According to a new US study, cognitive impairment - described as brain fog -can persist for months in COVID-19 patients, even for some who were not hospitalised.
The research, published on Friday in the journal JAMA Network Open, found that almost a quarter of COVID-19 patients in a Mount Sinai Health System registry experienced some issues with their memory.
Although hospitalised patients were more likely to have such brain fog after a coronavirus infection, some outpatients had cognitive impairment too.
One of the researchers found that impairments in executive functioning, processing speed, category fluency, memory encoding, and recall were predominant among hospitalised patients.
The US Centers for Disease Control and Prevention includes brain fog, or what it describes as difficulty thinking or concentrating, on its list of post-COVID conditions.
The new study included data from April 2020 through May this year, on 740 COVID-19 patients with no history of dementia.
The average age of patients was 49.
Cognitive functioning was assessed for each patient and the researchers analysed the frequency of cognitive impairment among the patients.
Among all the patients, the researchers found that 15% showed deficits in fluency in their speaking; 18% showed deficits in their cognitive processing speed; 20% in their ability to process categories or lists; 23% in memory recall and 24% in memory encoding, among other impairments.
The researchers noted that hospitalised patients were more likely to have impairments in attention, executive functioning, category fluency and memory.