Brain fog: What does it feel like and when does it happen?

06 February 2023 dot 6-minute read
Feature Mental health Feel Well Healthy Mind Brain fog
Brain fog is often temporary and can improve with time and rest. (Credit: Shutterstock)
Losing your train of thought, forgetting things and having trouble focusing or thinking. These are all characteristics of brain fog, a colloquial term used to describe symptoms that affect mental function.
Brain fog is not a medical condition. It is the body's response to health problems, from allergies to infectious diseases. Here are some of the most common conditions associated with brain fog:
Mental confusion can also be caused by medical conditions like chronic fatigue syndrome, autoimmune diseases like lupus or multiple sclerosis, cancer and post-COVID syndrome or long COVID

What causes brain fog in post-COVID syndrome

Brain fog gained attention after research showed many COVID-19 patients reported memory and attention issues similar to what cancer survivors call "chemo fog or brain fog".
Among cancer patients undergoing chemotherapy, radiation or surgery, brain fog shows up as a decline in mental sharpness, according to the American Cancer Society. On top of shorter attention spans and memory lapses, everyday tasks require additional mental effort, causing extreme fatigue.
Many COVID patients, even ones with mild cases, experience symptoms like chemo fog. Recent research points to neuroinflammation as the probable cause.
Using studies of mice with mild COVID-19 and post-mortem human brain tissue, the Stanford University School of Medicine discovered inflammation in the brain after COVID-19. The inflammation resembled damage sustained by a brain's white matter during cancer treatments.
The US National Institutes of Health (NIH), which supported the Stanford study, says COVID-related brain fog "could be caused by the immune system response" to the virus.
NIH explains, "The researchers found after a mild case of COVID-19, a type of human immune cell in the brain called microglia became activated and stayed more reactive even weeks later. When the microglia are more reactive, the brain has trouble keeping up with some of its regular tasks, such as making new neurons in the hippocampus, a region of the brain that plays an important role in learning and memory."
Cancer researchers have been testing drugs to improve the cognitive function of a chemo brain. If they turn out to be effective, these drugs may guide researchers on how to treat long COVID brain fog.

Long COVID brain fog symptoms

In post-COVID syndrome, you may experience headaches, sleep disturbances and fatigue apart from brain fog. (Credit: Shutterstock)
Researchers from the University of Oxford, whose study was published by the British Medical Journal (BMJ), interviewed 50 people who say their COVID fog disrupted their personal and work lives. They describe the following symptoms affecting their executive function, attention, memory and language. (The participants' quotes published in the study are condensed.)

Difficulty in planning, decision-making and working memory

One subject describes how grocery shopping causes sensory information overload. "One of the things I have realised is how many things I do in my normal day that are cognitive. At a supermarket, the planning, getting there, choosing stuff, all of that is actually really difficult."

Difficulty sustaining and dividing attention and processing speed

A doctor shared she lost her ability to multitask. "I can't cope with multiple inputs. I've got to focus on just one thing, or I make massive mistakes and it's like I forget my intentions all the time."

Difficulty with long-term memory

A participant could not recall if he asked a person the same question twice in two minutes. "I can't remember significant things that have happened in the past either."

Difficulty with words, fluency, reading comprehension and writing

One participant found it challenging to "comprehend and take in written information". "I had a form sent to me at work, and I just felt, 'I can't do this at the moment and put it to one side and hoped to come back to it because it's just been too difficult."
The impact of brain fog found several participants in the Oxford study unable to work, or if they did, they adopted reduced hours. Those in demanding roles experienced a loss of self-worth and self-doubt, worsened by anxious thoughts of making mistakes.

When to seek help

A Stanford Health Care study showed COVID-19 patients experienced slower information processing for at least two months. (Credit: Shutterstock)
Many medical conditions can cause brain fog. Talk to your doctor if you experience persistent problems with your ability to:
  • think and reason
  • concentrate
  • remember things
  • process information
  • learn, speak and understand
List down your symptoms and how long you've had them and share them with your physician to get a proper diagnosis.
Healthcare providers suggest the following activities for brain health.
  • Take mental breaks if you have difficulty dealing with large amounts of information.
  • Break down complicated tasks and schedule them when you're most productive.
  • Stay active to help improve concentration and ability to learn.
  • Practise meditative or yoga breathing techniques to help you relax when you're confused or anxious.
  • Nourish your brain with a healthy diet filled with vegetables, fruits and nuts.
  • Practice good sleep hygiene to boost your immunity.
  • Maintain a support network of family and friends with whom you can check in during stressful times.
Brain fog can develop or persist for three months or more in long COVID, based on an analysis of 19 studies covering 11,324 COVID patients.
At least two COVID patients in the Oxford study experienced brain fog for seven to eight months after their illness. About 13 of the study's respondents reported experiencing less brain fog four to six months after their initial interview, although they still needed more rest and sleep.
The focus group in the Oxford study shared their apprehensions about the future of their professional lives. Some whose brain fog has improved still call in frequent sick days at work. "For me, it's been going from working at 110 per cent pace to being unable to get out of bed," one respondent shares.
Doctors were not overly worried about brain fog until COVID, which has affected more than 620 million people based on WHO's November 2022 data. Studies show cognitive impairment associated with the virus can affect people's quality of life and their ability to earn a living. Financial stress can lead to mental health problems and raise the risk of chronic diseases.
Reduce financial stress and future worries of debilitating brain fog. Invest in a critical illness plan that provides medical support and covers health risks for stroke, cancer, dementia and more. Getting ahead of a problem can help ease a mind worried about the future.
The effect of one night of sleep deprivation on your overall wellbeing is significant. In this episode of AIA Voices, sleep and mental health experts Olivia Arezzolo, Kate Yan and Asher Low explain what happens when we get less than adequate sleep.
AIA Voices is a community of influential and educational voices from around Asia to talk about life, health and wellness. A platform to educate, motivate and inspire people to make positive behavioural changes on their health and wellness journey. Providing an opportunity for communities across Asia to connect, collaborate, and learn from each other. Designed to drive AIA One Billion, our ambition to engage a billion people to live Healthier, Longer, Better Lives by 2030.
Stanford Medicine. 2022. Brain fog after COVID-19 has similarities to 'chemo brain,' Stanford-led study finds. [online] [Accessed on 18 October 2022]
National Institutes of Health COVID-19 Research. 2022. A Possible Mechanism Behind Brain Fog. [online] [Accessed on 18 October 2022]
Journal of the Neurological Sciences. 2022. Mid and long-term neurological and neuropsychiatric manifestations of post-COVID-19 syndrome: A meta-analysis [online] [Accessed on 18 October 2022]
Brain, Behavior, Immunity. 2022. Fatigue and cognitive impairment in Post-COVID-19 Syndrome: A systematic review and meta-analysis [online] [Accessed on 18 October 2022]
Cleveland Clinic. 2022. Strategies for Busting Up Brain Fog. [online] [Accessed on 18 October 2022]
Journal of Psychosocial Nursing and Mental Health Services. 2021. Brain Fog: A Bit of Clarity Regarding Etiology, Prognosis, and Treatment. [online] [Accessed on 18 October 2022]
American Cancer Society. 2020. Chemo brain. [online] [Accessed on 18 October 2022]

This is general information only and is not intended as financial, medical, health, nutritional or other advice. You should obtain professional advice from a financial adviser, or medical or health practitioner in relation to your own personal circumstances.

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