Some people who have a stroke may have increased symptoms of depression in the years leading up to it, new research suggests.
Scientists say their findings indicate slight increases in depressive symptoms might be a signal that a stroke is about to occur.
While depression is a common problem for people who have already had a stroke, the study suggests it is not only a post-stroke issue, but also a pre-stroke phenomenon.
Study author Maria Blochl, of the University of Munster in Germany, said: “Depression is among the most pressing problems in people who have had a stroke and it is so common it is referred to as post-stroke depression. “But our study found depressive symptoms not only markedly increase after stroke, it found people already had developed some depressive symptoms before the stroke even occurred.”
Researchers looked at 10,797 adults with an average age of 65 and without a history of stroke at the start of the study.
They were followed for up to 12 years, and during that time, 425 people had a stroke.
They were matched with 4,249 people who did not have a stroke.
Every two years people were asked if they experienced symptoms of depression in the past week, including feeling depressed, feeling lonely, feeling sad, feeling that everything was an effort, and restless sleep.
The more symptoms they had, the higher their score.
The study found that six years before the time of the stroke, those who later had a stroke and those who did not, had similar scores.
However, about two years before the stroke, scores of people who had a stroke started increasing.
After a stroke, depressive symptoms increased and stayed high for a decade years after the stroke.
In contrast, the scores of people who did not have a stroke remained roughly the same throughout the study.
According to the study, at the assessment before the stroke, 29% of people who were about to have a stroke met the criteria for having probable depression, compared to 24% of those who did not have a stroke.
But at the time of the stroke, 34% of the people met the criteria for having probable depression, compared to 24% of those who did not have a stroke.
Ms Blochl said: “This suggests that increasing symptoms of depression before stroke are mostly subtle changes and may not always be clinically detectable.
“But even slight increases in depressive symptoms, especially mood and fatigue-related symptoms, may be a signal a stroke that is about to occur.”
She added: “Whether these pre-stroke changes can be used to predict who will have a stroke is unclear.
“Exactly why depressive symptoms occur pre-stroke needs to be investigated in future research.
“Also, the study underscores why doctors need to monitor for symptoms of depression long term in people who have had strokes.”
The findings are published in the Neurology journal.