Depressed middle-aged women have almost double the risk of suffering a stroke, according to research.
A 12-year Australian study of 10,547 women 47-52 years old found that depressed women had a 2.4 times increased risk of stroke compared to those who were not depressed.
Even after researchers eliminated several factors that increase stroke risks, depressed women were still 1.9 times more likely to have a stroke.
The findings are published in Stroke: Journal of the American Heart Association.
Study author Caroline Jackson, an epidemiologist in the School of Population Health at the University of Queensland in Australia, said: "When treating women, doctors need to recognise the serious nature of poor mental health and what effects it can have in the long term. Current guidelines for stroke prevention tend to overlook the potential role of depression."
This is the first large-scale study in which researchers examined the association between depression and stroke in younger middle-aged women.
The closest comparison is with the US-based Nurses' Health Study, which found a 30% higher risk of stroke among depressed women. However, the average participant's age in the Nurses' study was 14 years older.
Dr Jackson and her colleagues analysed survey results from the nationally representative Australian Longitudinal Study on Women's Health. Participants answered questions about their mental and physical health and other personal details every three years in 1998-2010.
Researchers eliminated various characteristics that can affect stroke risks, including age, socioeconomic status, lifestyle habits such as smoking, alcohol and physical activity, and physiological conditions including high blood pressure, heart disease, being overweight and diabetes.
Although the increased stroke risk associated with depression was large in the study, the absolute risk of stroke is still fairly low for this age group, Dr Jackson said.
About 2.1% of American women in their 40s and 50s suffer from stroke. In the study, only about 1.5% of all women had a stroke.
Dr Jackson said: "We may need more targeted approaches to prevent and treat depression among younger women, because it could have a much stronger impact on stroke for them now rather than later in life."
It is unclear why depression may be strongly linked to stroke in this age group. The body's inflammatory and immunological processes and their effects on the blood vessels may be part of the reasons, she said.