Sergeant Steven Turner, from Adur and Worthing neighbourhood police team, said: “Doris suffers from dementia and her family are very concerned for her welfare.
Officers are currently on the ground searching for her and checking with local residents and businesses. We also have support from the police helicopter.
“Doris was last seen around midday at Barclays bank at Southwick Square. She uses the aid of a walking frame and we believe she has this with her. If you see Doris please dial 999 immediately we need to return her to her family as soon as possible.”
Doris is described as white with grey hair and is of small build. She was last seen wearing a white jumper.