Brain fog: physical causes worth ruling out

You know what you want to say, but the right word won't come. You walk into a room and forget why. You read the same paragraph twice before it sinks in.

Brain fog is a general term for these kinds of changes in thinking, memory and concentration. It can happen during periods of poor sleep, stress or hormonal change, but there are physical factors that can play a part too.

Nutrient deficiencies, thyroid problems, changes in blood sugar and some hormonal changes can all affect how you think and feel. Looking at these factors can sometimes provide useful context, particularly if brain fog is becoming more frequent or is a noticeable change for you.

This guide looks at some of the physical causes worth considering and the tests that may help provide a clearer picture.

What does brain fog feel like?

Brain fog isn't a medical diagnosis. It's a general term for changes in how clearly you think, remember or concentrate.

You might notice that you:

• Struggle to concentrate on tasks that usually feel straightforward
• Forget names, appointments or things you've just been told
• Lose your train of thought during conversations
• Find it harder to make decisions
• Need longer to process information
• Find yourself searching for familiar words Occasional forgetfulness is part of being human. It's more useful to pay attention to a pattern rather than one or two absent-minded moments.

If these changes are persistent, getting worse or beginning to interfere with everyday life, it's worth discussing them with a healthcare professional. The NHS lists several possible causes of memory problems, including stress, anxiety, depression, sleep problems, an underactive thyroid and some medicines.

Sleep, stress and everyday factors

Before looking for a physical cause, consider what's been happening in your life recently.

Poor sleep can make it harder to concentrate and remember things. Stress can have a similar effect, particularly when your mind is constantly occupied with other things.

Your routine can also make a difference. Eating irregularly, drinking more alcohol than usual or going through a particularly demanding period can all leave you feeling less mentally sharp.

If brain fog continues despite changes to your routine, there are physical factors worth considering too.

Low iron and brain fog

Iron helps your body make haemoglobin, which carries oxygen around the body. When iron levels are low, you can develop iron deficiency anaemia, which may cause symptoms including tiredness, headaches and difficulty concentrating.

A blood test can check your blood count and iron stores, depending on what your healthcare professional thinks is appropriate.

Bluecrest data shows that iron-related findings can be relatively common. Iron deficiency was around seven times more common in women than men in Bluecrest's data, affecting 4.7% of women compared with 0.6% of men.

This is Bluecrest customer data and isn't representative of the UK population as a whole.

Vitamin B12 and folate

Vitamin B12 and folate are important for your nervous system and the production of healthy red blood cells.

A deficiency can cause a range of symptoms, including problems with memory, understanding and judgement. These symptoms can occur even when someone doesn't have anaemia.

There are several reasons someone might have low B12 or folate. Diet can play a role, but absorption problems and some medicines can also affect B12 levels.

Bluecrest's Vitamin & Mineral Deficiency Test includes vitamin B12 and folate alongside vitamin D and iron stores.

Your thyroid and concentration

Your thyroid produces hormones that influence many of the body's processes.

An underactive thyroid can cause difficulty concentrating or thinking clearly alongside symptoms such as feeling unusually cold, weight gain, constipation, low mood or changes to your hair and skin.

Brain fog on its own doesn't mean you have a thyroid problem. If you're noticing several changes at the same time, however, thyroid function is one area that may be worth checking.

A Bluecrest Thyroid Function Test measures thyroid-stimulating hormone (TSH) and free thyroxine (FT4).

Hormonal changes and brain fog

For some people, brain fog appears alongside hormonal changes.

This is particularly common during perimenopause and menopause. The NHS lists memory problems and brain fog among the symptoms that can occur during this time. Sleep problems and mood changes can also affect concentration.

You may notice that you're forgetting things more often, struggling to concentrate or finding it harder to keep track of several things at once.

If these changes are happening alongside other menopause symptoms, a healthcare professional can help you understand whether hormonal changes could be contributing.

Other factors worth considering

Brain fog can have many possible explanations, so it's useful to consider what's changed in your health and routine. Other factors can include:

• Medication: some medicines can affect alertness, concentration or memory.
• Illness: brain fog can sometimes follow a period of illness.
• Mental wellbeing: anxiety, depression and prolonged stress can affect concentration and memory.
• Sleep problems: regularly disrupted sleep can leave you feeling mentally slower during the day.
• Blood sugar: changes in blood sugar can sometimes affect how you feel and concentrate. Looking at your symptoms as a whole is often more useful than focusing on one possible cause.

When to get brain fog checked

Occasional forgetfulness is very common. If you're regularly struggling to remember important information, concentrate at work or manage everyday tasks, it's worth getting some advice.

It's particularly worth speaking to a GP if your memory or concentration problems:

• Are persistent or getting worse
• Are affecting your work or everyday activities
• Are accompanied by other unexplained symptoms
• Started after a new medicine or significant change in your health
• Are concerning you or people close to you A GP can look at your symptoms as a whole and decide whether further assessment or blood tests would be useful.

A private health assessment shouldn't replace medical advice if you're experiencing persistent or significant changes in your memory or thinking.

How health assessments can provide useful context

There isn't one blood test that can explain brain fog. The useful tests depend on your symptoms and overall health.

A Bluecrest Health Assessment brings together a range of blood tests and physical measurements, depending on the package you choose. These can include checks covering areas such as blood pressure, cholesterol, blood sugar, liver function, kidney function and iron.

Results are presented using a straightforward green, amber and red flag system, making it easier to see which areas are within the expected range and which may be worth paying attention to.

Bluecrest has delivered more than 1.3 million Health Assessments, generating 19.9 million blood results and 2.7 million physical results.

The aim isn't to put a label on every symptom. It's to give you clear information about your health that can help you understand where things stand and decide what you want to focus on.

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