What sense of smell – odors – tells us about mental illness?

By David Joel Miller MS, Licensed Therapist & Licensed Counselor.

Sense of smell.
Photo courtesy of pixabay.

Is there a connection between the sense of smell and mental illness?

There is a body of research that tells us that there is a connection between the sense of smell, your ability to recognize and identify odors, and the chance you have or will develop a mental illness. There are also cases of olfactory hallucinations; smelling things that everyone else is sure is not there.

While this research suggests some connections, to me the articles I have read are short of conclusive.

An altered sense of smell has been linked to disorders as divergent as Schizophrenia, Bipolar disorder, autism, and eating and feeding disorders.

Smelling it does not mean you can identify the smell.

One thing we do know is that the ability to identify an odor is not the same thing as the ability to detect one. People are more likely to like a smell they can identify and unknown smells are more likely to be considered unpleasant. Memory and its connection to smells are important for many reasons.

Smells trigger memories.

This is significant because smells are powerful memory cures. People who have a poor ability to notice smells or to remember them are at a disadvantage in remembering things that might be associated with those smells.

Schizophrenia and odors.

The disorder most cited as having olfactory (odor or smell) impairment is Schizophrenia. More interesting yet is the repeated observation that males with schizophrenia are far more likely to have olfactory disruption than females (Nguyen et al, 2010.) These males with schizophrenia had disruption of odor identification, memory, odor detection abilities, and poor odor discrimination, the ability to tell one smell from another.

Females in these studies rather than not being able to recognize or identify smells were more likely to smell foul or unpleasant things that were in fact not detectable to others. The conclusion was that women have more olfactory hallucinations and men more loss of ability to smell.

Schizophrenia is characterized by negative symptoms, which are the loss of some abilities others have, as well as positive symptoms such as hallucinations. Someone with schizophrenia will likely have or experience social withdrawal, attention problems, difficulty making decisions, and perceptual problems.

People with schizophrenia also have high rates of olfactory identification problems, discrimination of smells, olfactory memory, and olfactory detection errors, principally in males. Poor olfactory discrimination is also found in close relatives of people who have been diagnosed with schizophrenia even when those relatives have not received the diagnosis themselves.

Olfactory identification problems do not appear to be found in people with Bipolar disorder, Major depressive disorder, other related psychosis, or anorexia nervosa.

Alzheimer’s, and Parkinson’s diseases and smells.

Olfactory hallucinations and discrimination deficits are seen in those with Alzheimer’s, and Parkinson’s diseases in addition to Schizophrenia.

One researcher reports that people with Bipolar Disorder have some olfactory impairment but that they are less bothered by unpleasant smells that those people who have Schizophrenia (Cummings et al., 2010.)

Autism and odors.

In Autism olfactory identification is reported as impaired. Individuals who had been diagnosed with Autism preferred Lemon and Orange smells, to lavender. They disliked most other strong smells. In Autism strong smells are linked to perceptions of taste and result in high rates of food refusal and selectivity (Hrdlicka et al., 2010.)

Olfactory hallucinations.

One condition of note is olfactory hallucinations. Some patients reported a foul-smelling order coming from themselves. This odor was not detected by staff. This olfactory hallucination is referred to as Reference Syndrome and was reported in patients with temporal lobe epilepsy. Other olfactory hallucinations have been reported in clients with substance-induced Psychotic Disorder, Hypomania with Alcohol dependence combined with hypomania (Luckhaus et al., 2003.)

There does not appear to be any connection between depression and olfactory dysfunction (Scinska et al., 2008.)

Migraines and odors.

Olfactory dysregulation has also been linked to people who have frequent migraines, with over 45% of people experiencing migraines reporting odors are triggers for those migraines. In migraine suffers, almost 25% had a fear of a particular odor, and an equal number reported taste abnormalities when having a migraine episode. MRI’s showed that women were eight times more likely to have brain activation from odors. This makes one wonder if many of the issues with odor detection, memory, and discrimination are more linked to gender than to a particular psychiatric diagnosis.

Other studies have reported significant episodes of visual hallucinations during migraine attacks and make the point that visual and auditory hallucinations are so pronounced and readily identifiable most people are not asked about and do not report either olfactory (smells) or gustatory (taste) hallucinations.

In people with schizophrenia, 75% reported auditory hallucinations, 37% reported somatic hallucinations while olfactory hallucinations were reported by 18% of the patients which is slightly more than the 14% who reported visual hallucinations. Despite being so common, few clients report olfactory hallucinations and clinicians are not generally looking for them.

While people with schizophrenia may experience hallucinations in all modalities, providers frequently stop asking about hallucinations after the first or second reported hallucinations.

Stress and hallucinations.

Researchers find that people who report being under “stress” are more likely to have experienced olfactory hallucinations and one study concludes that stress may lower the threshold for hallucinations of any type.

Because the major part of the olfactory sensing part of the brain is on one side of the brain researchers have suggested that there may be a difference in the way in which left-handed and right-handed people experience olfactory hallucinations.

While olfactory hallucinations are readily identifiable in people who have migraines they are less identifiable but more likely to be described as unpleasant in those with epilepsy.

While we still can’t use olfactory or gustatory hallucinations or dysfunction as makers for a particular mental illness, we know abnormalities in the sense of smell and taste may be factors in the development of a mental or emotional problem.

Have you experienced an alteration in your sense of smell or taste and no medical reason has been found? Care to share?

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18 thoughts on “What sense of smell – odors – tells us about mental illness?

  1. My landlord who is the son of a severely damaged WW2 Dutch hero, is slowly starting to deteriorate with all sorts of odd displays. Having a “phantom odour” is something that has reared its head periodically with him. I get blamed for it of course. Along with conspiracy theories and a number of fears and phobias, he loves to keep me on the edge, being his tenant in his basement suite and being from Austrian decent he knows what buttons to push. We both have so much in common because my father was a Concentration Camp survivor (Mauthausen), but I have different coping mechanisms, both of us had tyrants for father’s but so far I just have maybe an excess of anxiety that I’m trying to keep in check but not madness; not yet anyway.


    • Thanks for your comment. Sounds like a difficult situation but one your managing to cope with. Ideally, both of you would benefit from seeing a professional. Short of that, I hope you have a support system of people you can talk to.


  2. I was diagnosed with schizoaffective disorder about 5 years ago and have been on medication ever since. Generally I have auditory hallucinations (typically hearing voices) and occasionally I have visual ones but I have never had olfactory or tactile hallucinations. A couple days ago, I could smell cigarette smoke while I was sitting in my living room. I don’t have any neighbors so the only explanation would be that someone was hanging around outside my house without me knowing, or that I was hallucinating. Is it possible for someone who usually has certain types of hallucinations to suddenly develop a new type of hallucination? Later that same night, I thought I heard someone on my porch and called the police, who came by and didn’t see anything. I really don’t know if something is going on that I should be concerned about or if my psychosis is coming back. This morning, my therapist recommended setting up booby traps, which I have put in place. Contemplating taking my backup medicine (Haldol) but I’m just not sure if it’s me or if it’s real.


    • I think, given your diagnosis, is possible for you to experience other kinds of hallucinations. You may have had mild olfactory hallucinations that went unnoticed in the past. Of course, if someone is smoking around you that it’s not a hallucination. Before going back on your medication I would check with your prescribing physician. They may want to try you on a different medication. One of the characteristics of the disorder you mention is the way your symptoms can change over time. Hope this helps.


  3. I was diagnosed with schizoid personality disorder a year ago–all the negative symptoms of schizophrenia. It explains a lot about my lifelong inability to connect to the world and have “normal” social interactions. Interestingly, I have always been able to “pass” socially, just always a little strange and outside social acceptability. I lost my sense of smell in 2008 when I was 43 years old. There was no apparent cause. I have smelled nothing since 2008. I’ve had 2 MRIs to check for tumors, and I’ve had an ENT check for polyps. Nothing. It was also about that time that my SPD became so bad that I eventually sought the professional help that led to the diagnosis a year ago. Do you think the anosmia and SPD are connected? Who can I talk to about this? The psychologist who diagnosed me said therapy for SPD would probably be futile since I don’t socialize, talk, open-up. And he’s right, of course.


    • I am not sure who you would consult about this. Possibly a neurologist. Sounds like an interesting case for someone who does research, possibly at one of the larger universities. I suspect it’s very likely your disorder and you change in sense of smell are connected. Not sure I agree that therapy wouldn’t benefit you. Personality disorders can be treated using psychotherapy. What therapy would most help you do is learn more skills to cope with other people despite your condition. I think too many people with disabilities get written off because we think we can cure them of that disability. Sometimes what counseling can do is help them learn to live the best life possible despite that disability.I read that you don’t socialize, talk, or open up, what you need to look at is does having this personality disorder interfere with parts of your life and would you like to change those connections. Do you work? Would you like to? Are you able to go places and do things that you enjoy? Take a look at your life and there may be things you would like to be more able to do. If so counseling or life coaching probably can help you.


  4. My son turned 25 and had severe migraines we did MRI and nothing showed up now he is 30 and at the time and now he believes gluten is in the air causing him extreme harm so he feels if he is in a room with gluten he will get migraines he moved away and isolated himself from the family and can’t work and lived homeless for 3 years even not attending shelters so living on the street I and his family wanted desperate to help him. No medications will he take because they have gluten filler in them so he won’t go to a doctor. We finally found him and have convinced him to get off the street and are keeping him safe. Now we don’t know how to get him help…please contact me and give is a direction for help. Pattiweiland57@hotmail.com. Please help him.


    • Hi Patty. This is a very difficult situation which many families face. Since he is and adult you can’t make him do much of anything. This sounds very much like a fixed delusion. I doubt there is gluten in all the places he thinks there is. There are liquid or injectable medication that would not contain gluten but he has to be willing to talk to a doctor about this. Try to get him to see a medical doctor and look for other possible causes of the headaches. I would also try to get him to see a counselor, either through your local mental health or privately if he is covered by insurance. You also need to seek local support for yourself, as you deal with this problem. I would suggest you look for a local chapter of NAMI or visit their website. Hope this helps.


  5. For years I have experienced difficulty smelling. Sometimes I can’t even smell popcorn popping in a microwave. Other times, I can smell more normally. But a couple hrs ago I had an olfactory hallucination, I think. I suddenly smelled an overpowering smell like turpentine or some sort of strong chemical. It was so strong that it seemed toxic level. My seventeen yr old granddaughter didn’t smell anything. It was coming from my left. Then after a few minutes it suddenly disappeared , like instantly…..I do have MS, but never experienced this before.


    • I have to wonder if abnormalities in your sense of smell are not connected to your MS. The National Multiple Sclerosis Society http://www.nationalmssociety.org/What-is-MS describes MS as a disease which damages the nervous system. Some common symptoms include cognitive changes, vision and, hearing loss. If cells in the brain are being damaged I would not be surprised that people might experience changes in their sense of smell. I have read reports of people using methamphetamine who subsequently developed MS. One theory for this was that drugs might cause a breakdown in the insulation of nerve cells, in effect causing them short out. I think this is something you want to ask your doctor about. Possibly do a search of medical literature. The connection between sense of smell and mental health issues probably needs a lot more research.
      Thanks for contacting me. I’ve had the blog set to auto pilot, publishing prescheduled posts while I’m away, so it’s taken me a while to get back responding to some comments and questions.


  6. During an extremely stressful time in my life I experienced a psychotic break that lasted about 3 days. A very foul smell was the first thing I noticed and it became central to my paranoid delusions. I became convinced that the hotel staff was stuffing dead rats in the vent system of my hotel room (a smell I was familiar with as a mouse had died in the heating duct in my childhood home, creating a foul odour for days) the smell was also present in my friends room, even though everyone assured me they could not smell it, I became convinced we were being targeted. Auditory hallucinations, confusion and sleeplessness were also present. I was later diagnosed with major depression.
    My son has since been diagnosed with BP type 1 with psychotic features. I have since questioned whether I may in fact be somewhere on the BP spectrum myself rather than MDD. Very scary ordeal.


    • Most people will receive a diagnosis of bipolar disorder, suffered from depression for a long time before being recognized as having bipolar disorder. The main difference between the two issue whether or not you have ever had an episode of mania or hypomania. This is something you might want to talk to a therapist about.
      Thanks for contacting me. I’ve had the blog set to auto pilot, publishing prescheduled posts while I’m away, so it’s taken me a while to get back responding to some comments and questions.

      Liked by 1 person

  7. Fascinating article. I knew a woman who had a psychotic breakdown in the early ’50’s – when there was so little science on such topics. I was a child who was a family member. At her total. breakdown episode before being hospitalized, she exhibited an ‘insanely’ heightened ability to detect the presence of another family member by ‘smelling’ him, from regions distanced from her physical location, relative to hers at that moment. The woman had no cognitive reason to logically think that person was anywhere near her. He was, unbeknownst to her, separated from her by a wall.
    I never thought much of this until 60+Years later coming across a man, in his -60’s who unremittingly asserts that he detects odors thar no one else does in the residence of a woman-tenant of his, that no one else experiences. He is ‘serious’, about it, not grandstanding for an economic edge. It is intriguing.

    Liked by 1 person

    • I would agree it’s intriguing. We probably need more research into olfactory functioning and its connection to mental health.
      Thanks for contacting me. I’ve had the blog set to auto pilot, publishing pre-scheduled posts while I’m away, so it’s taken me a while to get back responding to some comments and questions.


  8. Pingback: What are the six kinds of hallucinations? | counselorssoapbox

  9. Pingback: Sound & Smell Affect Your Learning and Productivity - |

  10. Very interesting David because I have the strongest nose anyone has ever known. I have proven I can smell if a Mounds candy bar was unwrapped in a closed room within the last 30 minutes! I can also detect if bug poisen has been used around my work site within the last 48 hours. I admit to a touch of social animosity by occassionally tossing work bathroom air freshner cans into the trash if they contain a mixture of chemicals that I find not only offensive, but dangerous since I’ve felt my airway constricting (Lysol being the worst:) Actually, I have always been hyperactive (not ADD), so I suppose this hyper sense of smell is just part of this wonderful trait. I know I’m not the only one avoiding the cleaning product isle in the supermarket. Anyways, interesting stuff.


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