Clinical Manifestations

Neurological manifestations in individuals with Long COVID range from headaches to cognitive impairment and mental health issues. However, it remains unclear whether these individuals exhibit structural changes, functional changes, or both in the brain. In this study, we investigated the impact of Long COVID on mental health symptoms, cortical grey matter volume and thickness, and hippocampal volume in Brazilian individuals.

Individuals were divided into two groups based on Long COVID status: covid (symptoms of Long COVID) and control (No symptoms of Long COVID). Simultaneously, PHQ-9 and GAD-7 tests were applied on participants to evaluate severity of depression and generalized anxiety symptoms, respectively. Brain magnetic resonance imaging (MRI) of individuals presenting with Long COVID (n = 58) and of healthy control individuals (n = 21) were used for extracting volume and cortical thickness (CT) of regions of interest using FreeSurfer (v7.4.1). We performed an ANCOVA analysis and a linear regression to assess the difference between groups in PHQ-9, GAD-7, mean cortical thickness (CT), mean hippocampal volume, and total cortical grey matter volume. The data were corrected for age, sex, and years of formal education.

The Long Covid group presented significantly lower scores on PHQ-9 and GAD-7 than the control group (Beta = 6.20017 and 3.3105; p <0,001 and p <0,006, respectively). However, when comparing Long covid and control groups, we found no significant differences in the mean hippocampal volume (p = 0,831) and in the mean cortical grey matter volume (p = 0.193).

These preliminary data indicate significant changes in mental health among individuals with Long Covid; however, these changes do not correspond to observable alterations in brain volume as seen in MRI scans. This suggests that the pathophysiological changes associated with these symptoms are likely functional and metabolic in nature rather than structural and may not be detectable through imaging studies that primarily focus on brain anatomy, such as MRI.