While genetics and biology play a large role in predisposing a person to bipolar disorder, stress is believed to be a significant trigger of bipolar episodes. Margaret says, “Had I gone back to school, had I got involved in a charity or something, I may have been able to keep my sanity. I whiled away, then when I would get out and get away, woo! It was just like a rubber band, from one extreme to the other.”

At Harrington Lake, the prime ministerial country retreat, Margaret was free of stuffy protocol and could occupy herself with housework and cooking. Long before it became trendy, she was a knowledgeable health food enthusiast who grew her own vegetables, an advocate of natural childbirth and an environmentalist who used only cloth diapers on her babies. But whenever she had to return to 24 Sussex Drive and the artifice of being a political wife, she had such difficulty coping with the ensuing depressions that, like many people with mental illness, she used illegal drugs to alter her moods.

“One of my real problems was that with my sadness, I would self-medicate – smoke dope – and I did that for a few years, which didn’t help me one bit,” she says. “It gave me a feeling of euphoria and lifted me up, only to slam me down. It’s no solution.”

Pierre, who famously lived by the motto Reason Over Passion, became increasingly confused and frustrated by Margaret’s behaviour. “He was bewildered,” she says. “He wasn’t unkind or anything. He thought that maybe it was a character flaw in me, that I lacked discipline or something, or maturity. Later on in life, he was very compassionate. But when we were together, he didn’t understand that it was a disease I was battling.” Nor did the Canadian public, who shook their collective heads and lamented, “What will Maggie come out with next?”

Following the birth of Sacha, Margaret developed postpartum depression, which is linked with bipolar disorder and in some women may be the first manifestation of the disease.

“Depression is more than sadness,” Margaret says. “It’s a mental condition that robs you of your hope, robs you of feeling that things are going to get better.” Despite her depression, she weaned Sacha overnight so she could embark on a cross-country election campaign with Pierre, keeping a gruelling schedule that would tax even a healthy person. The Liberals won the 1974 election – a win that was at least partly attributed to Margaret’s genuine warmth and connection with her audiences.

Then came Margaret’s first climb into mania. She used to call her manic episodes “rebellions” or “freedom trips”; now she knows they were part of the disease. There are two kinds of mania, she explains: hypomania, an exaggerated “high” that can feel wonderful after a depression but is actually a warning sign; and true mania, where the elevated mood spins out of control. Margaret says, “The symptoms of mania – and I just had the normal symptoms – are a feeling of power, immortality, invincibility, not taking any advice from anyone, not getting any sleep, go-go-go, talking too much and not facing the consequences of your actions. Sexual promiscuity, feeling very, very sexual, is a big one, and the other one is spending money recklessly. Everyone wants to be a bit manic. It’s exciting. It’s fun. But it escalates into madness, where you’re not making any sense anymore.”