An analysis of cohort studies suggests that as many as one in eight people who have had Covid-19 may be diagnosed with a psychiatric or neurological condition for the first time within six months of testing positive for coronavirus. 

The analysis examines neurological and psychiatric outcomes in a total of 236,379 US patients using their electronic health records. The paper has not yet undergone peer review.  

As well as anxiety and mood disorders, the researchers looked at the incidence of conditions such as dementia, insomnia, encephalitis and Parkinsonism.

The findings indicate that 33.6 per cent of the patients received a diagnosis within six months of testing positive for Covid-19, with almost 13 per cent receiving having a diagnosis entered on their electronic records for the first time.  

Lead author Dr Max Taquet of Oxford’s psychiatry department, said the findings point to a higher incidence of psychiatric and neurological conditions in both hospitalised and non-hospitalised patients, which he described as surprising.

However, incidence tended to be higher in patients who needed hospital treatment, particularly for those who developed brain disorders.

Dr Taquet said: “For diagnoses like a stroke or an intracranial bleed, the risk does tend to decrease quite dramatically within six months … but for a few neurological and psychiatric diagnoses we don’t have the answer about when it’s going to stop.”

“Most diagnostic categories were commoner after COVID- 19 than after influenza or other respiratory infections, including stroke, intracranial haemorrhage, dementia, and psychotic disorders,” the paper says.

The authors say there is mounting evidence that Covid-19 survivors are at increased risk of mood and anxiety disorders as well as dementia in the first three months after they are infected, but that more robust longer-term data is needed to determine the scale of the impact.

The study does not prove that there is a causal link between coronavirus and these conditions, and may overestimate the rate of first diagnosis as a first entry of a diagnosis onto a patient’s electronic records may not always represent the first time they have received a diagnosis.