From that point on, her memory gradually worsened until she was officially diagnosed in 1985 with multi-infarct dementia, although some descriptions of her life assume she had been diagnosed with Alzheimer's disease. However, at that time such a conclusion could only be confirmed by an autopsy after death. Stephen cared for Joyce at home until 1992, when she was moved into the Fairlawn Nursing Home in Lexington, Massachusetts. She died there from cardiac arrest on August 23, 1994 at the age of 76. She was buried in Mount Auburn Cemetery in Cambridge, Massachusetts.