A family says they are working tirelessly to find their 79-year-old relative who they believe has dementia.

Constance Barrett went missing on Wednesday.

Patricia and Bernard Willie, Barrett's daughter-in-law and son, respectively, have been going door to door, asking business owners if they can leave a sign in the storefront windows. The two live in Florida but are visiting family in the Bronx.

They say they were joking around, having a normal conversation Wednesday, when Barrett snuck out at some point. The two immediately left the apartment and searched the block and surrounding area.

Barrett was last seen around 1 p.m. Wednesday at the 219th Street train station, where the Nos. 2 and 5 lines run on White Plains Road. An MTA employee says she saw Barrett get on the No. 2 train heading southbound toward Manhattan.

Police say Barrett is 5 feet tall and 90 pounds, with gray hair and a birthmark above her left lip. She was last seen wearing a beige, leopard-print jacket, pink pants and pink shoes.

Anyone with information can call Crime Stoppers at 1-800-577-TIPS.