People with concussions often report a brief period of amnesia or forgetfulness, where they cannot remember what happened immediately before or after the injury. This study did not specifically exclude people with degenerative brain conditions such as Alzheimer’s or Parkinson’s diseases, but the scientists do not think these would explain the changes they found.A concussion can affect memory, judgment, reflexes, speech, balance and muscle coordination. The scientists also found slightly reduced scores for brain functions of thinking and remembering in the group that went on to have COVID. However, these were in different brain areas to those affected after COVID. There were some differences between the groups before COVID, with smaller volumes of areas deep within the brain. Another study is needed to determine whether the same brain alterations would occur in younger people, or whether these findings are common only to older people. The brain changes found in this study were more pronounced in the older participants, so it could be that older people are more susceptible. This study also only included people aged 51–81, so we do not know whether these findings are relevant for younger people or children. More research over a long time would help us understand the trajectory of brain changes. This includes whether these brain changes will get worse over time, or whether they will go back to normal or previous levels of function. There are several important things we still do not know. So does this study prove all people who have had mild COVID infections will have these same brain changes and long-term brain degeneration? Not necessarily.
Isolated, confused and depressed: the pandemic's toll on people with dementia and their carers However, the authors suggest this could be due to inflammation, degeneration which spreads through the brain pathways associated with smell, or sensory deprivation due to loss of smell. The study did not look at the mechanisms of mild COVID in the brain. These changes could explain the reported symptoms of long COVID, such as brain fog. Problems with memory and attention are also frequent for people with these diseases and disorders, indicating mild COVID infection may accelerate brain degeneration. They did not see the same changes, confirming they are related to COVID.ĭecreases in brain volume are common to many brain diseases and disorders associated with degeneration, and have been found in people with mild cognitive impairment, Alzheimer’s disease, depression and traumatic brain injury, among others. To show these changes were specific to COVID and not just related to having a respiratory illness, the scientists also looked at a group of people who had pneumonia. How does COVID affect the brain? Two neuroscientists explain
They performed worse in a test for attention and mental flexibility, a finding that was associated with volume reductions within a part of the cerebellum related to smell and social relationships.įurther research is needed to see if COVID affects the brains of younger people in the same way. The post-COVID group also showed a reduction in overall brain size between their MRI scans that wasn’t seen in the non-COVID group, and had altered connections between different brain regions in the olfactory cortex, an area related to smell. Affected brain regions included the parahippocampal gyrus (an area related to memory) and the orbitofrontal cortex, which is located at the front of the brain and is important for smell and taste. This is equivalent to between one and six years of normal brain ageing. The group who had mild COVID an average of five months beforehand had thinning of brain tissue in several brain regions, ranging from 0.2% to around 2% compared to their pre-COVID scan. This allowed the scientists to determine the specific effects of mild COVID infection on brain structure and function. They then compared this to the same data collected three years later, when about half of those participants had mild COVID infection, and the other half had not caught COVID. They looked at brain magnetic resonance imaging (MRI) scans and tests of brain function in 785 volunteers who were assessed before the pandemic. Scientists collected data as part of the massive UK Biobank database.
Long COVID is very common, and may affect more than half of the people who catch COVID, even if they have a mild case.
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