It is common for people to experience mental sluggishness during an illness. This symptom has a possible physical cause, according to a new study.
Researchers at the University of Birmingham, in collaboration with their counterparts from the University of Amsterdam, reported in a study that inflammation may be responsible for reduced mental alertness while being ill.
Findings from the new research were recently published in the journal NeuroImage.
Some scientists think that inflammation has a link to cognitive issues. However, explaining the cause and effect has proven difficult.
“For example, people living with a medical condition or being very overweight might complain of cognitive impairment,” said Dr. Ali Mazaheri, a study senior author, “but it’s hard to tell if that’s due to inflammation associated with these conditions or if there are other reasons.”
The researchers, therefore, set out to investigate what effects inflammation can have on cognition.
Many of the people with a chronic medical condition often report considerable mental fatigue. This symptom, which may be as severe as the main condition, is commonly described as brain fog or mental sluggishness.
Finding the link between inflammation and brain activity
Inflammation is the body’s natural response to illness. It is helpful when it is not of a chronic nature.
Researchers in this study directed attention mainly to a brain region that is in charge of visual attention. They recruited 20 young men for their study and gave them a vaccine for Salmonella Typhi.
The use of this vaccine results in temporary inflammation, among a few other side effects.
After receiving the vaccine, the cognitive responses of the male volunteers were assessed using images on a computer monitor. The aim of this test was to find out how well the subjects could control their attention.
While the attention tests were going on, researchers evaluated the brain activity of the volunteers.
The subjects also got a placebo injection (with water) on another day, either before or after. The same tests were carried out as well.
Now, the volunteers had no idea whether they got a vaccine or placebo injection on test days. Researchers took blood samples on each day to assess the subjects’ levels of inflammation.
Reduced mental alertness
Tests in this study were designed to evaluate three processes related to attention and involving separate portions of the brain. The processes were: alerting, orienting, and executive control.
The “alerting” process is about attaining and preserving an alert state. “Orienting” entails choosing and prioritizing key sensory information. As for the “executive control” process, it involves deciding what to focus on when the information available is at variance.
Scientists found that inflammation mainly had an impact on the alerting process, brain activity linked to staying vigilant. It did not seem to have any effects on the other two processes.
Mazaheri stated that the results showed clearly that inflammation affects a particular section of the brain network. This effect may bring about mental fog.
Professor Jane Raymond, another senior study author, said the research adds to the knowledge of the relationships between physical, mental and cognitive health. According to her, the finding suggests that “even the mildest of illnesses may reduce alertness.”
A better grasp of the links between inflammation and mental function can help for the development of treatments for some conditions.
“For example, further research might show that patients with conditions associated with chronic inflammation, such as obesity, kidney disease or Alzheimer’s, could benefit from taking anti-inflammatory drugs to help preserve or improve cognitive function,” said Dr. Leonie Balter, the first author of the study, which was aimed toward her PhD.
Slight changes in brain function may also serve as early signs of cognitive decline in people with inflammatory diseases, according to Balter.
The researchers plan to explore what effect inflammation on memory and other aspects of brain function in the future.