Minor infections such as colds could increase the risk of stroke "either through systemic effects of inflammatory mediators causing a prothrombotic state or by direct or indirect effects on arteries through various mechanisms."
Although associated with older people, anyone can have a stroke regardless of age. Stroke is a leading cause of death in children in the US and, according to the National Stroke Association, stroke affects about 6 in every 100,000 children.
Minor infections and inflammatory conditions such as colds have previously been associated with an increased risk of cerebral ischemic stroke in adults. Although the origins of pediatric stroke are slightly different to adult stroke, the effects of colds are similar for both children and adults.
In an editorial linked to the study, Dr. Lars Marquardt of the University of Erlangen-Nuremberg, Germany, writes that "because conventional risk factors are less prevalent in children, inflammatory conditions may be more relevant contributors to stroke risk in children."
Up until now, the association between inflammation and stroke in children has not been studied in depth, and that is why the research team set out to investigate specifically whether the timing and number of minor infections increased the risk of childhood arterial ischemic stroke (AIS).
According to the authors of the study, only a small number of children who are born with recognized stroke risk factors - congenital heart disease, for example - go on to have AIS, leading them to hypothesize that pediatric AIS has multiple causative factors, including potential environmental ones such as exposure to minor infection.
An increased risk?
The researchers reviewed data from the Kaiser Pediatric Stroke Study, a database representing about 2.5 million children within a Californian health care organization.
From this review, they identified 102 children who had an AIS without an associated major infection and 306 children who had not had an AIS to serve as a control group.
The medical records of these children were then investigated for minor infections occurring up to 2 years prior to the AIS. Of the infections that were found, about 80% were respiratory in nature.
The researchers found that the risk of stroke was increased, but only within a 3-day period between a visit to the doctor for signs of infection and the AIS. Of the 102 children that had an AIS, 10 had a doctor visit for an infection within 3 days of the stroke (9.8%).
During the same period, only two children from the control group had an infection (0.7%). Thus, the authors calculate that the children with AIS were 12 times more likely to have had an infection within the previous 3 days.
A higher total number of infections over a 2-year period was not associated, however, with an increased risk of stroke.
Further research required
Dr. Heather Fullerton, one of the authors of the study, said their findings suggest "that infection has a strong but short-lived effect on stroke risk."
"We've seen this increase in stroke risk from infection in adults, but until now, an association has not been studied in children. It is possible that inflammatory conditions contribute more to the stroke risk in children, however, further research is needed to explore this possible association."
The necessity for further research arises from the limitations of the study. Many of the children may not have had a doctor visit for a minor infection. The retrospective nature of the study also meant that the precise timings of infection onset and utilization of medications could not be measured.
Furthermore, there were no laboratory tests available to assess individual infectious burden, and there was no information available on nonprescription medication use, which many have influenced outcomes.
However, despite the inherent limitations of the study, Dr. Marquardt believes that it "provides some interesting possibilities that are worth pursuing." He points out that the relatively short period in which the AIS risk is increased suggests that the prothrombotic effects of minor infections could be of particular importance.
Dr. Marquardt is still keen to impress the fact that the overall risk of stroke among children is extremely low: "Minor infections are very common in children while strokes are thankfully very rare. Parents should not be alarmed whatsoever if a child catches a simple cold."
Previously, Medical News Today reported on a study that children receiving growth hormone treatment could have an increased risk of stroke in early adulthood.