No disease-modifying therapy has been established for spinocerebellar degeneration and multiple system atrophy, and only symptomatic therapy is currently available. Taltirelin and protirelin are drugs covered by health insurance for cerebellar ataxia symptoms, and are expected to suppress the progression of symptoms. Muscle relaxants are used for spasticity associated with spinocerebellar degeneration, and vasopressors and therapeutic agents for dysuria are used for autonomic symptoms of multiple system atrophy. It is necessary to develop a new therapeutic agent with a different mechanism of action, aimed specifically at modifying the disease progression in patients with spinocerebellar degeneration and multiple system atrophy.