The research on the short and long-term effects of COVID-19 disease is ongoing. Still, scientists have found severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects the brain causing loss of smell and taste, dizziness, muscle pain, fatigue, and other cognitive impairments. However, it remained unknown why certain people developed neurological symptoms while others did not.
Kameshwar Prasad of the Rajendra Institute of Medical Sciences in India and an international team of researchers conducted the most extensive systemic review and meta-analysis of past COVID-19 cases involving any type of neurological complications.
The authors write:
“Our review shows that pre-existing neurological conditions are a common comorbidity associated with COVID-19. After hypertension and diabetes, the combined comorbidity of cardiovascular/cerebrovascular disease was the third most commonly reported comorbidity associated with COVID-19.”
They found one-third of patients with COVID-19 infection experienced at least one neurological manifestation. One in fifty patients had a stroke. Age also plays a risk with people over the age of 60 developing neurological symptoms associated with increased mortality.
The team hopes that their findings could help with clinical practice and future research in understanding the severity and mortality of COVID-19 infection. It could potentially help clinicians with treating neurological manifestations during infections and those that persist in long COVID.
The study “Frequency of neurological manifestations in COVID-19: a systematic review and meta-analysis of 350 studies” is available as a preprint on the medRxiv* server, while the article undergoes peer review.
Collecting data
The team conducted a literature search reviewing COVID-19 cases from December 31, 2019, to December 15, 2020. Studies were included in the review if they featured patients positively diagnosed with COVID-19 and presented with one or more neurological symptoms temporarily associated with infection. The neurological symptoms had to have not been explained by an alternative health reason. The team also included cases that could have potentially been cases of SARS-CoV-2 infection, but there was a lack of diagnostic testing.
The meta-analysis included 350 studies from 55 countries. A total of 20 studies including patients with COVID-19 younger than 18 years old and 14 studies only included patients over the age of 60.
There were 145,634 patients with SARS-CoV-2 infection included in the analysis. About 54% of patients were male, and 89% of patients required hospitalization. Some patients with neurological symptoms had pre-existing conditions, with the highest being hypertension at 26%, followed by diabetes at 14%.
Prevalence of neurological manifestations during infection
The most common neurological symptoms included fatigue (32%), muscle pain (20%), muscle pain or fatigue (31%), dizziness (7%), loss of smell (19%), loss of taste (21%), and headache (13%).
About 11% of patients experienced brief episodes of confusion/delirium, 7% had impaired consciousness, and 45% had agitation.
In 33 studies, there were about 17 different neurological diagnoses in patients with COVID-19, indicating a broad spectrum of neurological manifestations.
Of these, 2% of patients experienced a stroke.
The researchers also found a 24% prevalence for neuropsychiatric disorders and a 5% risk for muscle injury.
Specific neurological factors may be linked to severity of disease
Patients with severe COVID-19 disease were associated with skeletal muscle injury or damage, impaired consciousness, and fatigue.
However, patients with severe COVID-19 infection were less likely than patients with mild infection to have changes in smell or taste.
Results showed that about half of patients who did not require hospitalization had a loss of smell, with 44% reporting loss of taste. Other common symptoms included headaches and muscle pain.
Age differences in neurological manifestations during infection
The team’s systemic review included 3,1,76 older patients with a range of ten different neurological symptoms. Older adults were more likely to experience acute confusion or delirium, fatigue, muscle pain, dizziness, and headache.
Adolescent patients with SARS-CoV-2 infection were more likely to report fatigue or muscle pain, loss of smell or taste, headache, fatigue, and seizure.
About 27% of patients with COVID-19 disease and neurological symptoms died. People over the age of 60 were significantly linked to an increased risk of dying from the disease.
*Important Notice
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.