Nichelle Nichols, best known for playing Lieutenant Uhura in “Star Trek,” has been diagnosed with dementia.

According to Nichols’ conservatorship documents obtained by TMZ, the 85-year-old has “moderate progressive dementia.”

Dr. Meena Makhijani, who’s been treating the actress for the last few years, says she has a major impairment in short-term memory and moderate impairment when it comes to abstract concepts, time, place and recall.

However, the gossip site reports her long-term memory, comprehension, verbal communication, concentration and recognition of familiar people is fine.

In 2015, Nichols suffered a mild stroke at her home.

A rep for the actress did not immediately return a request for comment.