In a recently published article in Neuropsychology, scientists have described demographic and clinical predictors of cognitive dysfunction and self-perceived cognitive difficulties in coronavirus disease 2019 (COVID-19) survivors one-year after infection.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative pathogen of COVID-19, has caused massive damage to the healthcare and economic sectors worldwide. Although the virus causes asymptomatic or mildly symptomatic infection in most affected individuals, long-term clinical consequences have been observed in a considerable proportion of COVID-19 patients, even six months after recovery.
The long-term manifestation of COVID-19 is medically termed “long COVID.” The most common symptoms of long COVID include cognitive impairments and mental health disorders.
In the current study, scientists have determined both objective cognitive deficits and self-perceived (subjective) cognitive difficulties in COVID-19 survivors one-year post-infection. They analyzed the data to identify demographic and clinical predictors of cognitive dysfunctions and complaints.
A total of 110 adults who had laboratory-confirmed SARS-CoV-2 infection 12 months before were enrolled in the study. The participants were subjected to neuropsychological evaluation, including a brief visuospatial memory test, California verbal learning test, and symbol digit modalities test.
These cognitive tests have been designed to assess processing speed, visual learning/memory, and verbal learning/memory functions. A test score of less than 38 was considered abnormal performance. More than two abnormal test results were considered cognitive dysfunction.
The participants were also asked to complete a set of questionnaires to assess self-perceived cognitive difficulties (cognitive complaints). These questionnaires were designed to collect self-reported information on perception, memory, motor function, anxiety, depression, fatigue, and overall quality of life.
The study participants were recruited consecutively for one-year post-infection. The age of participants ranged from 19 years to 73 years. The most commonly reported comorbidities were hypertension, diabetes, and previous neurological diseases (migraine, epilepsy, and transient ischemic attack).
During the acute infection phase, the most commonly reported symptoms were myalgia, hyposmia/anosmia, hypogeusia/dysgeusia, fever, headache, and sleep disturbance.
Objective cognitive performance
The cognitive performance test results indicated that the study population has significantly lower scores in all three tests compared to the standard general population.
Considering all test results collectively, a better cognitive performance was noticed in participants with higher educational backgrounds. In contrast, previous neurological diseases and the presence of headache and sleep disturbance during acute infection phase were associated with lower cognitive ability.
Considering a test score lower than 38 as the cutoff for abnormal performance, the findings revealed that about 52% of participants have abnormal test performance in at least one of the three cognitive tests. About 18% of participants exhibited abnormal performance in two or more cognitive tests.
A significant association was observed between abnormal performance in two or more cognitive tests and educational background, previous neurological condition (headache or migraine), and COVID-related sleep disturbance.
Subjective cognitive difficulties
A total of 108 participants completed the questionnaire assessing self-perceived cognitive difficulties. A score of 43 or more was indicative of cognitive complaints. Significantly higher cognitive complaints were observed among female participants, older participants, and those with COVID-related headaches and sleep disturbances.
The degree of cognitive complaints showed a significant association with higher levels of anxiety and depression, fatigue, and poor mental and physical quality of life. A lower educational background, female gender, and headache during acute infection were identified as significant predictors of cognitive complaints.
The study highlights long-term cognitive difficulties in a subset of COVID-19 survivors. About 52% of study participants have abnormal performance in at least one of the three cognitive tests performed. Furthermore, about 33% of participants have cognitive complaints.
Based on the study findings, a lower educational background and acute infection-related headache and sleep disturbance are crucial predictors of objective cognitive dysfunction one-year post-infection.