Shining a Light on Brain Fog

If anything positive is to come out of the pandemic it is that the spotlight is now on brain fog. Little attention has been paid to the patients with a wide variety of medical conditions who have experienced the debilitating nature of brain fog in the years preceding the pandemic. Brain fog, like many of the autoimmune and neurological conditions associated with it disproportionately affects women, and, as a result, historically has been downplayed by clinicians who have tended to focus on the physiological rather than the cognitive aspects of their conditions. In the wake of the pandemic, it has become more difficult to dismiss brain fog as it emerges as the most commonly reported and most debilitating lingering symptom post-COVID infection.

What is Brain Fog?

Brain fog is not a medical condition, rather it is a general term used to describe a collection of symptoms affecting memory, attention, learning, executive functions (planning, organization, making decisions, assessing risk, inhibiting behavior, etc.) language, processing speed, spatial navigation (clumsiness) as well as loss of mental clarity and mental fatigue.


People with brain fog often describe these symptoms:
  • “I just can’t think straight.”

  • “I’m too tired to think.” “I can’t concentrate.”
  • “I struggle to recall what I did yesterday.”
  • “I keep having to reread the same sentence.”
  • “I can’t work because I can’t ‘tune out’ other people’s conversations.”
  • “My thinking is sluggish.”
  • “My life is like a game of Charades, I can’t find the right word, or I say the wrong word.”
  • “My language isn’t as fluid or as rich as it ordinarily would be.”
  • “I’ve lost my sense of humor.”
  • “I’m struggling with small decisions like what to wear or what to have for dinner.”
  • “I keep bumping into things, spilling things, or slamming doors.”

Most people will have experienced some, if not all, of these symptoms at some point in their lives. In fact, it is common to have these issues when sick with the flu or other illness, if a person has jetlag, has been awake too long, has disrupted sleep, works long hours or is in a stressful situation.

Brain fog is different from these short-term disruptions. With brain fog symptoms are persistent, occur regularly and interfere with quality of life, relationships and work. Brain fog can be extremely debilitating and disconcerting. For example, a quick-witted person, always first with a witty retort, finds that with brain fog it takes them longer to process what someone says, make sense of it and formulate a response. By the time they come up with a one-liner the moment has passed. Because their sharp wit is so intertwined with who they are their brain fog symptoms make them feel like they have lost themselves. Their family and friends notice the change and may interpret their lack of humor as a “coolness” toward them. When it comes to memory issues it’s not difficult to see how being forgetful could cause issues with jobs and even relationships. Every symptom can have life-altering consequences.

What Causes Brain Fog?

Brain fog needs to be taken seriously; however, it is not a disease, disorder or diagnosis, rather it is a warning sign that something is amiss. A signal to take action. Much like a persistent cough needs to be checked out to find the underlying cause. The relationship between COVID-19 and brain fog is not yet fully understood, but it is likely a complex interplay between inflammation, immune and metabolic changes, depression, oxidative stress and PTSD.

‘I keep bumping into things, spilling things, or slamming doors.’

It is possible that an immune response that was protective in the acute phase of the infection has become overreactive, triggering ongoing inflammation and dysregulating brain cells, interfering with their ability to communicate. It is also possible that damage to the circulatory system makes it more difficult for the brain to pick up the nutrients it needs to function well. And it is likely that many other non-COVID factors known to contribute to brain fog also play a role. Many of these factors that contribute to or exacerbate symptoms are modifiable. Identifying, changing, or treating these factors could dramatically minimize brain fog symptoms.

Factors that contribute to brain fog include:
  • Underlying health condition
    o auto-immune conditions (e.g., lupus, Sjogren’s), inflammatory diseases, neurological conditions (e.g., migraine, multiple sclerosis)
    chronic pain (e.g., fibromyalgia), other chronic conditions, depression, anxiety, type 2 diabetes, and some cancers
  • Side-effect of medication
    o chemotherapy, medications for auto-immune diseases, and depression, antihistamines, anti-nausea tablets, pain medications
  • Hormonal imbalance or fluctuations
    o PMS, pregnancy, menopause, thyroid dysfunction, etc.
  • Nutritional or dietary deficiency
    o vitamin B-12, iron, folate or Omega-3 deficiency
  • Lifestyle factors
    o poor sleep, poorly-managed chronic stress, lack of exercise, lack of mental stimulation

What Can Be Done?

It is important to speak to a doctor to rule out or treat any underlying health condition or hormonal imbalance that could be contributing to brain fog.

Any prescribed medication that acts on the central nervous system has the capacity to impair cognition. Medications should never be stopped without speaking to the prescribing doctor, but possible alternatives should be discussed. Read medication leaflets for potential side-effects.

Prioritize Sleep

Keep to a regular routine. Go to bed and get up at the same time each day. Manage exposure to light. Open curtains on waking, spend at least an hour a day out in natural daylight, dim lights from 8 p.m., turn off devices emitting blue light an hour before bed. Brush teeth an hour before bed to avoid bright light just before sleep. Sleep in a darkened room. Charge devices in another room and turn notifications off. To enter sleep core body temperature needs to drop by 1 degree Celsius—think cool rather than warm bedroom. A hot bath before bed can help lower core body temperature.

Manage Stress

Smile more, laugh more, have fun. Set aside time each day to do a beloved activity. Being fully present in the moment doing something that fully engages attention, can distract from pain, other ongoing symptoms or worries. Create a go-to laughter stash (videos, memes, podcasts, etc.) for managing stress. Open said stash before stress takes hold and have a laugh. Laughter is nature’s natural stress buster, it lowers cortisol levels.


Exercise both body and brain. When recovering from COVID it is important to take things slowly and avoid the boom-and-bust cycle. Taking baby steps to gradually rebuild condition both physically and mentally is key.


Food is the fuel the brain needs to function properly. Nourish it. Rubbish in rubbish out. Everyone, not just those affected by brain fog, need to shop for their brains. Think of an overall diet rather than individual ingredients. A Mediterranean diet is best for brain health. Following a Mediterranean diet should negate the need to purchase supplements—there is currently no evidence to support their effectiveness for memory function or to stave off brain fog or dementia. If a medical doctor diagnoses a B-12 deficiency, folate deficiency or iron deficiency, they will prescribe accordingly.

General Survival Strategies

Focus on what a person can do, not what they can’t. Have a stash of easy “no brain” stuff to do for when brain fog strikes. This allows a person to feel productive even on bad days.

Step back and breathe. Feeling overwhelmed can elicit the stress response, which may further impair cognitive abilities. The brain will benefit from the extra oxygen. Once calm again break the task down into small achievable steps.

Seek support. With a broken ankle or arm there would be no issue asking people for help with certain tasks. Why should it be any different with brain fog? The brain is just another part of the body. Reach out and ask for support from family, friends and colleagues.


Brain Fog Is Not Dementia

As we get older, experiencing problems with memory can set “am I getting dementia?” alarm bells ringing. In particular women going through perimenopause and menopause are often unaware that hormonal changes can give rise to brain fog. They catastrophize that they are getting dementia. So, I want to make it very clear that the memory issues associated with dementia are characteristically different from those experienced with brain fog. However, if you regularly experience any of the following, it is worth chatting with your doctor:

  • Disorientation about where you are, or what time of day it is.

  • Becoming lost in a place you’ve been familiar with for years.
  • Repeating the same story without realizing it.

When a person is concerned about memory it is always best to err on the side of caution, and arrange a visit to the doctor. Stress can impair memory function so worrying about memory can make memory worse.

The good news is that adopting a brain healthy lifestyle not only reduces the risk of developing dementia, but it can also change the trajectory of the disease, delaying symptoms in those who already have the pathology in their brain.

Sabina Brennan, PhD, is a health psychologist, neuroscientist, host of the Super Brain podcast and author of two Irish Times No. 1 bestsellers, Beating Brain Fog and 100 Days to a Younger Brain.