A new study may help predict which patients with early Parkinson’s disease will experience hallucinations, sleepiness, or swelling.

Identifying the risk factors may better guide which treatment is more suited for the patient, allow for earlier intervention and reduce disabilities, according to study author Dr. Keven Biglan, University of Rochester, NY.

The 4-year study of 301 Parkinson’s patients revealed that 1 out of 5 developed hallucinations, while almost half developed swelling within four years of starting treatment with either levodopa or pramipexole.