The 52-year-old woman suffers from Huntington’s disease, which affects muscle coordination and the brain.
She was walking southwards along West Granton Road in Edinburgh towards the Morrison store between 10.30am and 11.20am yesterday (Thursday) when someone approached her from behind.
The suspect grabbed hold of the woman’s handbag strap and pulled on it violently, causing her to fall to the ground.
The individual then made off with the bag, which contained cash and other personal possessions, towards Pennywell Road where they were lost to sight.
Two passers-by then came to the victim’s aid and she was taken to the ERI where she is currently being treated for a dislocated shoulder.
Detectives are now keen to speak with anyone who was in the area yesterday morning and remembers seeing anything suspicious.
The suspect is described as white, around 5ft tall with a skinny build. They were wearing a dark hooded top with the hood worn up concealing their face and dark trousers.
A police spokesman said: “This was a sickening and opportunistic assault and robbery on a clearly vulnerable woman and we are carrying out enquiries in the local area to identify the person responsible.
“As the victim did not get a good look at the suspect we are unable to say at this time if they were male or female and would urge anyone who witnessed this incident to come forward and assist with our enquiries.
“We believe a number of cars may have been driving past during the time of the attack and these motorists are asked to contact police immediately.”