Broadcaster Andrew Marr said a new treatment he received after suffering a stroke has resulted in subtle changes, but not the "dramatic improvements" he hoped for.
The BBC presenter, who had a stroke almost four years ago and remains semi-paralysed on his left side, travelled to Florida to try a new anti-inflammatory drug called Etanercept.
Andrew had described the treatment - which involved having the drug injected into his spinal fluid while hanging upside down - as a Christmas present to himself. He said he will now work to build on the small changes he has seen.
Andrew told the Press Association: "Although I haven't seen the dramatic improvements that I hoped for, there have been subtle and useful changes which I am going to work on through physiotherapy and exercise over the coming months.
"It hasn't been 'pick up thy bed and walk' but it hasn't been nothing, either. We will tell the fuller story in a BBC documentary scheduled to be broadcast in January."
Andrew's stroke in January 2013 left him spending two months in hospital and undergoing extensive physiotherapy to help him walk.
In a piece for the Spectator recently, talking about the new treatment, he detailed some of the effects of stroke he has to deal with.
He wrote: "I'm not complaining too much: I can work, drink, see friends, paint, listen to music and irritate my children like before. I'm a lucky fellow.
"But I can't run or cycle or swim, and I walk very unsteadily and slowly. I drop things and take ages to get dressed."