American Study Finds That Long COVID Linked to Lasting Brain Slowdown and Mental Fatigue
Nikhil Prasad Fact checked by:Thailand Medical News Team Aug 02, 2026 58 minutes ago
For many people, recovering from COVID-19 does not mean the illness is truly over. A new study has found that people living with long COVID are more likely to experience slower thinking, poorer decision-making abilities, persistent mental fatigue, and ongoing memory complaints compared to those who recovered from COVID-19 or never had the infection.
The research was conducted by scientists from the Department of Psychology at Fordham University, New York, and the Department of Psychology at the University of Wisconsin, Madison.
Researchers compared three different groups
The study involved 251 adults from across the United States. Participants were divided into three groups: 66 people who had never been infected with COVID-19, 123 who had recovered from COVID-19, and 62 who had been diagnosed with long COVID by a healthcare provider.
Participants completed a wide range of cognitive tests measuring memory, attention, reasoning, processing speed, and executive function, which refers to the brain's ability to plan, organize, focus attention, and solve problems. They also completed questionnaires about mental fatigue, perceived memory problems, depression, stress, and how much their symptoms affected daily life.
Long COVID affected both thinking speed and daily mental function
The researchers found that individuals with long COVID performed significantly worse on tests measuring processing speed and executive functioning. In practical terms, this means they needed more time to process information and had greater difficulty handling tasks that require planning, switching between activities, or concentrating.
Interestingly, memory tests such as short-term memory, working memory, word recall, and reasoning did not show major differences between the groups. Instead, the most consistent objective problems involved slower mental processing and reduced executive control.
People with long COVID also reported far higher levels of mental fatigue and subjective cognitive problems, often describing "brain fog," forgetfulness, and difficulty concentrating that interfered with everyday life.
This
Medical News report highlights that while laboratory testing detected measurable deficits in only certain brain functions, patients consistently reported much broader cognitive struggles affecting work, daily routines, and overall quality of life.
Depression and symptom burden made cognitive complaints worse
The investigators discovered that depressive symptoms were one of the strongest predictors of mental fatigue and self-reported cognitive difficulties among long COVID patients. Even after accounting for age, education, gender, and race, depression remained closely linked with how severely people felt their thinking abilities had declined.
The overall impact of long COVID symptoms on daily living also independently predicted mental fatigue. Those whose symptoms disrupted their quality of life the most were also the ones reporting the greatest mental exhaustion. Interestingly, stress and hopefulness were associated with mental fatigue initially, but these relationships became much weaker after the researchers adjusted for other important factors.
Some cognitive problems may persist for years
Among the long COVID participants, the average time since thei
r first COVID infection was approximately 2.3 years. Despite this lengthy period, cognitive complaints remained common.
The researchers found little evidence that simply allowing more time to pass after infection resulted in better cognitive function. In fact, people who had been infected for a longer period showed even slower performance on one processing speed test, suggesting that certain cognitive effects may persist for years in some individuals.
The study also found only weak connections between objective test results and people's own perception of their cognitive abilities. This suggests that medical professionals should not dismiss patient complaints simply because standard cognitive testing appears mostly normal.
Why these findings matter
The findings emphasize that long COVID is not solely a condition of lingering physical symptoms. Many patients continue experiencing genuine cognitive difficulties that affect their daily lives, even when standard testing identifies only subtle impairments. The results suggest healthcare providers should assess both objective cognitive performance and patients' personal experiences, while also paying close attention to depression and the overall burden of persistent symptoms. A more comprehensive approach may help identify those who need additional support and improve long-term care for people living with long COVID.
The study findings were published in the peer reviewed Journal of Intelligence.
https://www.mdpi.com/2079-3200/14/8/157
Read Also:
https://www.thailandmedical.news/articles/long-covid
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