She also had polyarthritis, which would have caused chronic pain, and had recurrent mental health problems, which started in 1988 when her first overdose and attempted suicide was recorded.
Two more attempted suicides were also noted in medical records.
Dr Duff said suicide by fire was very rare.
Huao Matangi Wawatai, Wawatai's father, told the court his son was right-handed and had been unable to cut firewood for "a long time" due to hip problems.
Mr Wawatai said his son and Ms Akuhata had been "inseparable" during their relationship.
A written statement from witness and Tikitiki firefighter Patrick Tangere was read to the court. It said the defendant immediately told him Ms Akuhata was in the burning house.
Defence counsel Adam Simperingham said the statement was read to rebut a suggestion that Wawatai had delayed telling firefighters Ms Akuhata was in the house. In his closing address Mr Simperingham said the Crown was basically asking the jury to "speculate" on what happened.
The couple had been in a loving relationship for 32 years and the defendant had no motive to kill Ms Akuhata. The Crown's suggestion that she had packed a bag to leave was "complete speculation".
Although Wawatai did not give evidence in the trial, he was perfectly entitled to do that, he said.
He had already been "honest" and "straight-up" with police.
In the Crown's closing address, Steve Manning said Ms Akuhata had been planning for the future and was not suicidal.
"She was future-thinking, forward-planning and happy."
"Death by fire is a very painful death and fear of fire is a very innate fear for humans. It is a particularly horrible way to die."
There was nothing about the day or weeks leading up to October 10 that showed she was considering killing herself in the "most painful, the most horrible way you can think of".
The defendant had been angry with the deceased and had made admissions to police that he might have gone into the bedroom with a match after he poured petrol on the bed.
The deceased's body was found with car keys and DNA tests showed she had been clothed. That indicated she had been trying to get away from the defendant, he said.
"There were only two people who were home that night and one was angry. Anger prevailed.
"In anger he has poured petrol around his own bedroom. She tried to leave, he has tried to stop her and in a rage he has set a fire."
Ms Akuhata had not been prescribed medication for depression for more than two years prior to her death.
The defendant had given contradictory statements to police officers. Trying to place blame on the deceased was "the final indignity".
Mr Simperingham said while reconstruction of past events in this case was difficult, he advised the jury to apply the "robust use of common sense."
