The former CEO of Abercrombie & Fitch (A&F) has dementia and late onset Alzheimer's disease, his legal team has said in a court document filed in New York.
Lawyers for Mike Jeffries have requested a hearing to determine whether he is mentally fit to stand trial on federal sex trafficking charges.
The 80-year-old was arrested alongside his partner in October and charged with running an international sex trafficking and prostitution business. Both men have pleaded not guilty.
A so-called competency hearing has been scheduled for June next year.
Mr Jeffries, who ran US clothing brand A&F for two decades, is accused of running a sex trafficking and prostitution business from at least 2008-15.
US prosecutors allege that he used his wealth, power and status "to traffic men for his own sexual pleasure", and for the pleasure of his British partner Matthew Smith, 61.
They said the couple, alongside a middleman James Jacobson, 71, used force, fraud and coercion to make vulnerable, aspiring models engage in violent and exploitative sex acts.
All three men have pleaded not guilty to the charges and been released on bond.
The FBI began investigating last year after the BBC revealed claims Mr Jeffries and Mr Smith had sexually exploited men at events they hosted around the world.
The BBC investigation, published in October 2023, found the pair were at the centre of a sophisticated operation involving a middleman scouting young men for sex.
In the same month, Brian Bieber, Mr Jeffries' lawyer, said his client was examined several times by a neuropsychologist who later concluded diagnostic impressions that he was suffering from two types of dementia and probable late onset Alzheimer's disease.
In the court filing, Mr Bieber added that during an initial meeting last year the former fashion boss "did not even come close to resembling a master's degree-educated individual, who was just nine years earlier the chief executive officer of a publicly traded company".
As a result, Mr Bieber questioned the ability of Mr Jeffries to "rationally assist" with the possible factual and legal defences to the allegations he was facing, according to the document.
The filing comes after Mr Jeffries' legal team sought a competency hearing, which will now be held over two days on 16 and 17 June 2025.
Federal prosecutors in the Eastern District of New York declined to comment.
Mr Jeffries stepped down as CEO and chairman of A&F in 2014, and left with a $25m (£19.9m) retirement package.
Alongside the criminal case, A&F, Mr Jeffries and his partner have been defending a civil lawsuit accusing the retailer of having funded a sex trafficking operation.
Earlier this month, Mr Jeffries sued A&F after it refused to pay his criminal defence costs, arguing the brand had agreed to indemnify him for all claims arising out of his position.