Brain fog, 2026, Bojnowska & Debowska

Dolphin

Dolphin

Senior Member (Voting Rights)
13: Brain fog
Urszula Bojnowska
and
Agata Debowska
in Elgar Encyclopedia of Personality and Individual Differences


Category: ChapterPublished: 22 Oct 2026Page Range: 56–58
Collection: Psychology 2026DOI: https://doi.org/10.4337/9781035349173.00018Publisher: Edward Elgar Publishing
Keywords: Brain fog; Cognitive dysfunction; Brain fog scale; BFS; Standardized assessment; Long COVID


This chapter explores the phenomenon of brain fog, a subjective experience of cognitive dysfunction characterized by forgetfulness, mental fatigue, and confusion. Frequently associated with conditions such as Chronic Fatigue Syndrome, Postural Tachycardia Syndrome, and long COVID, brain fog significantly diminishes patients’ quality of life by impairing daily functioning, academic performance, and productivity.

Historically, research on brain fog has been hindered by a lack of standardized clinical definitions and inconsistent measurement approaches.

To address this gap, recent advancements have led to the development of the Brain Fog Scale (BFS).

The BFS is a validated, 23-item self-report tool that quantifies brain fog across three dimensions: mental fatigue, impaired cognitive acuity, and confusion.

By providing a structured and reliable assessment method, the BFS aims to unify clinical evaluation and facilitate future research into this pervasive cognitive impairment.
 
Brain Fog Scale (BFS)

Mental fatigue
1. My thinking has been slow
2. I have felt mentally exhausted
3. I have felt fatigued
4. I have been easily distracted
5. I have found myself getting annoyed
6. I have felt sleepy

Impaired cognitive acuity
7. I have found it difficult to remember and understand new information
8. I have found myself forgetting certain words, such as the names of objects
9. I have found it difficult to think logically
10. I have found it difficult to concentrate
11. I couldn’t think clearly
12. I have had a hard time finding the right words
13. I have found it difficult to organise my thoughts
14. I have felt like my mind’s gone blank
15. I have found it difficult to understand words when reading

Confusion
16. I have had a hard time understanding what others say
17. I have been daydreaming
18. I have felt spacey
19. I have felt confused
20. I have experienced thought blocking
21. I have felt lost
22. I have felt absent, as if I were living in my own world
23. My thoughts have been moving quickly
 
Re: the Brain Fog Scale

Numbers 4 and 5 could be for other reasons than mental fatigue so I find it strange it’s already definitively categorised as such.

And of the entire confusion section, only 19 is confusion and the rest don’t fit this definition at all to my mind.
 
«I have felt mentally exhausted» and «I have felt fatigued» is the same question. I would assume fatigue here to mean mental fatigue, since its written under the category «mental fatigue» on a brain fog questionnaire.

«I couldn’t think clearly» and «difficult to organise thoughts» would be close to duplicates for me as well.

While «daydreaming» is my favorite way to spend time, and brainfog holds my daydreaming back from it’s full potential.

It doesn’t make sense to me that inability to think logically, something that has a devastating impact on your life, could give you the same amount of points as daydreaming.

This scale doesn’t measure the devastation that my brainfog is at all. And I think people I know without ME/cfs, who work full time but maybe have undiagnosed ADHD, would score quite high on this questionnaire as well.
 
I'm guessing this will be quite individual, but yeah that list really looks more like a set of complaints I would have had about my ADHD before I developed ME/CFS. Agree completely @rainy about daydreaming. That may actually be a good test case for differentiating ADHD type cognitive problems vs whatever's happened in ME/CFS.

Now workshopping the ScoutB brain fog scale...

Thinking-is-broken brain fog
1. Trying to turn a vague notion into a coherent thought is often extremely taxing for me.
2. Something is wrong with making even minor decisions, the click of 'yes that one will do' never comes.
3. Novel thoughts do not seem to be arising naturally the way they used to, my head feels quiet and my thoughts repetitive.
4. I often cannot remember the task I am trying to do while executing the task. For example, if I need a piece of info from an email, I cannot hold the specifics of what I'm looking for in my mind while also navigating there.
5. Minor repetitive mental tasks will make me feel inexplicably ill after a short time, such as sorting email or transcribing a video.
6. Following what someone is saying is often impossible. I can't remember what they just said or what I just said or the topic of conversation.

Experiencing-stimuli brain fog
1. I cannot keep up in real time with moving objects around me, such as would occur when walking the dogs, or driving.
2. Trying to watch a movie or listen to music can be strangely unpleasant and even kind of mentally painful.
3. There is a frequent (or constant) feeling of not being wholly awake/present, or of being somewhat sedated.

Severe-brain-empty brain fog (was in this state for a while, thankfully not so much the past couple years)
1. My mind feels almost totally empty, my thoughts are few, rudimentary, and vanish in the ether.
2. I don't experience my usual opinions or responses to things that happen around me.
3. I cannot see 'ahead' somehow, if I need to make a minor decision I cannot even generate the options.
4. I spend a lot of time staring into space without thought.
 
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