Infections Linked to Stroke
< Nov. 11, 2009 > -- A new study suggests that being exposed to several common pathogens may contribute to the risk for having a stroke.
The researchers found that the bacteria Chlamydia pneumoniae and Helicobacter pylori and the viruses cytomegalovirus and herpes simplex virus 1 and 2 may be implicated in accelerating arterial disease, which in turn increases the risk of stroke.
The study, led by Dr. Mitchell Elkind, an associate professor of neurology at Columbia University Medical Center in New York City, appears online this week in the Archives of Neurology.
Strokes occur when there is a disruption in the blood supply to the brain, such as a blockage in an artery or other blood vessel. When this happens, brain cells begin to die, causing brain damage and even death. Common functions affected or lost during a stroke include speech, movement, and memory.
Stroke is the third-leading cause of death in the US, according to the National Stroke Association (NSA). Strokes have many causes, but it is widely known that certain risk factors increase the chances of having a stroke. These include high blood pressure, diabetes, high cholesterol, smoking, and obesity.
Seeking Connection Between Inflammation and Blood Vessel Problems
"These are infections that regularly pop up when we study heart disease," says Dr. Elkind. "They are very common in the population."
Scientists are not completely sure how the pathogens harm arterial function, but several theories offer suggestions. One possibility is that chronic infection leads to inflammation in the blood vessels, which can constrict blood flow. Another possibility, Dr. Elkind says, is that the pathogens disrupt the normal functioning of the arterial walls.
In recent years, evidence has been uncovering the role of pathogens in cardiovascular disease, particularly the pathogens featured in Dr. Elkind's research. Scientists reported several years ago that untreated gum disease and other oral infections can spread and cause heart disease.
Dr. Elkind's study tracked 1,625 adults from a multi-ethnic community in Manhattan for 7.6 years. During that time, 67 patients suffered a first stroke. Even taking into account other risk factors, such as high blood pressure and diabetes, the researchers found that the majority of the patients tested positive for one or more of the suspected pathogens.
"Each individual infection was positively, though not significantly, associated with stroke risk after adjusting for other risk factors," the researchers wrote in the journal article. "The infectious burden index was associated with an increased risk of all strokes after adjusting for demographics and risk factors."
Further Study Needed
It is too early to tell which pathogens contributed to the strokes, to what extent they contributed, and how they contributed (through simple exposure or chronic infection), says Dr. Elkind. Furthermore, there may be other pathogens involved that were not included in the study, he adds.
It is also too early to make any clinical recommendations. If scientists conclusively determine that pathogens are capable of causing strokes years after people come in contact with them, possible treatments may include wider and longer use of antibiotics, states Dr. Elkind.
Dr. Kishore Ranade, a neurologist affiliated with the Mount Kisco Medical Group in New York, says he is impressed with the findings. He suspects that pathogens work with other risk factors to cause strokes.
"Cumulative data have been suggesting that pathogens play a role in heart disease in general," says Dr. Ranade. "And what's bad for the heart is bad for the brain."
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What is Stroke?
Stroke, also called brain attack, occurs when blood flow to the brain is disrupted. Disruption in blood flow is caused when either a blood clot or piece of plaque blocks one of the vital blood vessels in the brain (ischemic stroke), or when a blood vessel in the brain bursts, spilling blood into surrounding tissues (hemorrhagic stroke).
The brain needs a constant supply of oxygen and nutrients in order to function. Even a brief interruption in blood supply can cause problems. Brain cells begin to die after just a few minutes without blood or oxygen. The area of dead cells in tissues is called an infarct. Due to both the physical and chemical changes that occur in the brain with stroke, damage can continue to occur for several days. This is called a stroke-in-evolution.
A loss of brain function occurs with brain cell death. This may include impaired ability with movement, speech, thinking and memory, bowel and bladder, eating, emotional control, and other vital body functions. Recovery from stroke and the specific ability affected depends on the size and location of the stroke. A small stroke may result in only minor problems such as weakness in an arm or leg. Larger strokes may cause paralysis (inability to move part of the body), loss of speech, or even death.
According to the National Stroke Association (NSA), it is important to learn the three Rs of stroke:
Stroke is an emergency and should be treated as such. The greatest chance for recovery from stroke occurs when emergency treatment is started immediately.
Consider the following statistics regarding strokes:
Always consult your physician for more information.
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