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Why do I have a Brain Fog? 

Why do I have a Brain Fog? 

Why do I have a Brain Fog? 

Brain fog, also described as mental fatigue, is a symptom of other medical conditions. It’s a type of cognitive dysfunction involving:

  • memory problems
  • lack of mental clarity – slow thinking or not thinking clearly
  • poor concentration
  • inability to focus 
  • feeling confused or forgetful
  • a kind of haziness or mental fatigue

When is brain fog a problem?

Depending on its severity, brain fog can interfere with daily life. 

“Research suggests that one in seven adults between the ages 18 to 39, and one in four adults older than 39, will experience some short-term memory loss.” (1)

Brain fog can sometimes be a normal occurrence, especially in times of stress or poor sleep, but if you are finding that you are often struggling with mental clarity, it may be a sign that you need address your overall health.

Functional Medicine can help by using advanced testing in the following areas:

  • hormones
  • digestive tract
  • nutrition
  • detox function
  • neurotransmitters
  • chronic inflammation 
  • metabolic health 

Along with an in depth look at your health history, we can ascertain the status of these systems and uncover how they are impacting your cognition.  

Common causes of brain fog

Common underlying conditions that can impair thinking skills include:

  • Brain inflammation

The blood-brain barrier is a thin membrane that protects the brain, allowing tiny particles in and out of the brain. When it becomes too permeable or “leaky,” just as the gut lining can become leaky, larger particles can get in the brain and trigger the brain’s immune system, resulting in inflammation.

Brain inflammation can also result from:

  • Chronic systemic (throughout the body) inflammation
  • Blood sugar imbalances
  • Hypothyroidism
  • Gut infections
  • Heavy metals and other toxins
  • Autoimmune disease
  • Stress and lack of sleep
  • Head injuries or stroke (2)
  • Stress

Oxidative stress

Oxidative stress describes the state caused by two things: excessive reactive oxidative species (ROS) production or a reduced anti-oxidative defence system.

One or both conditions can lead to cellular chaos, cell death, permanent tissue damage and chronic disease. ROS are created by anything that causes stress: for example, poor diet, smoking, sedentary behaviour, environmental factors, psychological stressors and abnormal sleep patterns.

Oxidative stress affects the brain’s cortex, hippocampus and striatum, which govern your memory network. (3)

Chronic stress, excessive anxiety or depression

Chronic stress, excessive anxiety (when worry is excessive) or depression (feelings of extreme sadness or hopelessness that last more than two weeks) can increase blood pressure, weaken the immune system and trigger depression. They can also cause mental fatigue. 

When your brain is exhausted, it becomes harder to think, reason and focus. 

  • Toxins

Metal toxicity may be one of the most common causes of brain fog. Copper, mercury, aluminium, cadmium and lead are the most potent metals resulting in such toxicity. Toxic chemicals like solvents and pesticides severely affect brain functioning and may lead to brain fog. Bowel toxicity due to improper digestion, constipation or intestinal function can also result in brain fog. (4)

  • Lack of sleep or poor quality sleep

Poor sleep quality can also interfere with how well your brain functions. Aim for eight to nine hours of sleep per night. Sleeping too little can lead to poor concentration and cloudy thoughts.

Obstructive sleep apnoea causes people to stop breathing periodically while they sleep. The classic symptom is daytime sleepiness. Another common symptom is loud snoring, often accompanied by gasping for breath. Sleep apnoea puts you at risk for stroke and heart disease, and it can also cause fuzzy thinking. (5)

  • Hormonal changes

Progesterone and oestrogen

Hormonal changes can also trigger brain fog. Levels of the hormones progesterone and oestrogen increase during pregnancy. This change can affect memory and cause short-term cognitive impairment. 

Similarly, a drop in oestrogen level during menopause can cause forgetfulness, poor concentration, and cloudy thinking.


An underactive thyroid gland occurs when your thyroid gland isn’t producing enough thyroid hormones—thyroxine (T4) and triiodothyronine (T3 – many body functions become sluggish, including brain function. This can lead to fuzzy thinking and forgetfulness.

  • Diet

Vitamin B

Diet can also play a role in brain fog. Deficiencies in B vitamins can cause brain fog.  Vitamin B1, B2, B6, B9 and B12 deficiencies can contribute to fatigue and brain fog.  

Vitamin B12 is essential for healthy blood and nerve function. We get B12 from eating meat, eggs, and milk and other dairy products. But as we age, it gets harder to absorb B12. This can cause abnormally low B12 levels in the blood and lead to fuzzy thinking and other symptoms, such as muscle weakness. Some people have a rare form of anaemia that makes it very hard to absorb B12.

Vitamin B-12 supports healthy brain function, and a vitamin B-12 deficiency can bring about brain fog. 

Inflammatory foods

Inflammatory foods can increase pro-inflammatory cytokines in the blood and brain, leaving you with low-grade inflammation that can manifest as a foggy brain. In some cases, being overweight can contribute to inflammation.

Inflammation stresses your body and rapidly uses up nutrients – specifically the B vitamins, magnesium, and vitamins C and E.

Food allergies and sensitivities 

If you have food allergies or sensitivities, brain fog may develop after eating certain foods. Possible culprits include:

  • MSG
  • aspartame
  • peanuts
  • dairy

Removing trigger foods from your diet may improve symptoms.

  • Medication side effects

Brain fog may be a known side effect of any medication you may be taking. Lowering your dosage or switching to another drug may improve your symptoms.

Some drugs that block the effects of a neurotransmitter responsible for stimulation and activity in the brain, known as anticholinergics, may result in confusion. 

These include medications for incontinence, allergies, depression and muscle spasms. Also, medications that have a sedative effect may make it hard to concentrate, such as pain or sleep medications.

Brain fog can also occur after cancer treatments. This is referred to as chemo brain.

  • Medical conditions

Medical conditions associated with inflammation, fatigue, or changes in blood glucose level can also cause mental fatigue. For example, brain fog is a symptom of chronic fatigue syndrome, which involves persistent fatigue for longer than six months. 

Conditions that may cause brain fog include:

  • fibromyalgia 
  • anaemia
  • depression
  • diabetes
  • Sjögren syndrome
  • migraines
  • Alzheimer’s disease
  • hypothyroidism
  • autoimmune diseases such as lupus, arthritis and multiple sclerosis
  • dehydration (6)

When you’re struggling with fuzzy thinking, lifestyle changes such as exercise, meditation and dietary changes can bring more clarity.

  • Chronic infections

For some people, they may only be suffering from brain fog, but in fact, they could have a viral, fungal or bacterial infection. One of the most common lingering infections is an overgrowth of Candida yeast that occurs naturally in your body.

Candida is a fungus that hides in your mouth and gut. It can overgrow from stress, from a high-sugar diet, or from antibiotic use that leads to an imbalance of “good” versus “bad” bacteria in the gut.

Because your gut communicates directly with your brain, miscommunication can alter your memory capabilities. (7)

How can you combat brain fog?

There are a number of Functional Medicine tools and lifestyle changes that can help you reduce, if not eliminate brain fog. They include: 

  • Having your inflammation levels tested
  • Balancing your neurotransmitters
  • Reducing inflammation by removing inflammatory foods and replacing them with nutrient dense substitutes
  • Testing and healing your gut, removing bacterial overgrowth, promoting beneficial bacterias, healing intestinal permeability etc
  • Using herbs to heal, balance the immune system and boost energy levels
  • Managing your stress
  • Avoiding toxins
  • Getting into a good pattern of quality, and enough, sleep
  • Supporting methylation with B Vitamins and supporting nutrients
  • Using natural medicines prescribed by your Functional Medicine health practitioner.
  • Getting more exercise
  • Cutting back on, or eliminating, alcohol
  • Avoiding sugar
  • Boost your Vitamin B intake to protect the brain, enhance communication and lower the level of homocysteine in the brain.
  • Boosting your Vitamin D intake to help clear brain fog, lift depression and enhance memory and clarity.
  • Trying an elimination diet
  • Removing grains and all forms of gluten from your diet
  • Incorporating more eggs, organ meat and coconut oil into your diet
  • Switching to grass-fed dairy (8)
  • Consuming more omega-3 essential fatty acids – combats fatigue, poor memory, mood swings, and depression.
  • Taking magnesium to calm the central nervous system, block stress hormones and combat migraines.


Your Functional Medicine health practitioner may also prescribe you other supporting supplements including:

  • Citicoline – improves the blood blow to the brain and also prevents the free radical-induced damage to brain cells. Must be used in low quantities.
  • Rhodiola Rosea – assists in alleviating mood disturbances and absent-mindedness
  • Phosphatidylserine – improves short term and long term memory functions
  • N-Acetyl L- Tyrosine: helps relieve the symptoms of brain fog by enhancing the level of neurotransmitters in the brain.
  • Gotu kola – helps with mental fatigue, anxiety, depression, memory loss, and insomnia
  • Coenzyme Q10 (CoQ10) – fuels your cells’ mitochondria to boost brainpower
  • Curcumin – boosts attention and memory, reduces inflammation, helps treat depression
  • Bacopa – improves memory and cognitive functioning reduces stress and anxiety, helps with symptoms of ADHD (9)

Be sure to consult with your health practitioner before you start any of the above supplements.

How Functional Medicine can help you

At Advanced Functional Medicine, we can support you with accurate, targeted testing to uncover the causes of your brain fog. Once we know how any health conditions are impacting your cognitive ability, we can start to work on returning you to better mental clarity and sharpness of mind.  

Our Functional Medicine approach is focussed on balancing the biochemistry and returning balance to the body to resolve brain fog at its root cause.

Find out more by phoning us or filling out the form below.

The above information is intended to be general, educational advice only, on topics which are of interest to us. It is not intended to represent specific or individual health or medical advice and is not specific to your situation. The below information is educative and is not intended to advertise any service.

Before making any decisions in relation to your health, you should always discuss your individual situation with your own health practitioners to ensure that any advice you have read is right for you.

Jarrod Cooper – ND

Jarrod Cooper – ND

Jarrod Cooper - ND is the founder of Advanced Functional Medicine Australia. He is a Naturopathic Doctor with extensive functional medicine training from leading practitioners in the USA and worldwide.

He is leading the way with advancements of functional medicine, clinically implementing worldwide best practices in Functional Medicine throughout Australia.

Jarrod consults in person from Perth, Western Australia and also online via Telehealth throughout Australia and worldwide.

If you are looking for personalised treatment, we highly recommend contacting Jarrod Cooper’s Advanced Functional Medicine clinic in Australia.

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