Though unable to speak otherwise, an elderly man with advanced Alzheimer’s disease nonetheless breaks his silence when exposed to “pet therapy” — a tail-wagging dog named Roscoe. In a YouTube video below, Lisa Abeyta captures an emotional moment as her father experiences a brief remission of sorts, speaking and cooing to the dog.

"Oh yeah, hey! You've got, you've got something! You've got something, huh?" he says to Roscoe. "Yeah, well, that ... that's too bad, there. That's all. That's all I've got."

Even with advanced cognitive impairment, something as basic as playing with the family dog brought Abeyta’s father back to life, in a therapeutic tradition dating back to the 1980s. Today, animal-assisted therapy is used to improve a patient’s social, emotional, and cognitive functioning.

According to the National Institute on Aging, some 5.1 million Americans may suffer from Alzheimer’s disease, the most common form of dementia among elderly people. The condition encompasses a loss of cognitive and behavioral functioning, becoming a debilitating impediment to independent living. For most people, symptoms first appear after the age of 60. The disease is named for Alois Alzheimer, a doctor who first found amyloid plaques and neurofibrillary tangles, which cause neuronal dysfunction, by performing an autopsy on a patient in 1906.