One of the reasons behind the successive Covid-19 lockdowns was to reduce the risk of the disease spreading to the elderly and the vulnerable. Those who were already frail or had weakened immune systems were known to be at a higher risk not only of catching Covid but also of developing a more severe form of the disease.
That was as true of those with Alzheimer’s and other forms of dementia as it was for other life limiting conditions.
According to the Alzheimer’s society, studies show that of the 73,766 people who died from COVID-19 in 2020 in the UK, nearly 25% were suffering from dementia.[1]
Various reasons were put forward for this high death rate including the fact that many dementia patients were living in care homes, required close care, and may have also been suffering from other underlying conditions. The impact on health due to isolation from family and loved ones was also identified as a possible cause.
So we know that Alzheimer’s can increase the risk of severe Covid. Now researchers are starting to show that the reverse could also be true.
One American study, which looked at over six million adults aged over 65, revealed that those who had contracted Covid-19 had a significantly higher risk of developing Alzheimer’s within the following 360 days than non-Covid sufferers.
This risk was especially high in women and in those aged over 85.[2]
These conclusions were echoed by a Danish study which found increased risks not only between Covid and Alzheimer’s but also between Covid and Parkinson’s and ischaemic strokes.[3] Interestingly this study concluded that the risks for contracting Alzheimer’s following a covid infection were on par with the already known risk of contracting Alzheimer’s following a bout of flu.
One potential conclusion put forward by the Danish researchers is that those who are in such an early stage of Alzheimer’s that the disease has not yet been identified my still be at greater risk of catching Covid. This potentially bi-directional relationship was also considered by the American researchers who commented that it was still unclear “whether COVID-19 might trigger new-onset Alzheimer’s disease or accelerate its emergence.” Another study echoed this potentially circular relationship, commenting that in common with other infections Covid-19 has been seen to increase the risk of cognitive impairment.[4]
Either way, the findings of these studies and others are of sufficient concern for further research to be called for in this area. Understanding whether Covid causes or accelerates Alzheimer’s, or whether Alzheimer’s even in its early stages makes individuals more susceptible to contracting Covid and similar infections, could help to progress our knowledge of a life-limiting condition which can have such a devastating impact on sufferers and their loved ones.