Here, we show that overexpression of SARS-CoV-2–encoded nonstructural protein 1 (Nsp1) robustly rescued neuromuscular degeneration and behavioral phenotypes in Drosophila models of Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. The gene discussed is SH2D3A; the disease is early-onset autosomal dominant Alzheimer disease.