Impact of COVID‑19 infection in patients with neurodegenerative diseases with particular focus on Alzheimer's and Parkinson's disease.

Neurodegenerative disorders (NDD) are chronic neurological diseases characterized by loss and/or damage to neurons along with the myelin sheath, and patients are at higher risk of severe infection with the SARS‑CoV‑2. A comprehensive literature search was performed using relevant terms and inclusion‑exclusion criteria. Recent articles, subjects older than 50 years, and articles written in the English language were included, whereas letters to the editor and articles related to pregnant women were excluded from the review study. COVID‑19 appears to damage angiotensin‑II receptors which cause natural killer cells to lose the ability to clear virus‑infected cells, owing to worse outcomes in patients with NDD. COVID‑19 can worsen the symptoms of Alzheimer's disease. In addition, COVID‑19 worsens drug‑responsive motor symptoms in Parkinson's disease (PD) and other symptoms like fatigue and urinary complaints. Vitamin D is essential in decreasing pro‑inflammatory and increasing anti‑inflammatory cytokines in ongoing COVID‑19 infections and reducing angiotensin receptors and, hence, decreasing COVID‑19 infection severity. Telemedicine shows promise for patients with NDD but is yet to overcome legal issues and personal barriers. COVID‑19 has a significant effect on neurodegenerative conditions, which appears partly to the nature of the NDD and the neuro‑invasive capabilities of the SARS‑CoV‑2. The protective role of vitamin D in patients with NDD further supports this hypothesis. Modifications in current health care, like the telemedicine platform, are required to address the increased risk of serious infection in this population. Further studies will be required to clarify conflicting reports in many fields.