Small fMRI study finds cognitive and sleep differences five years after COVID-19

Researchers assessed 14 people who had been hospitalized with COVID-19 at one, two and five years after recovery. The single-center study compared their resting-state fMRI and neuropsychological results with those of 20 healthy controls. Imaging measures included amplitude of low-frequency fluctuations (ALFF), regional homogeneity (ReHo) and small-worldness.

At five years, survivors had higher Pittsburgh Sleep Quality Index scores and lower Logical Memory and backward Digit Span scores than controls. They also showed increased ALFF in the right supramarginal gyrus, decreased ALFF in the right precuneus and decreased ReHo in the left middle frontal gyrus. These imaging differences were associated with poorer cognitive performance and sleep. Over follow-up, sleep scores improved from year one to year two, while small-worldness decreased at year two and increased by year five; the year-five measure was negatively correlated with backward Digit Span scores.

The findings suggest that cognitive, sleep and brain-function differences may persist in some survivors, but the small sample and single-center design limit generalizability. The study reports associations and does not establish that the imaging changes cause symptoms or indicate how they should be managed clinically.