American diplomats’ brains shrunk following an alleged sonic attack on the US Embassy in Cuba, according to a new study.

State-of-the-art imaging of staff members who suffered headaches, nausea and memory loss after hearing mysterious noises reveals “significant” structural changes, scientists have revealed.

Blame for the spate of unusual symptoms that afflicted diplomats at the Havana embassy between late 2016 and May 2018 has ranged from a deliberate attack using a mysterious sonic weapon to an abundance of crickets.

More than 20 American staff members complained of hearing penetrating noises in their homes or nearby hotels.

The real cause of the symptoms has not yet been established, although State Department officials have previously referred to a “sonic attack” and “directional phenomena”.

The illnesses prompted the US to more than halve its numbers at the mission in 2017.

Relations further soured after two Cuban diplomats were expelled from Washington and Donald Trump said he held the Caribbean nation responsible.

Fourteen Canadian diplomats posted to Havana also reported symptoms, five of whom are suing their government for millions of dollars in compensation.

Published in the Journal of the American Medical Association, the study took detailed images of the electrical functioning of 40 staff members and compared them to those of healthy participants who were matched for age and background.