parkinson’s disease (PD) with major gene discoveries occurring in the last few decades and the identification of risk alleles revealed by genome-wide association studies (GWAS). This has led to increased genetic testing fueled by both patient and consumer interest and emerging clinical trials targeting genetic forms of the disease. Attention has turned to prodromal forms of neurodegenerative diseases, including PD, resulting in assessments of individuals at risk, with genetic testing often included in the evaluation. These trends suggest that neurologists, clinical geneticists, genetic counselors, and other clinicians across primary care and various specialties should be prepared to answer questions about PD genetic risks and test results. The aim of this article is to provide genetic information for professionals to use in their communication to patients and families who have experienced PD. This includes up-to-date information on PD genes, variants, inheritance patterns, and chances of disease to be used for risk counseling, as well as insurance considerations and ethical issues.

The prevalence of smell loss in Parkinson’s Disease (PD) patients greatly exceeds that of the characteristic motor symptoms defining the disease by several years. One hypothesis of the cause of PD states that it is initiated in the olfactory bulb — the critical first central processing stage of the olfactory system — and that the olfactory nerve might serve as an entry point to the OB for pathogens or environmental components. But what if there was no OB to start with? Recent data demonstrate that cortical, but not peripheral, blindness acts as a protective factor against schizophrenia and other psychotic disorders. We hypothesize that individuals with the rare diagnose Isolated Congential Anosmia (ICA) are immune to PD given that they are born without OBs. If true, it would strongly support the theory that PD might start in the bulb. However, if one could identify even one single PD patient with an established ICA diagnosis with non-existing OBs, a so-called black swan, this would effectively falsify the hypothesis. In this commentary, we model the likely occurrence of such potential comorbidity and we postulate that it is possible to find this black swan; a finding that would falsify a salient hypothesis within the PD research community.

Parkinson’s disease (PD) is a neurodegenerative condition, characterized by motor, non-motor disability, and a reduced quality of life. Stimulated by a question raised by a person with PD, we posted an orienting survey on social media, asking whether there is possibly any “silver lining” (an upside) to having PD. Most respondents identified one or more positive changes, mainly a new focus in life, better coping skills, new activities, healthier lifestyle, and improved relationships with relatives and friends. This ability to perceive a silver lining of disease is in line with the concept of adversarial growth in illness, and positive health, which underscores resilience, self-management, and the ability to adapt. Importantly, not every respondent identified an upside to living with PD, so this is very much an example of personalized medicine. This is a delicate, difficult issue, and discussing the presence of silver linings may feel counterintuitive. However, exploring this issue may help people with PD and caregivers to better deal with the disease, and allow medical professionals to provide better support, to learn about coping strategies, to understand the degree of disease acceptance, and to enhance a healthier lifestyle. Further research should demonstrate whether addressing silver linings may impact positively on the outcome of PD and on the perceived quality of life. To facilitate this process, we have adapted a pre-existing silver lining questionnaire (SLQ-38) in light of the responses provided by people with PD, to offer a simple, feasible tool to further explore this issue in clinical and research settings.