Studies find COVID linked to increased risk of dementia and brain fog

The SARS-CoV-2 (COVID-19) pandemic has led to a host of health concerns, from respiratory damage to increased fatigue. But research has also emerged that contracting COVID could increase a person’s risk of neurological and psychiatric conditions – particularly in adults.

A study by Maxime Taquet et al in The Lancet Psychiatry [1] sought to analyse and understand the neurological and psychiatric risks after COVID-19 infection. And they discovered that even 2 years post-infection, patients were at a higher risk of neurological conditions versus other respiratory infections.

Let’s break down the research and its findings, and what that means for people who catch COVID-19.

COVID and cognitive risks: a study

The study is titled “Neurological and psychiatric risk trajectories after SARS-CoV-2 infection: an analysis of 2-year retrospective cohort studies including 1 284 437 patients”, by Maxime Taquet et al [2] It was published in The Lancet Psychiatry in August of 2022.

Its aim was to analyse the association between COVID-19 and “increased risks of neurological and psychiatric sequelae” post-infection. It looked at 2-year retrospective studies, with data taken from the TriNetX electronic health records network. 

In particular, it isolated a group of patients of varying ages, who contracted COVID-19 between 20 January 2020 and 13 April 2022. They then compared these patients’ neurological risks to a peer group of patients who had contracted other respiratory infections, to see whether that risk was indeed higher.

Researchers stratified patients by age: less than 18 (children), 18–64 (adults), and over 65 (elderly). They then assessed the risks of 14 different neurological and psychiatric diagnoses following COVID infection – including brain fog (termed “cognitive deficit” in the study) and dementia.

It looked at 2-year retrospective studies, with data taken from the TriNetX electronic health records network. 

In total, the study identified and followed 1,284,437 patients as matched with an equal number of patients who contracted a different respiratory infection. It found that risk factors for common psychiatric disorders such as mood disorders or anxiety decreased after about 1–2 months. On the other hand, risks of brain fog, dementia, psychotic disorders, and epilepsy remained high even after 2 years.

For children, they had a notable increased risk for brain fog, insomnia, and epilepsy. But brain fog had a finite risk horizon of little over 2 months.

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On the other hand, seniors (those aged 65 and older) faced an increased risk of mortality following a neurological or psychiatric diagnosis – especially dementia or epilepsy. 

As for COVID variants, risk factors were similar both before and after the alpha and omicron variants. However, the delta variant showed increased risk after its emergence, alongside a higher mortality rate. 

This means that relative to other respiratory infections, COVID-19 showed only a transient increase in the risk of mood and anxiety disorders. But there is a significant increase in the risk of psychotic disorders, brain fog, dementia, and epilepsy – which persists even over 2 years. Adults, and particularly the elderly, are at an even higher risk versus children.

What is brain fog?

Cognitive deficit, or brain fog, is not necessarily an official clinical diagnosis. Rather, it is a term people use to describe a condition in which their thinking is sluggish and slow, or when they feel “spaced out”.

A person can experience brain fog due to varying circumstances, such as sleep deprivation, illness, or concussion. Some symptoms of brain fog include [3]:

  • Forgetfulness and other memory issues
  • Unclear thinking
  • Difficulty concentrating
  • Headaches
  • Distractedness and poor concentration

People who experience brain fog will find it usually resolves itself once they’ve returned to a healthy routine, especially for brain fog caused by poor sleep or stress. But for brain fog caused by illness, it may persist even for weeks or months despite other symptoms disappearing.

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What is dementia?

Much like brain fog, dementia is not a clinical disease but rather a term used to describe the condition of impaired memory and thinking. Alzheimer’s is a form of dementia, for example. 

Dementia often affects elderly people, but it is not normal forgetfulness or difficulty thinking. Persons suffering from dementia may find that they cannot recall words for familiar objects, get lost in familiar neighbourhoods, or cannot complete an action by themselves.

The condition affects certain cognitive functions, including:

  • Memory
  • Attention
  • Communication
  • Critical thinking
  • Visual perception

Some factors that increase the risk of dementia include age (over 65 years old), family history, ethnicity, and heart conditions. [4]

COVID and neurological conditions

There are several ways that COVID-19 can affect a person’s brain and cognitive functions. [5] One direct way is via encephalitis, which is when an infection causes an inflammation of active brain tissues. Encephalitis has a 10% risk of mortality in patients, especially in severe cases. [6]

COVID patients over the age of 70 are also at significant risk of suffering a stroke – but even young adults carry an increased risk of a stroke versus the risk from your usual flu. [7]

Another potential way COVID affects your brain is by oxygen deprivation. [8] As COVID causes respiratory distress, this can lessen the amount of oxygen that enters the bloodstream – and eventually, lead to a lack of oxygen in the brain.

Finally, individuals who contract COVID may develop cells called megakaryocytes in their brains. These cells create platelets, and should not be found in the brain area. There could be a link between the presence of megakaryocytes and neurological damage from COVID. [9]

Managing cognitive and neurological conditions post-COVID

There are several ways to manage cognitive dysfunctions in the wake of a COVID-19 infection. Gradually reintroducing light physical activity – especially aerobic exercise, such as a walk – is beneficial, but remember to start small and slow. Adjusting your diet may help as well.

Sleep is essential to recovery, so ensure you get enough rest in good sleeping conditions. This allows your body to recharge and heal. When you’re awake, social activities can aid your thinking and memory, as well as boost your mood and overall well-being. And as always, consult your doctor regarding potential treatments. [10]

This study highlights the need for further research into the cognitive effects of COVID-19, so that doctors and scientists can better understand the link and the conditions that emerge post-infection. But in the meantime, there are ways to manage and treat symptoms to minimise the impact these cognitive dysfunctions have on your life – and begin recovery towards a healthy state.

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