Former President George H.W. Bush has been diagnosed with pneumonia and suffers from a rare syndrome called vascular parkinsonism, which mimics the effects of Parkinson’s disease. Bush, 92, has been using a wheelchair ever since breaking a vertebra in 2015.

Vascular parkinsonism is characterized by shuffling steps and is the result of small strokes in the brain, but the disease doesn’t include the tremors characteristic of Parkinson’s, and they also don’t repond to drugs meant to treat Parkinson’s. The disease is similar to Parkinson’s mostly from the waist down.

However, it does gradually get worse just like Parkinson’s, resulting in progressive supranuclear palsy and excessive brain fluid. Bush said in an interview with Parade a few years ago that the condition wasn’t painful and just affected the legs. He said it was “strange” when he couldn’t get his legs to move how he wanted them to, but said as far as bad diseases go, this was a “good one to get.”