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The Link Between Mould Exposure and Brain Fog: What the Research Says

Uncategorized May 28, 2023

Introduction to Brain Fog

According to Google Trends, worldwide interest in the search term "brain fog" has increased significantly in recent years. What's more, the addition of the search term "mould + brain fog" has shown even more significant increases in searches. This suggests that people are increasingly looking for connections between mould exposure and brain fog. The trend has accelerated during the COVID-19 pandemic, likely due in part to concerns regarding indoor air quality as more people are spending time indoors or to the introduction of vaccines or the impact of more frequent illnesses.

For example, look at the worldwide search trend for the term "brain fog" over the past 5 years.

But it's not just the COVID era that has contributed to this trend, look at the precise search term: "mould + brain fog", again, worldwide over the past decade:

So What is Brain Fog?

Have you ever experienced the frustrating phenomenon of brain fog, where your cognitive abilities seem clouded and sluggish? While brain fog can stem from multiple factors, recent research has shed light on a potential link between mould exposure and this cognitive symptom. As searches for "brain fog" and "mould + brain fog" continue to rise, it is essential to explore the relationship between these two phenomena. In this comprehensive guide, we will delve into the research and provide insights on how mould exposure can contribute to brain fog and what you can do about it.

The Impact of Mould Exposure on Cognitive Function:

One notable study exposed mice to toxic black mould (Stachybotrys chartarum) and found concerning effects on cognitive function and brain inflammation.

The study revealed that inhalation of nontoxic mould spores caused significant deficits in long-term memory, while inhalation of toxic spores increased motivation to reach a platform. Furthermore, brain inflammation was found to be significantly correlated with behavioral changes in both groups of mould-exposed males. These findings suggest that mould inhalation can disrupt cognitive processing in various ways, with brain inflammation playing a significant role.

This is the 2023 research study, but interested readers should also look at the findings from their earlier paper which I summarise below.

No research had to date explored the effects of controlled mould exposure on brain function or provided a mechanism of action. Mould exposure symptoms are considered similar to innate immune activation symptoms. The scientists hypothesised that repeated, measured dosages of hazardous and benign mould stimuli would activate innate immunity and generate neurological, cognitive, emotional, and behavioural symptoms.

Similar to their 2023 experiment, in the earlier study, mice were intranasally given whole, lethal Stachybotrys spores, extracted, harmless spores, or saline. As expected, intact spores boosted hippocampal interleukin-1β immunoreactivity. Both spore types lowered neurogenesis and induced dramatic contextual memory deficits in young mice, while reducing pain thresholds and increasing auditory-cued memory in older animals. Nontoxic spores also caused anxiety. Hippocampal immune activation was associated with reduced neurogenesis, contextual memory impairments, and auditory-cued fear memory. Innate-immune activation may explain how toxic and nontoxic mould skeletal components induced cognitive and emotional problems. 

Beyond Brain Fog: The Wide Range of Symptoms:

Mould exposure can result in a range of symptoms that extend beyond brain fog. Respiratory difficulties, skin irritation, and fatigue are among the commonly reported physical manifestations. However, mould exposure has also been linked to more profound, long-term effects on cognitive health. These effects include memory loss, insomnia, anxiety, depression, trouble concentrating, and confusion. Brain fog often serves as a prominent symptom, accompanied by other cognitive impairments such as poor concentration, lack of focus, and forgetfulness.

The Mechanisms Behind Mould-Induced Brain Fog:

The impact of mould on cognitive function is attributed to the presence of mycotoxins, which can traverse the blood-brain barrier, leading to neurological issues such as inflammation, oxidative stress, and damage to the central nervous system. These changes can contribute to the constellation of symptoms commonly associated with brain fog. Additionally, mycotoxins have the capacity to disrupt the balance of neurotransmitters in the brain, potentially leading to depression, anxiety, and sleep disorders.

Taking Control: Prevention and Treatment:

Reducing the risk of mould exposure is crucial for safeguarding your cognitive health. Here are a few proactive steps you can take:

  1. Maintain a dry and well-ventilated home: Mould thrives in environments with high humidity, so ensure proper ventilation and address any leaks or water damage promptly.

  2. Use dehumidifiers: Install dehumidifiers in areas prone to dampness to maintain optimal humidity levels and discourage mould growth.

  3. Clean up visible mould promptly: If you spot mould, clean it up using appropriate methods, such as a mixture of water and bleach. Wear protective gear and ensure adequate ventilation during the cleaning process.

  4. Professional inspection: Consider having your home professionally inspected for mould if you have concerns about indoor air quality. This is particularly relevant where you or family members are experiencing unusual health symptoms (and not just brain fog) which can't be easily explained.  It is also strongly recommended if you are in a tenancy situation and know there are 'known' water ingress/damage building-related problems that aren't being addressed.  Similarly, if your home is under construction and there is visible mould, it's a good idea to do an inspection so the builder can fix the problem and return the building to a normal mould ecology before handover. 

If you suspect that your brain fog and related symptoms may be due to mould exposure, consult a healthcare professional for guidance and support. Treatment for mould toxicity often involves binding agents, antifungals, and metabolic support supplements.


Brain fog, although frustrating, can serve as a warning sign of a larger underlying issue. The evolving research on mould exposure and cognitive function highlights a potential link between the two. By prioritizing good indoor air quality, promptly addressing mould issues, and seeking professional guidance you can overcome the challenges of mould-induced brain fog (and other potential health impacts) and regain mental clarity for improved overall well-being.


Harding CF, Liao D, Persaud R, DeStefano RA, Page KG, Stalbow LL, Roa T, Ford JC, Goman KD, Pytte CL. Differential effects of exposure to toxic or nontoxic mold spores on brain inflammation and Morris water maze performance. Behav Brain Res. 2023 Mar 28;442:114294. doi: 10.1016/j.bbr.2023.114294. Epub 2023 Jan 10. PMID: 36638914. and

Harding CF, Pytte CL, Page KG, Ryberg KJ, Normand E, Remigio GJ, DeStefano RA, Morris DB, Voronina J, Lopez A, Stalbow LA, Williams EP, Abreu N. Mold inhalation causes innate immune activation, neural, cognitive and emotional dysfunction. Brain Behav Immun. 2020 Jul;87:218-228. doi: 10.1016/j.bbi.2019.11.006. Epub 2019 Nov 18. PMID: 31751617; PMCID: PMC7231651.

Rea WJ. A Large Case-series of Successful Treatment of Patients Exposed to Mold and Mycotoxin. Clin Ther. 2018 Jun;40(6):889-893. doi: 10.1016/j.clinthera.2018.05.003. Epub 2018 May 31. PMID: 29861191.



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