Marjorie Grayson, aged 83, admitted manslaughter on the grounds of diminished responsibility at Sheffield Crown Court.
Grayson fatally stabbed her 85-year-old husband, Allan, at their home in Orgreave Lane, Handsworth on September 13 last year.
Dressed in a blue jumper and red trousers, Grayson spoke only to confirm her name and plea during a 20-minute hearing yesterday.
Mr Justice Nicklin adjourned the case until April 12, to allow for the preparation of a pre-sentence report.
He told Grayson: “There is at least the possibility of imposing a sentence that is not immediate custody. I need to know what that looks like.”
He added: “This a very serious offence. There are particular circumstances in your case that mean I must consider carefully what sentence is the correct sentence to impose.
“Please make sure you cooperate with the probation service, because their report is going to be very important.”
Grayson previously entered a plea of not guilty to the charge of murder, and was due to stand trial on Tuesday.
Dafydd Enoch QC, prosecuting, told the court the lesser charge of manslaughter was acceptable, following medical evidence from psychiatrists.
He said: “The position now is there is a wealth of psychiatric evidence from three different sources which make it clear this woman at the time was suffering from an impairment of behavioural variant frontotemporal dementia.”
Commenting on the investigation, Mr Enoch added: “This is a very, very sad case and from the moment of the sad death of Mr Grayson those investigating have been trying to seek answers as to what it was that could have given rise to these tragic events.”
In a statement submitted to the court from Grayson’s son, Paul, he said the family ‘hoped to be involved with the planning of her future care’.
Grayson was remanded into custody until her next court appearance.