Robert F. Kennedy Jr. once thought he had a brain tumor but the dark spot on the scans turned out to be a dead parasitic worm, the New York Times has reported citing legal documents.

President John Kennedy’s nephew, who is currently running an independent presidential campaign, has argued that he is both younger and healthier than incumbent President Joe Biden and his chief rival Donald Trump.

In 2010, however, RFK Jr. was experiencing “brain fog” and memory loss so severe, he turned to top neurologists for advice about a possible tumor, according to the Times. One New York doctor gave him a different opinion, however: a dead parasite.

The anomaly seen on the scans “was caused by a worm that got into my brain and ate a portion of it and then died,” Kennedy said in a 2012 deposition.

In the same legal interview, Kennedy said he “clearly” had cognitive problems, including short-term and longer-term memory loss. In a subsequent interview with the Times, however, he attributed those to mercury poisoning, caused by his fish-heavy diet at the time.