Rescuers say they are still hopeful of finding a man who suffers from Huntingdon's disease who went missing in the Peak District two days ago.
Mr Henshaw's condition may make him appear as if he is drunk
Peter Henshaw, 43, from Barnsley, left Torside Reservoir on Tuesday.
Police said they are concerned about his welfare as he has no food or map with him.
Mountain rescue volunteers are helping officers with the search for Mr Henshaw, who was last seen wearing dark blue shorts and a blue T-shirt.
Three search and rescue dogs, the Forestry Commission and the National Park Ranger Service have also joined officers from South Yorkshire and Derbyshire Police in the search.
A police spokeswoman said they are particularly worried about Mr Henshaw due to his illness.
She said: "He has difficulty communicating and walks with an unusual gait because of his medical condition. This often gives him the appearance of someone who is drunk."
Mr Henshaw had intended to follow the Pennine Way to Edale, where he would catch the train back to Barnsley via Sheffield.
He is described as 6ft tall, clean shaven with mousey brown hair and a Barnsley accent.