Common Causes of Brain Fog and How to Fix It

person with brain fog

A lack of mental sharpness. A hazy memory. Poor concentration. These are all signs of “brain fog,” a common complaint that can make you feel like you’re underwater or sleepwalking through your days.

It makes it challenging to do your best at work, can bring out the worst in you in relationships, and can make simple tasks seem overwhelming. Brain fog isn’t considered a medical or psychiatric condition, rather it’s a symptom of mental health disorders and other problems. What causes brain fog and how can you fix it? Here’s what you need to know.

Brain fog isn’t considered a medical or psychiatric condition, rather it’s a symptom of mental health disorders and other problems. Click To Tweet


Here are 10 of the most common causes of brain fog.

  1. Sneaky food allergies

The foods you eat can either enhance mental clarity or leave you feeling dull and drained. High-glycemic foods that cause blood sugar levels to spike and subsequently crash are common culprits that zap mental energy.

In some people, food allergies or sensitivities contribute to brain fog. The worst offenders include gluten, soy, dairy, corn, sugar, MSG, and artificial dyes and sweeteners.

They can lead to many mental symptoms, including cognitive fatigue, slowed thinking, lack of focus, irritability, agitation, anxiety, and depression, among others.

Fog Buster: To determine if food allergies are a problem, try an elimination diet. Stop eating the offenders mentioned above for one month then re-introduce them one by one to see if they impact your mental clarity.

  1. Rampant stress

When chronic stress becomes overwhelming it can mess with your mind, steal your focus, and leave you with swirling thoughts.

With unrelenting stress, the stress hormone cortisol gets stuck on high and leads to detrimental changes that exhaust the brain. This leaves you with mental fatigue.

Fog Buster: Getting stress under control with relaxation techniques can help clear your head.

  1. Untreated depression

Having clinical depression is commonly associated with memory problems, trouble concentrating, and mental confusion. Research in the Annals of General Psychiatry shows that some form of cognitive dysfunction is present up to 94% of the time during the course of depressive episodes.

Fog Buster: Finding out which of the 7 types of depression you have and addressing any underlying factors contributing to the condition may promote sharper thinking.

  1. The pills you’re popping

A number of over-the-counter drugs (think sleeping pills and antacids) and prescription medications (such as cholesterol-lowering drugs, anti-anxiety pills, or chemotherapy) can have negative cognitive effects.

For example, sleep aids can leave you with a “hangover” effect that clouds your thinking. And cancer-fighting drugs are so well-known for causing cognitive fuzziness, they have earned the name “chemo brain.”

Fog Buster: Speak with your physician about medication alternatives that don’t compromise cognitive function. If you must take certain medications, get serious about enhancing brain health with other lifestyle changes, such as regular exercise, avoiding exposure to toxins, eating nutrient-dense foods, and more.

  1. Lack of sleep

As you sleep, your brain is busy performing important processes that help consolidate learning and memory. When you don’t get the sleep you need, your brain can’t complete this work, and it lowers your mental horsepower.

Losing out on a single night’s sleep can leave you feeling groggy. When sleep deprivation becomes chronic, it is associated with memory loss, trouble concentrating, and lack of focus.

Fog Buster: Make sleep a priority and aim for 7-8 hours each night. Develop an evening routine to promote restful sleep.

  1. Hormonal imbalances

People with neurohormonal deficiencies tend to struggle with cognitive issues. For example, when thyroid, estrogen, or testosterone levels are low, it is associated with attentional issues, difficulty concentrating, and forgetfulness.

At Amen Clinics, functional brain-imaging studies with SPECT show that people with hypothyroidism have decreased activity in the brain. On SPECT scans, this pattern is also linked to brain fog and cognitive impairment.

Fog Buster: Have your hormone levels checked and optimize them if necessary.

  1. A past head injury (even one you may have forgotten)

Did you know that a blow to the head, a fall off a ladder, or a sports concussion can cause fuzzy thinking months, years, or even decades later? You may not even recall a head injury, but if you’re struggling with persistent brain fog, it’s a good idea to investigate if underlying brain trauma may be causing it.

Functional brain imaging with SPECT can detect hidden injuries to the brain that may be connected to cognitive problems. At Amen Clinics, approximately 40% of all patients who get SPECT scans have evidence of a past head injury.

Fog Buster: Treatments, such as hyperbaric oxygen therapy (HBOT) and neurofeedback, have been shown to promote healing of traumatic brain injuries.

  1. Untreated adult ADD/ADHD

Having trouble keeping track of things, struggling to stay organized, and having difficulty staying focused are common signs of brain fog. They are also classic symptoms of adult attention-deficit/hyperactivity disorder (ADHD), also called attention-deficit disorder (ADD).

Seek professional help to find out if your cognitive issues are due to adult ADD/ADHD or to rule out this condition.

Fog Buster: Getting diagnosed is the first step to finding the best solutions for treating ADD/ADHD and the cognitive issues associated with it. Be aware that ADD/ADHD is not just one thing. Brain SPECT imaging studies show there are 7 types of ADD/ADHD and you need to know your type to find the right treatment plan.

  1. Toxic mold exposure

Feeling confused, having a hard time putting complete sentences together, and losing your train of thought are common complaints in people with brain fog. These same symptoms can also be signs of toxic mold syndrome.

Toxic mold has been associated with a host of physical, emotional, and cognitive issues like headaches, insomnia, anxiousness, depression, and memory loss.

Fog Buster: Eliminate your exposure to mold and seek help from an integrative medicine (also called functional medicine) physician. 

  1. Long COVID

Lingering brain fog, including problems with focus and attention, is one of the most common symptoms of long COVID, also called COVID-Brain. The cognitive fuzziness can persist for months or even years after infection with COVID-19.

Some people who had mild cases of infection develop severe COVID brain fog that leaves them unable to return to their pre-COVID life. The cognitive effects are so debilitating for these COVID long haulers that they can’t go back to work and are barely able to function.

Fog Buster: Adopting brain-healthy habits can be an important part of the healing process for anyone struggling with COVID-Brain.


To identify the root cause of your brain fog, you may benefit from a comprehensive evaluation that include neuropsychological testing, blood work, and functional brain imaging with SPECT.

SPECT scans show patterns of activity and blood flow in the brain that are associated with ADD/ADHD, major depressive disorder, head injuries, exposure to toxins, neurohormone issues, and more. This can be very helpful in discovering what’s causing your brain fog and in determining how to fix it.

Brain fog associated with depression, ADD/ADHD, infections, toxic exposure, and other mental health issues can’t wait. At Amen Clinics, we’re here for you. We offer in-clinic brain scanning and appointments, as well as mental telehealth, clinical evaluations, and therapy for adults, teens, children, and couples. Find out more by speaking to a specialist today at 888-288-9834 or visit our contact page here.


  1. Brain fog shouldn't be automatically connected to mental health problems until a person has such from that and any other causes such as genetic factors and nutritional deficiencies and possible heavy metals and/or toxins. I'm using acetyl-choline AKA choline to offset my MTHFR genetic variant caused brain fog. When regular doctors and/or psychiatrists aren't looking at the overall health for people and even use inadequate MD labwork, it's frustrating to be a 'double victim'. Brain fog is part of the MTHFR-related cellular damage. I'm thankful that alternative doctors like functional medicine, integrative, naturopathic, holistic, etc. care more and have better testing to find our missing clues but it's still not enjoyable to be stuck in between the MD gaps. I survived but trying to network helpful information to help others to find relief and survival vs. being 'forever patients' and trying to deal with our various symptoms that conventional MDs don't bother to help us with. We need a merging of MD training to really provide relief rather than possible indifference that can plague us. EGN

    Comment by Elinor Nosker — February 2, 2024 @ 1:44 PM

  2. Yup,

    Kinda feelin' all ten of them .

    Funny, nothing a 1800 mi, 9 day, 99 manic moments can't settle ….

    Kinda loopy for a few days, just enough to force the rest.

    Pictured most of it, just in case someone suggests they might wanna perform a #2, second SPECT. The resultant rastors just might make the vectors make sense of such the supposed nonsense.

    B Nice

    Comment by Alabama Brian — February 2, 2024 @ 2:38 PM

  3. excellent topic!

    Comment by Doug Morris — February 2, 2024 @ 5:20 PM

  4. How much does a SPECT cost?

    Comment by Sandy Jagoda — February 2, 2024 @ 5:46 PM

  5. Prеtty! This has been ɑ reаlⅼy w᧐nderful aгticlе.
    Thank you for supplying these detаils.

    Comment by eyed — February 2, 2024 @ 5:48 PM

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