Posts tagged infections

A new study suggests that colds and other minor infections may temporarily increase stroke risk in children. The study found that the risk of stroke was increased only within a three-day period between a child’s visit to the doctor for signs of infection and having the stroke.

The study was led by researchers at UCSF Benioff Children’s Hospital San Francisco in collaboration with the Kaiser Permanente Division of Research.

“These findings suggest that infection has a powerful but short-lived effect on stroke risk,” said senior author Heather Fullerton, MD, a pediatric vascular neurologist and medical director of the Pediatric Brain Center at UCSF Benioff Children’s Hospital San Francisco.

“We’ve seen this increase in stroke risk from infection in adults, but until now, an association has not been studied in children.”

Strokes are extremely rare in children, affecting just five out of 100,000 kids per year. “The infections are acting as a trigger in children who are likely predisposed to stroke,” said Fullerton. “Infection prevention is key for kids who are at risk for stroke, and we should make sure those kids are getting vaccinated against whatever infections – such as flu - that they can.”

The study appears in the August 20, 2014, online issue of Neurology.

In the study, researchers reviewed a Kaiser Permanente database of 2.5 million children and identified 102 children who had an ischemic stroke – a stroke that occurs as a result of an obstruction within a blood vessel supplying blood to the brain - without a major infection such as meningitis or sepsis. The researchers then compared them with 306 children without stroke. Medical records for the group of children who had a stroke were reviewed for minor infections up to two years before their strokes.

The study found that the risk of stroke was increased only within a three-day time frame, which the researchers say represents a period of acute inflammation. As an infection resolves, the inflammation decreases, as does the stroke risk.

A total of 10 of the 102 children who had a stroke had a doctor visit for an infection within three days of the stroke, or 9.8 percent, while only two of the 306 control participants, or 0.7 percent, had an infection during the same time period.

The children who had strokes were 12 times more likely to have had an infection within the previous three days than the children without strokes. The total number of infections over a two-year period was not associated with increased stroke risk. About 80 percent of the minor infections identified by the researchers were upper respiratory.

“It’s important the public does the things we can to prevent infection, like vaccinations, good hand washing and covering your mouth when you sneeze in order to protect all children, but it’s especially important to help prevent stroke in someone who is otherwise predisposed,” said Fullerton.

(Source: ucsf.edu)

Increased inflammation following an infection impairs the brain’s ability to form spatial memories – according to new research. The impairment results from a decrease in glucose metabolism in the brain’s memory centre, disrupting the neural circuits involved in learning and memory.

Inflammation has long been linked to disorders of memory like Alzheimer’s disease. Severe infections can also impair cognitive function in healthy elderly individuals. The new findings published in the journal Biological Psychiatry help explain why inflammation impairs memory and could spur the development of new drugs targeting the immune system to treat dementia.

In the first trial to image how inflammation impairs human memory, the team at Brighton and Sussex Medical School scanned 20 participants before and after either a benign salty water injection or typhoid vaccination, used to induce inflammation. Positron emission tomography (PET) was used to measure the effects of inflammation on the consumption of glucose in the brain and after each scan participants tested their spatial memory by performing a series of tasks in a virtual reality.

A reduction in glucose metabolism within the brain’s memory centre, known as the Medial Temporal Lobe (MTL), was seen following inflammation. Participants also performed less well in spatial memory tasks, an effect that appeared to be directly mediated by the change in MTL metabolism.

"We have known for some time that severe infections can lead to long-term cognitive impairment in the elderly. Infections are also a common trigger for acute decline in function in patients with dementia and Alzheimer’s disease," explains Dr Neil Harrison, a Wellcome Trust Intermediate Clinical Fellow at BSMS who led the study. "This study suggests that catching a cold or the flu, which leads to inflammation in the brain, could impair our memory."

Infections are unlikely to cause long-term detrimental impact in the young and healthy but the findings are of great significance in the elderly. The team now plan to investigate the role of inflammation in dementia, including insight into how acute infections such as influenza influence the rate of progression and decline.

"Our findings suggest that the brain’s memory circuits are particularly sensitive to inflammation and help clarify the association between inflammation and decline in dementia," says Dr Harrison. "If we can control levels of inflammation, we may be able to reduce the rate of decline in patients’ cognition."

(Source: eurekalert.org)

The virus that causes cold sores, along with other viral or bacterial infections, may be associated with cognitive problems, according to a new study published in the March 26, 2013, print issue of Neurology®, the medical journal of the American Academy of Neurology.

The study found that people who have had higher levels of infection in their blood (measured by antibody levels), meaning they had been exposed over the years to various pathogens such as the herpes simplex type 1 virus that causes cold sores, were more likely to have cognitive problems than people with lower levels of infection in the blood. “We found the link was greater among women, those with lower levels of education and Medicaid or no health insurance, and most prominently, in people who do not exercise,” said author Mira Katan, MD, with the Northern Manhattan Study at Columbia University Medical Center in New York and a member of the American Academy of Neurology. The study was performed in collaboration with the Miller School of Medicine at the University of Miami in Miami, FL.

For the study, researchers tested thinking and memory in 1,625 people with an average age of 69 from northern Manhattan in New York. Participants gave blood samples that were tested for five common low grade infections: three viruses (herpes simplex type 1 (oral) and type 2 (genital), and cytomegalovirus), chlamydia pneumoniae (a common respiratory infection) and Helicobacter pylori (a bacteria found in the stomach).

The results showed that the people who had higher levels of infection had a 25 percent increase in the risk of a low score on a common test of cognition called the Mini-Mental State Examination.

The memory and thinking skills were tested every year for an average of eight years. But infection was not associated with changes in memory and thinking abilities over time.

“While this association needs to be further studied, the results could lead to ways to identify people at risk of cognitive impairment and eventually lower that risk,” said Katan. “For example, exercise and childhood vaccinations against viruses could decrease the risk for memory problems later in life.” The study was supported by the National Institutes of Neurological Disorders and Stroke (NINDS), the Swiss National Science Foundation and the Leducq Foundation.