(By David DiSalvo)
“Infections can affect the brain directly, but also through peripheral inflammation, which affects the brain and our mental capacity. Infections have previously been associated with both depression and schizophrenia, and it has also been proven to affect the cognitive ability of patients suffering from dementia.”
To the already long list of reasons to avoid a hospital stay, a new study adds one that will make you think – or potentially impair your ability to think. Researchers have uncovered a strong correlation between hospitalized infections and lower IQ scores.
The study used an enormous amount of tracking data on 190,000 Danish citizens born between 1974 and 1994, all of whom had their IQ assessed. About 35% of those people spent time in hospitals for various infections before they took IQ tests.
The results showed that people hospitalized once tested out with IQ scores 1.76 points lower than average. And people with five or more hospitalizations for different infections tested 9.44 points lower than average. The closer the hospitalization was to when the person took the IQ test, and the more serious the infection, the lower the score.
“The study thus shows a clear dose-response relationship between the number of infections, and the effect on cognitive ability increased with the temporal proximity of the last infection and with the severity of the infection. Infections in the brain affected the cognitive ability the most, but many other types of infections severe enough to require hospitalization can also impair a patient’s cognitive ability,” according to lead-study author Dr. Michael Eriksen Benrós.
“Moreover, it seems that the immune system itself can affect the brain to such an extent that the person’s cognitive ability measured by an IQ test will also be impaired many years after the infection has been cured.”
Now, it’s important to note that there are often big problems with correlational studies like this. It’s notoriously difficult to control for other factors that might play a role in the result. In this case, the authors took precautions to control for anything aside from infections, but admit that they (and no one conducting these sorts of studies) could catch all of them, including hereditary factors that affect IQ.
Having said that, the correlation between the number of infections and a big drop in IQ scores (compared to average scores) is hard to ignore. Equally so, the correlation between severity of infection and IQ drop is significant.
Infections serious enough to require hospitalization could affect the brain in a few different ways, according to Benrós. “Infections can affect the brain directly, but also through peripheral inflammation, which affects the brain and our mental capacity. Infections have previously been associated with both depression and schizophrenia, and it has also been proven to affect the cognitive ability of patients suffering from dementia.”
It’s hard to not view these findings against the backdrop of the vaccination debate. It would seem that failing to protect children from serious infections, like measles, may not only compromise their immediate physical health but potentially also their cognitive abilities well into their lives.
The study was published in the journal PLOS ONE.