A global study has been launched to investigate the potential long-term neurological effects of COVID-19.

The Alzheimer’s Association is initially funding the research that will be conducted in 30 countries and will follow the lives of 40,000 participants comparing cognitive function in those who had the virus to those who did not become infected. Both U.S and U.K. researchers are concerned that COVID-19 could damage the brain and central nervous system and lead to Alzheimer’s disease and other forms of dementia.

According to the Daily Mail, the first results won’t be presented until 2022 as scientists study how the virus causes cognitive decline in some patients. And it could be decades before full results are evaluated in the study subjects. However, current research in mouse models and examination of the brain tissue of deceased COVID-19 patients have provided cause for concern, say the researchers.

Dr. Sudha Seshadri, of the University of Texas, said that SARS-CoV-2, the pathogen responsible for COVID-19, attacks the hippocampus of the brain, the section responsible for memory and learning. The virus travels into the nose and up through the olfactory cells which are rich in ACE2 receptors, explains the lead author of the study. It then invades the brain by attaching itself to these ACE-2 receptors and then replicates itself causing the previously unexplained neurological symptoms some patients have experienced.

Researchers at Yale University discovered this unique ability by analyzing coronavirus infections in mouse models, brain cells in lab dishes, and brain tissue in deceased COVID-19 positive patients.

According to The National Interest, the pathogen also starves nearby brain cells of life-giving oxygen, causing them to wither and die. For some individuals, this can be deadly. According to The New York Times, half of the patients report neurological symptoms such as headaches, confusion, and delirium. Research published last July in Brain, a neurological journal, found preliminary clinical data that SARS-CoV-2 infection is associated with neurological and neuropsychiatric illness.

The current global study is also using data from other respiratory illnesses. For example, Dr. Gabriel de Erausquin, also from the University of Texas, says that “many of the flu-like illnesses have been associated with brain disorders,” according the Daily Mail. According to Harvard Health Publishing studies published in 2018 suggest that Alzheimer’s disease and other types of dementia may be triggered by viral infection of brain cells. One study revealed that people who develop shingles, which is caused by the herpes virus, have a higher risk of developing dementia later in life. The researchers noted one surprising finding. The people who were treated with antiviral drugs had a 90% reduce risk of getting dementia.

The researchers have outlined their plan under the guidance of the World Health Organization in The Journal of the Alzheimer's Association.