The alleged sonic attack that occurred in Havana, Cuba in 2016 might have changed the brains of affected government personnel from the United States.

A team from the University of Pennsylvania analyzed the MRI brains scans of 40 people (23 men and 17 women) who were afflicted by what had been dubbed as the "Havana syndrome." The researchers compared the brain scans to 48 other adults. The MRI brain scans were taken between August 2017 and June 2018.

They published their findings in JAMA on Tuesday, July 23.

Scientists Notice Brain Differences After Alleged Sonic Attack

"The areas implicated in the patients' brains, namely the cerebellum as well as the visuospatial and auditory networks, align with the neurological symptoms that were observed in the patients," explained Ragini Verma, a professor of Radiology and the lead author of the study. "These differences persisted even when people with some history of brain injury were excluded from the analysis."

In late 2016, diplomats and their families reported experiencing symptoms such as dizziness, visual issues, balance issues, and difficulty with memory and concentration. Many said they heard loud buzzing or humming noises coming from one direction.

The researchers noted that the differences in the imaging brain scans of the people affected by the mysterious incident have not been observed before.

"It certainly does not resemble the imaging presentation of traumatic brain injury or concussion, although they present with clinical symptoms which are concussion-like," Verma said in the report by CNN. "It says something happened, and we need to look further, and that's about it."

The researchers, however, warned that the clinical importance of their findings is uncertain. They noted that they did not have the MRIs of patients to compare with before the incident happened.

Was It A Sonic Attack?

Over a year after the alleged sonic attack in Havana, the specifics remain a mystery. An audio recording related to the incident was obtained by the Associated Press and released to the public in October. However, a pair of scientists said that the sounds resemble the chirping of crickets found in the island.

Cuban officials have vehemently denied allegations of sonic attack that also affected diplomats from Canada.