Mould and mental health: what is established about anxiety and depression

Mould and mental health sound like two separate worlds at first. Until you live in a damp home yourself.

You unlock the door, and there it is again, that smell. Slightly musty, a little like a cellar.

Behind the wardrobe in the bedroom, the wall has turned dark. In the morning there is water on the window. You wipe it away, and the next morning it is back.

At night you lie awake. Your nose is blocked, your head is full. You work out whether the heating bill will be affordable. You would rather not invite anyone over any more.

Many people know this pattern. And at some point the question comes up that probably brought you here: can mould affect your mental health? Does it make you anxious, does it make you depressed?

The answer has several layers. In studies, dampness and mould go along with more depressive symptoms, more psychological distress and poorer sleep. Whether the mould itself is the cause remains open. The data point more towards several pathways at the same time.

Here you can read what has been shown in humans, what has only been shown in animal experiments, what you can do and where the limit lies.

Mould and mental health: what the large European study shows

Perhaps you have already read that mould makes you depressed. That sounds clear-cut. The evidence is more nuanced.

Almost every discussion leads back to a paper from 2007. The German mould guideline also refers to it when it comes to depression.

An odds ratio of 1.4 does not mean that 40 percent of people in damp homes become depressed. It means that the odds of reporting depressive symptoms were about 1.4 times as high as in the comparison group. Imagine a set of scales: a damp home is not a switch that tips them over, but an additional weight.

One detail is rarely mentioned. The highest exposure level did not have the highest odds ratio. For extensive dampness it was the lowest at 1.34, and according to Gatto's review its confidence interval ranged from 0.97 to 1.85 and included 1. According to the same review, the test for trend was significant (p = 0.032), but the values did not rise step by step. So the study does not show a clean, stepwise dose-response relationship.

What "mediated" means in this study

Mediated is a statistical term. An association becomes smaller when a third variable is added to the calculation. That is not proof of a biological mechanism.

The researchers found two such variables, whose shares appeared to add up. The sense of control: can I change something about my housing situation, or am I at its mercy? And physical health, from coughing to a blocked nose.

With both variables in the model, a remainder was left, and according to Gatto the odds ratios were then 1.28, 1.34 and 1.09. Because this is a cross-sectional study, the direction remains open.

The finding is not new. As early as 1996, Hopton and Hunt reported from a disadvantaged area of Glasgow that, after accounting for confounders such as income and chronic illness, damp problems were independently associated with higher scores on the General Health Questionnaire, a questionnaire on psychological distress [Cross-sectional].

A second review led by Brooks included 30 studies. In 21 of 24 studies the association was significant in simple analyses, and in 13 of 17, dampness or mould remained an independent predictor in multivariate models as well [Scoping Review]. The authors still do not draw a causal conclusion, because of the confounders. With observational data, this restraint is well founded.

And now you know why an odds ratio of 1.4 is not a verdict about you, but a sign that your home can be one weight on the scales.

Anxiety, psychological distress and sleep: the further data

The nights are often the moment when everything shows. Your head won't settle, your nose is blocked, and the morning feels heavy before it has even begun.

A cross-sectional study is a snapshot. Data that follow the same people over years are stronger.

In Germany, based on self-reports, roughly one in five to one in six homes is affected by dampness or mould [Review, guideline-based]. So you are not alone in this.

A second analysis of the same panel asked who is particularly affected. In people with chronic respiratory disease, a damp home went along with an odds ratio of 1.27 for psychological distress, and in people with healthy airways with 1.07 [Panel, longitudinal]. That would fit a possible pathway through physical symptoms.

The pattern also shows up around childbirth. In the Taiwan Birth Cohort Study with 17,981 mothers, the prevalence of postpartum depression at six months was 16.7 percent. Mould spots went along with an odds ratio of 1.31, alongside secondhand smoke (1.18), renovating or painting (1.33) and insecticides (1.13) [Cohort, national birth cohort]. The home environment and depression were asked about at the same point in time, so this does not show a sequence in time. More on pregnancy can be found in Mould during pregnancy.

In a network analysis led by Sanders with up to 9,669 pregnant women, among all features of poor housing quality it was the feeling about one's own home that was most strongly connected with depressive symptoms [Cross-sectional, network analysis].

For children, one important cohort comes from Germany. In GINIplus and LISAplus with 4,860 children, ten-year-olds with mould in the home more often had borderline or abnormal scores on the Strengths and Difficulties Questionnaire (adjusted odds ratio 1.23, confidence interval 1.00 to 1.56), for dampness the value was 1.51, and for pets 1.48 [Cohort, two German birth cohorts]. The fact that pets were associated to a similar degree could speak against a mould-specific toxin. That is my interpretation, not a result of the study. The pathways the authors suspected, neurotoxicity and immune activation, are hypotheses.

In the Millennium Cohort Study with 11,625 children from England and Wales, dampness or condensation at nine months went along with more emotional and behavioural problems at three years, after accounting for many confounders [Cohort, Millennium Cohort Study]. The sequence in time is clearer, and the effects were small.

Mould and anxiety disorder: what exists on this

An honest answer to a frequent search query: I have not found a study with a diagnosed anxiety disorder as the outcome in ordinary everyday housing.

What does exist is thinner. The General Health Questionnaire measures anxiety and depressive symptoms together. An English housing survey, only accessible through Gatto's review, found an odds ratio of 1.25 for anxiety with year-round dampness, and no significant association with dampness in winter only. Many anxiety data also come from households after flooding and cannot be transferred to an ordinary damp home.

Qualitative studies, on the other hand, describe clearly what it feels like. In an Australian study with interviews in Melbourne and a national survey, people affected reported anxiety, stress, falling self-esteem and the feeling of no longer being safe at home [Qualitative study]. In Brooks' review, people feared health consequences and felt ashamed because their clothes or home smelled damp. Panic attacks or psychoses as a direct consequence of mould, as some websites describe them, are not supported by these studies.

Sleep as a bridge

This also shows up in children in Germany. In the LISAplus birth cohort, visible mould or dampness in 1,719 ten-year-olds went along with sleep problems (odds ratio 1.77) and short sleep duration (1.68). Without allergic rhinoconjunctivitis, only the association with short sleep duration remained [Cohort, German birth cohort, cross-sectional analysis]. So part of it appears to run through allergic rhinitis.

Why does this matter for mental health? Because persistently poor sleep is one of the best-studied risk factors for later mental illness.

A later meta-analysis led by Hertenstein with 13 longitudinal studies found insomnia to be a predictor of new onset of depression (ten studies, odds ratio 2.83) and of anxiety (six studies, odds ratio 3.23) [Meta-analysis]. The two papers are based on different collections of studies, so their figures cannot be set directly against each other.

How sleep and mood pull on each other is something I describe in Sleep and depression. For chronic insomnia there is a dedicated, structured approach in cognitive behavioural therapy for insomnia, more on this in CBT-I and sleep restriction.

And now you know why the question about your sleep often reveals more about the path from mould to mood than the question about toxins.

The big confounders: poverty, cold, noise and worries

Mould rarely comes alone. The home is damp, often cold as well, because heating is expensive. Traffic noise comes through old windows. And the letter to the property management has been lying unanswered on the table for weeks.

In research, something like this is called a confounder: a third variable that is connected both with mould and with mood. On this topic, such variables are unusually large, and they occur in bundles.

The WHO guideline states that dampness and mould can be particularly common in poorly maintained homes of people on low incomes, and recommends giving priority to remediation there in particular [Guideline]. In Denmark, in a repeated survey with 27,068 participants, problems with room temperature, noise and water damage were more common among people on low incomes. In their conclusion, the authors describe inequality by household income for all indicators assessed, including annoyance from mould, without giving a separate figure for it in the abstract [Cross-sectional, repeated].

An overview led by Evans describes how poor environmental conditions cluster among poorer people [Narrative Review].

The German National Disease Management Guideline (NVL) Unipolar Depression names low socioeconomic status, poverty, chronic stress and chronic illness as risk factors and describes a substantially higher rate of depression in cities and in rented flats than in the countryside in owner-occupied homes [Guideline]. It does not mention mould.

Then there is the cold. A review led by Liddell describes several stressors at once in cold, damp homes: worry about debt and affordability, physical discomfort from the cold, worry about health. Improvements in energy efficiency often went along with significantly better mental wellbeing, and cumulative stress is suggested as an explanation [Review].

Noise often affects the same residential areas. In a meta-analysis led by Hegewald, the risk of depression rose by 12 percent per 10 decibels of aircraft noise, while for road and railway noise the increases were 2 to 3 percent and not significant [Systematic Review with meta-analysis]. A meta-analysis led by Dzhambov rated the evidence on road traffic noise and depression or anxiety as very low quality [Meta-analysis].

And then there is time. In the British household panel with 16,234 people, mental health worsened the longer housing problems persisted, although these covered more than mould [Panel, longitudinal]. An analysis led by Taylor found that problems paying housing costs carry psychological costs of their own, beyond general financial hardship. The size was similar to that of separation or job loss [Panel, longitudinal]. This makes it understandable why an unresolved dispute over a damp home can weigh so heavily.

Can it also run the other way?

Yes. And that matters, without turning it into an accusation.

In the Danish National Birth Cohort, the home environment of 42,723 eleven-year-olds was linked with register data on their parents. Families with higher education and higher income had less mould and condensation, but water damage more often. According to the authors, affective disorders in parents in particular were strongly linked with mould [Cross-sectional, birth cohort]. This fits with the British panel, in which the association ran in both directions, and with Gatto's review.

This is easy to misread, so to be very clear: people with depression are not to blame for the mould. But exhaustion and loss of drive can make it harder to keep on top of dampness. Airing the rooms, moving furniture away from the wall, writing to the property management, all of this takes energy. If you have little of it, you can more easily end up in a cycle in which home and mood weigh on each other. The German National Disease Management Guideline describes this in general terms: a mental disorder can intensify psychosocial stress [Guideline].

And now you know why a good medical history does not only ask whether mould is present, but also what else is on the scales.

Possible biological pathways: inflammation, spores, mycotoxins

Perhaps you have read that mould inflames the brain. That sounds frightening and final. This is exactly where it pays to separate what was shown in humans, in mice and in cell cultures.

The basic idea comes from psychoneuroimmunology. Think of it like an internal sick note: the immune system can report illness to the brain, and the brain can then switch into conservation mode.

An overview led by Dantzer describes how immune cells produce inflammatory messengers that act on the brain and trigger sickness behaviour. If this activation persists, it can turn into depressive symptoms in susceptible people [Narrative Review]. The examples given there are infections, cancer and autoimmune diseases, and applying this to mould is a hypothesis. A meta-analysis led by Osimo with 5,166 patients and 5,083 controls found on average higher levels of CRP, interleukin-6 and TNF-alpha in depression [Meta-analysis]. These are case-control data without any statement about the direction or the origin of the inflammation.

A follow-up study in male mice found long-term memory deficits after toxin-free spores, and higher motivation in the water maze after toxic spores. On the elevated plus maze, a standard test for anxiety-like behaviour, it was again the animals given toxin-free spores that showed more anxiety-like behaviour [In vivo, mouse]. The memory findings are inconsistent, and anxiety-like behaviour in a mouse is not an anxiety disorder in a human.

Then the toxins themselves. In a study led by Islam, purified satratoxin G, a toxin from Stachybotrys, led to the loss of olfactory nerve cells in mice after being given into the nose, with inflammatory messengers in the nasal mucosa and olfactory bulb [In vivo, mouse]. In rhesus monkeys, the same toxin led to acute rhinitis and the death of olfactory nerve cells in a study led by Carey, with three animals per group and without looking at behaviour or mood [In vivo, primate]. A review led by Doi summarises that individual mycotoxins have neurotoxic potential in rodent models, with ochratoxin A, for example, acutely lowering dopamine in the striatum in an animal model [Mechanism Review, animal and cell data]. All of this comes from models with targeted dosing.

The German Environment Agency (Umweltbundesamt) takes a similar view: the mycotoxin concentrations measured indoors so far are so low that they do not trigger acute toxic effects. There are indications of immunomodulatory effects, and so far no findings on long-term exposure [Agency document]. Open here means open, in both directions. The AWMF guideline rates neuropsychological and neurotoxic effects as insufficiently supported by evidence and states that a link cannot be ruled out [Guideline].

Functional medicine additionally looks at mast cells and inflammatory messengers. A narrative review led by Ratnaseelan describes that mould and mycotoxins could influence the nervous system directly or via immune cells, especially through messengers from mast cells [Narrative Review]. That is a collection of hypotheses, not a systematic assessment.

Is black mould more dangerous for mental health?

Stachybotrys chartarum is often called black mould. In animal studies, its toxins damaged olfactory nerve cells. I have not found a human study linking black mould with depression or anxiety. The AWMF guideline criticises early papers on a black toxic mould syndrome for methodological weaknesses [Guideline].

And in Harding's mouse study, anxiety-like behaviour increased precisely with the toxin-free spores. Colour or proof of toxins are therefore not a good yardstick for deciding whether action should be taken. According to the AWMF guideline, relevant mould growth should be removed, regardless of whether mycotoxins have been formed or not [Guideline]. You can find the basics on these substances in Mycotoxins: the basics.

And now you know why I am cautious with sentences like "mould inflames the brain": they describe a hypothesis from animal models.

The well-established side: allergy, airways, sleep and mood

It is three o'clock at night. Your nose is blocked, your throat is scratchy, you turn over, again and again. The next day your patience is shorter and your worry is bigger.

The physical side has been well studied, and by a detour it also leads to mood.

The German AWMF guideline sees sufficient evidence for allergic respiratory diseases, allergic rhinitis, asthma, respiratory infections and rhinosinusitis. It rates what its English version calls mood disorders (in German Befindlichkeitsstörungen) as having limited evidence, meaning impairments of psychological, physical and social wellbeing, not psychiatric diagnoses [Guideline]. According to the guideline, such impairments of wellbeing can affect anyone with damp damage in their home, but they are not an acute health hazard.

The long version names three explanatory models for this, including a stress model. According to this, changes in wellbeing can include anxiety, depression, concentration problems and measurable reactions of blood pressure and hormones. It counts sleep disorders among the complaints that are repeatedly associated with damp damage in epidemiological studies [Guideline].

A review led by Mendell found consistent associations between dampness or mould and asthma, shortness of breath, cough, respiratory infections, bronchitis, allergic rhinitis and eczema, in people with and without allergies [Review of the epidemiological evidence].

And this is where a circle closes. A meta-analysis led by Lu with 51 studies found that allergic diseases went along with a higher risk of depression (relative risk 1.59), for asthma likewise 1.59, and for allergic rhinitis 1.57. In men the association was not significant (1.37), in women it was (1.65) [Meta-analysis, 51 studies]. A meta-analysis led by Rodrigues found higher odds of depression and anxiety in allergic rhinitis [Meta-analysis]. An umbrella review led by Xu covering 21 meta-analyses rated the association between allergic rhinitis and sleep disorders as highly suggestive (odds ratio 2.17), and asthma went along with depression (1.64) and anxiety (1.95). According to the authors, these associations do not mean causality [Umbrella Review].

How a mould allergy differs from a possible burden from mycotoxins is something I describe in Mould allergy or mycotoxins, and the role of the nose in Chronic sinusitis and mould.

And now you know why airways and sleep belong in the front row when it comes to mould and mental health, not in a footnote.

What you can do in practice

Perhaps you are now thinking: and what do I do tomorrow? A good start is usually smaller than it feels.

Tackling the cause of the dampness

The WHO names four indications of a damp problem: condensation on surfaces or in building components, visible mould, a perceived mouldy odour and a history of water damage or water leaking in [Guideline]. According to the German Environment Agency, visible mould growth with a known cause usually does not require any further measurements, and the area should be remediated promptly [Agency document]. That can save you detours and costs.

How to go about it in concrete terms is described in Mould in your home: what to do and in the practical guide for the first few weeks, and what remediation can achieve in Mould remediation, a realistic view.

Heating and airing, without blame

Heating and airing are part of prevention. But Brooks' review shows that people cut back on both out of worry about energy costs [Scoping Review]. Someone who is freezing to save money does not have a knowledge problem. That belongs in advice and support, not in an accusation.

Tenancy law: just a pointer

This is not legal advice. It makes sense to document the mould growth with dates and photos. Questions about notifying defects, rent reduction or who is responsible belong with a tenants' association, a consumer advice centre or a lawyer specialising in tenancy law.

In the Australian study, tenants depended on their relationship with the landlord, and lack of knowledge, costs and time slowed down remediation [Qualitative study]. Advice services exist for exactly this gap.

Taking the burden itself seriously

In the British household panel, a longer duration of housing problems went along with poorer mental health [Panel, longitudinal]. So an unresolved housing problem appears to be a factor in itself, and every step that gets the situation moving can count. The Shenassa study did not examine how the sense of control can be strengthened. It seems reasonable, though, that small actions can contribute to it: a photo, a letter, a call to an advice service, a conversation with someone who shares the load. None of these dries the wall overnight, but each can change the feeling of being at the mercy of your home.

Having physical symptoms assessed

Respiratory symptoms, allergies or asthma should be assessed by a doctor. The counselling pathway in the Deutsches Ärzteblatt starts with a medical history and examination and pays particular attention to a weakened immune system and atopy, meaning the tendency to develop allergies [Review, guideline-based]. Sleep problems lasting for weeks also belong in that conversation.

And now you know why the first step does not have to be perfect, just one that gives you back a bit of control.

The honest limit: mould does not explain depression on its own

Perhaps you are hoping that the heaviness will leave together with the mould. That hope is understandable. I don't want to take it away from you, only to put it on a foundation that holds.

The German National Disease Management Guideline Unipolar Depression describes depression with a vulnerability-stress model: biological and psychosocial factors interlock, and their weight can differ considerably from person to person [Guideline]. A stressful housing situation is one of several psychosocial factors in this model. It is not the illness.

Depression is a serious illness and deserves a careful diagnosis and its own treatment. For acute moderate depressive episodes, the guideline says psychotherapy or medication should be offered as equal options (recommendation 5-8, strong recommendation). For acute severe episodes, a combination of both should be recommended, and if people decline the combination, both should be offered as equal options on their own (recommendations 5-13 and 5-14, each a strong recommendation) [Guideline]. Anxiety disorders can also be treated well. For panic disorder and agoraphobia, the German S3 guideline recommends offering psychotherapy and pharmacotherapy, taking into account the preference of informed patients, and cognitive behavioural therapy should be offered for panic disorder and generalised anxiety disorder (grade of recommendation A in each case, version 2 from 2021) [Guideline]. None of these guidelines mentions mould.

And an honest gap: I have not found a study showing an improvement in depression or anxiety disorder after mould remediation. There are only indirect indications.

In the GoWell study from disadvantaged neighbourhoods of Glasgow with 1,933 residents, work on the building envelope went along with a small improvement in mental health after one to two years (plus 1.84 points on the SF-12), and finding a job with a markedly larger difference (plus 5.50) [Quasi-experimental, longitudinal]. The home matters, but it is never the only lever.

Treatment itself is the subject of Treating depression holistically, while here the focus is only on the environmental factor. The distinction between burnout and depression is described in Burnout or depression.

My view: guideline and functional perspective considered together

On this topic, guidelines and functional medicine are closer to each other than it often sounds online. Both agree that the cause of the dampness needs to be tackled, that airways and sleep should be taken seriously and that impairments of wellbeing must not be dismissed.

The difference lies in the biological pathway. The AWMF guideline considers neuropsychological effects to be insufficiently supported by evidence and explains impairments of wellbeing, for example in response to odours, through conditioning, attribution or stress, not through toxicological mechanisms. Attribution does not mean imagination, but that knowledge, worry and experience help determine how strongly a burden is felt. Functional medicine additionally looks at immune activation and mast cells, so far supported mainly by animal data. Given this evidence, the restraint of the guideline is very understandable. How conventional medicine classifies mould can be read in Mould and conventional medicine.

That is why, for me, the home belongs in every holistic medical history for anxiety or depression. As one factor among others, and never as a substitute for psychotherapy or psychiatric treatment.

If you would like to take a calm look at your home, airways, sleep and mood together: below this article you will find the option to book an appointment. This does not replace ongoing psychotherapeutic or psychiatric treatment.

And now you know why, when it comes to mould and mental health, I take both seriously: your home and you.

Frequently asked questions about mould and mental health

Where this article connects with other topics

These articles lead on from here.