Many seniors have cognitive decline one year after a bout with severe SARS-CoV-2 infection, according to the results of a new study from China. Measures are needed to address this public health challenge, investigators say.

The researchers performed a cohort study of 1,438 COVID-19 survivors who were not cognitively impaired prior to infection and did not have family histories of dementia. Participants were 60 years and older and had been discharged from hospitals designated for treating COVID-19 patients in Wuhan, China. Their cognition was tested at 6 and 12 months after discharge.

One year after discharge, 9% of those who had survived severe disease had dementia and 26% had mild cognitive impairment, higher proportions than their uninfected peers, reported Yan-Jiang Wang, M.D., Ph.D., of Third Military Medical University, Chongqing, China. 

“The incidence of dementia or MCI was not different between individuals with nonsevere cases and uninfected control individuals,” they noted. More than 3% of COVID-19 survivors overall had dementia and 9% had mild cognitive impairment one year after hospital discharge.

The patients’ long-term cognitive function was classified into different levels, either stable cognition or early-, late- or progressive cognitive decline. Severe COVID-19 was associated with a higher risk of all types of cognitive decline, Nonsevere COVID-19, meanwhile, was linked to a higher risk of early-onset cognitive decline. Results were adjusted for well-recognized contributors to dementia, including age, sex, education level, body mass index and comorbidities.

A pattern in respiratory disease

The results support earlier findings of long-term cognitive and neurological complications in severe respiratory diseases, the authors said. In addition, there is evidence of a similar trend among survivors of past pandemics. One study, for example, found that 15% of patients with severe acute respiratory syndrome (SARS) experience long-term problems with memory and attention post-infection, the researchers noted. 

“It is worth noting that 21% of individuals with severe cases in this cohort experienced progressive cognitive decline,” suggesting that COVID-19 may cause long-lasting damage, Wang and colleagues wrote. “These findings imply that the pandemic may substantially contribute to the world dementia burden in the future,” they concluded.

The study was published in JAMA Neurology.