What is brain fog and what causes it?

 Extract from ABC News

Health

ABC Health & Wellbeing

By science reporter Suzannah Lyons

Posted Yesterday at 1:15pm

It's a common term, but brain fog can be used to describe a range of different symptoms.(Getty Images: Ponomariova_Maria)

Having difficulty concentrating.

Feeling confused or forgetful.

An inability to focus.

Slow thinking or not thinking clearly.

A kind of haziness or mental fatigue.

Any one of these symptoms can be described as brain fog, says clinical neuropsychologist Caroline Gurvich of Monash University, whose research focuses on cognition and women's mental health.

But although it's a term you may hear quite a lot — from people undergoing chemotherapy to COVID-19 long-haulers — it's not one that's formally recognised in medicine or psychology.

"It's a lay term," Dr Gurvich says.

"It's kind of the subjective experience of not thinking clearly, feeling a bit foggy in the brain."

It's a feeling that our brain isn't working to its cognitive potential or to its normal level, says Con Stough, a cognitive neuroscientist at Swinburne University.

Another way we can experience it, Professor Stough says, is when we get that feeling that we're really slowing down in terms of how we process information.

What causes brain fog?

Brain fog is associated with a range of different causes, Dr Gurvich says, from medical conditions like fibromyalgia, hormonal changes related to menopause and the menstrual cycle, to nutrition, stress, anxiety and fatigue.

Chronic stress may contribute to the feeling of brain fog that's reported by people living under extreme lockdown during the pandemic.

And brain fog also seems to be common in people who have had coronavirus , months after their infection has cleared.

There's still a lot we don't know about how coronavirus affects the brain.

But in terms of in terms of brain fog more generally, it's not even clear whether this subjective experience actually relates to an objective neuropsychological or cognitive change.

"We don't know that yet," Dr Gurvich says.

"And it will depend [on the] different reasons people experience brain fog, as to whether there's an actual change to someone's cognition or just a feeling that they're not thinking clearly."

A lack of sleep can impact how well we can think the next day.(Unsplash CC: Annie Spratt)

In Professor Stough's opinion, lack of sleep and poor sleep quality are the biggest contributors to brain fog.

"Particularly these days, people are not getting the right amount of sleep, and anything can disrupt sleep," he says.

He also thinks lots of medications can increase brain fog, and nutrition definitely does.

While we don't really understand how these things influence brain fog, he says, "it's interesting that all those things also affect the microbiome as well".

Where did the term brain fog come from?

Dr Gurvich really didn't hear the term "brain fog" used until a few years ago, although it seems to be used a lot more now, she says.

A search for the term in the scientific literature reveals some early references to it in the mid- to late-1990s, in the context of people describing their experiences with chronic fatigue syndrome.

ABC language researcher Tiger Webb says the word 'fog' first appears in reference to weather events in English in the mid-16th century, according to the Oxford English Dictionary, and a figurative sense develops almost immediately.

"People speak of 'the thick fog of ignorance' and so on," he says.

"In fact, the earliest sense of the adjectival form 'foggy' mostly refers to mental states."

However, the dictionary's earliest citation for "brain fog" is from 1853, in a Pennsylvanian newspaper called the German Reformed Messenger.

Dr Gurvich is researching the cognitive changes that occur during menopause and across the menstrual cycle.

"There is a reasonable proportion of women who go through the menopause transition and experience cognitive change, and that is associated with an objective cognitive decline," Dr Gurvich says.

This decline is subtle. It's not like a mild cognitive impairment which can be a precursor to Alzheimer's, but it is enough to have a substantial impact on someone's life, she says.

"Sometimes small changes in thinking can have a big impact on your quality of life."

Dr Gurvich and her colleagues are still trying to understand what causes this hormonally-induced brain fog but they do have some ideas.

"We think it's because of the fluctuations and then declining hormones, such as oestradiol, which is a type of oestrogen, that's supposed to have positive effects on brain health," she says.

When that drops off at menopause, they think it has a negative impact on women's thinking skills.

Other menopause symptoms may also independently or additionally exacerbate this feeling of brain fog.

Sometimes it's easy to tease apart what might be causing someone's brain fog and sometimes it's not.

What can you do to beat it?

If you have brain fog caused by a medication or a medical condition, including COVID-19, speak to your doctor about whether it warrants further investigation and if there are strategies you can employ to deal with it.

For brain fog triggered by other causes, there are some common things you can do to try and overcome it, Dr Gurvich says.

First of all, take a look at your lifestyle.

"Make sure your diet is OK, and you're sleeping well, and you're getting exercise and routine, and trying to reduce stresses," she says.

In terms of trying to improve your brain and cognitive functioning, look at what you can do to reduce your distractions.

For example, switching off your phone while you're working, or your email and social media notifications, so you can just focus on one thing at a time.

"If you've got big tasks that are overwhelming, you can break them down into smaller, more manageable tasks and write checklists," Dr Gurvich says.

And remember, when it comes to brain fog you're not alone.

"We all experience brain fog," Dr Gurvich says.

"Certainly on its own, it might not necessarily be something to be concerned about."

But if you're at all worried about it, she recommends seeking help from your GP.