Suffering from cold sores could cause 'impaired' memory and thinking skills ple who suffer from cold sores could have 'impaired' memory and thinking skills People were tested for herpes, cytomegalovirus, respiratory chlamydia and Helicobacter pylori Those people who tested positive were 25 per cent more likely to have impaired memory and thinking skills Link was strongest among women, those with lower levels of education and those who do not exercise Cold sores may increase the risk of impaired memory and thinking skills, new research suggests. The herpes simplex virus that causes cold sores is one of a number of infectious agents associated with reduced mental ability. Scientists tested the thinking and memory of 1,625 people from New York City with an average age of 69. Participants had their blood tested for five common infections - oral and genital herpes, cytomegalovirus, the respiratory form of chlamydia, and the stomach bug Helicobacter pylori. Cold sores may increase the risk of impaired memory and thinking skills They found that those with higher levels of infection in the blood were 25 per cent more likely to deliver low score results in a standard mental function test. Repeated tests over an average of eight years showed no sign of the effect worsening with time. The findings appear in the latest issue of the journal Neurology. Study leader Dr Mira Katan, from Columbia University Medical Centre in New York, said: "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. 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. For example, exercise and childhood vaccinations against viruses could decrease the risk of memory problems later in life. This research comes just after another study which suggested that undertaking physical activity four or more times a week from childhood helps improve brainpower in later life by up to a third, and could help stave off the onset of dementia. Exercise and childhood vaccinations against viruses could decrease the risk of memory problems later in life While all adults suffer mental decline with greater age, scientists at King's College London found regular exercise, such as playing sport, jogging, attending the gym or even a brisk walk with the dog, can have a protecting effect on the brain.