The officers were leaving when neighbors said a young child who lived in the house would be left unattended; the officers said they had seen no signs of a child.
But as they looked further, the officers and a supervisor found the woman in the basement, bound to a bed in what police described as "unsuitable conditions."
She was extremely thin and had sores on her body, a police spokeswoman, Officer Tanya Little, said.
"She appeared to be special-needs and has a limited vocabulary," Little said.
The woman was cut free from the bed and taken to Einstein Medical Center, where she was being evaluated later Saturday. Police did not describe her condition.
Her relationship to the woman who was arrested had not been determined, Little said.
Charges related to the woman's condition had not been filed Saturday evening, but the investigation continues.
Contact Jonathan Lai at 856-779-3220, firstname.lastname@example.org, or follow on Twitter @elaijuh.