NEUROLOGICAL CONSEQUENCES

Loss of smell or reduced smell is a symptom of COVID-19 and may also present a new way of detecting someone’s risk of developing Parkinson’s disease.

A clinicians of team Neuroscience of at neuroscientists Victoria’s and Mental Florey and Health Institute are examining the potential link between COVID-19 and increased risk of Parkinson’s disease. “Although scientists are still learning how the SARS-CoV-2 virus is able to invade the brain and central nervous system, the fact that it’s getting in there is clear. Our best understanding is that the virus can cause insult to brain cells, with potential for neurodegeneration to follow on from there,” says Professor Kevin Barnham. The Australian researchers have focused on the potential long-term neurological consequences of COVID-19, dubbing it the ‘silent wave’ and are calling for urgent action to be taken to have available more accurate diagnostic tools to identify neurodegeneration early on and a long-term monitoring approach for people who have been infected with the SARS-CoV-2 virus. “We found that loss of smell or reduced smell was on average reported in three out of four people infected with the SARS-CoV-2 virus. While on the surface this symptom can appear as little cause for concern, it actually tells us a lot about what’s happening on the inside and that is that there’s acute inflammation in the olfactory system responsible for smell,” says Florey researcher Leah Beauchamp. Inflammation is understood to play a major role in neurodegenerative disease and has been particularly well studied in Parkinson’s. “We believe that loss of smell presents a new way forward in detecting someone’s risk of developing Parkinson’s disease early. Armed with the knowledge that loss of smell presents in around 90 per cent of people in the early stages of Parkinson’s disease and a decade ahead of motor symptoms, we feel we are on the right track,” says Beauchamp. Clinical diagnosis of Parkinson’s disease currently relies on presentation of motor dysfunction, but research shows that by this time 50-70 per cent of dopamine cell loss in the brain has already occurred. “By waiting until this stage of Parkinson’s disease to diagnose and treat, you’ve already missed the window for neuroprotective therapies to have their intended effect,” says Barnham.