In childhood, the rates of depression in girls and boys are identical. For seniors, the rates of depression among women and men become similar as they age.
But between puberty and menopause, depression is predominantly a woman's illness, with rates two times higher - or more - than men.
That's pretty strong evidence that hormones are to blame, isn't it?
"Hormones do play a role, but it would be a big mistake to attribute everything to hormones," says Donna Stewart, the Lillian Love chair of women's health at University Health Network and the University of Toronto. "It's a lot more complicated than that."
As a clinician, Dr. Stewart hears a recurring sentiment from patients suffering from clinical depression: "I don't have any time for myself."
The trigger for depression in women tends to be stress, generally provoked by time pressure and relationship challenges.
"The social expectations around women today are enormous, particularly in their reproductive years," Dr. Stewart says. "Many women today work double and triple workloads as mothers, caregivers and paid workers.
"Of course, this is going to have an impact on their health - their physical and mental health," she says.
Another factor in the higher rates of depression is that women have a more ruminative cognitive style: They second-guess themselves and internalize their emotions.
When men are stressed and depressed, they act out. They drink more, eat less, sleep less, lash out and are reckless. In the extreme, they commit suicide.
Women sleep more and eat more. They become more cautious and much harder on themselves. They cry out for help with suicide attempts.
(In women there are up to 20 suicide attempts for each completed suicide; in men, four attempts for every completed act.)
Juniper Glass, development director for the Montreal-based Girls Action Foundation, says rates of anxiety and depression and suicide attempts are highest in the 15-to-24 female age group - supposedly their carefree years.
"Why is this happening?" she asks. "Why are girls suffering descending levels of self-confidence and self-esteem and soaring rates of stress as they grow up?"
A fundamental problem, Ms. Glass says, is ever-growing expectations - to look good, to be good, to succeed at everything - coupled with gender stereotyping. "Girls are still taught to be girls. They blame themselves and turn their dissatisfaction inwards. ... That's the root of a lot of depression."
While boys are encouraged to be active, to play sports, to party, girls often don't have an outlet. So the Girls Action Foundation supports programs where girls can express themselves through art, sports or community activities and develop leadership skills.
"We can't take away all the stresses in their lives, but we can support their strengths, and we can give them skills to navigate the pressures," Ms. Glass says.
Dr. Stewart says grown women need to find coping mechanisms too. "The lack of work-life balance is a huge factor underlying depression."