Postmenopausal women who took antidepressants had a small increased risk of dying from all causes, compared to women who did not take antidepressants, according to a new finding from the Women’s Health Initiative study. Those who took selective serotonin reuptake inhibitors, or SSRIs, also had a greater risk for strokes, especially strokes caused by bleeding, but their overall risk was still quite small.

The WHI, which began in 1991, followed more than 160,000 postmenopausal women US for up to 15 years. The new analysis included more than 136,000 WHI participants who weren’t taking antidepressants at enrollment, but at their first follow-up visit, either one or three years after enrolling, 5,500 women reported taking either tricyclic or SSRIs, WebMD writes.

Women who took antidepressants had no greater risk for heart disease six years later, but SSRI use was associated with a 32 percent greater risk of dying from all causes in one analysis and a 45 percent increased risk for stroke, WebMD continues, adding the overall increase in stroke risk among SSRI users was less than 2 percent a year. SSRIs include Prozac, Paxil, Zoloft, Lexapro, and Celexa.

It was not clear if the increase was caused by drugs or by depression. “Depression is an often serious and debilitating illness, with its own heart risks including heart disease and death,” study researcher Jordan Smoller of Massachusetts General Hospital tells WebMD. “It is difficult to confidently tease apart the contribution of depression and the drugs used to treat it.”

Also unclear is whether a similar association would be seen in men and younger women. The researchers note tricyclic antidepressants can be toxic to the heart. Studies examining SSRIs and the heart have been mixed, with some finding the drugs to be protective against clot-related strokes and others finding them to increase bleeding risks.