Consider any instant in your life, from the mundanities of your daily grind to those special moments — the smell of a freshly brewed cup of coffee; the taste of a dish that takes you straight back to childhood; your favourite track suddenly playing on the radio; the feel of your child’s hand in your own.

These snapshots represent the merging of our external and internal worlds — the coming together of our memories, emotions, histories and desires, and our environment.

And central to all these are our senses — vision, hearing, taste, smell and touch. 

These senses are our windows on reality; they are how we absorb the outside world and begin to understand what’s going on in it.

We are isolated, cut off and adrift without them. Losing any one of them — becoming blind or deaf, for example — can be both disabling and traumatic. 

Our senses can go completely sanitized, and they may also become lost. This could lead us to strange, confusing, or even terrifying places. 

As well as being one-third of television¿s celebrated Seventies comedy trio, The Goodies, Oddie, now 80, is Britain¿s best-known birdwatcher

As well as being one-third of television’s celebrated Seventies comedy trio, The Goodies, Oddie, now 80, is Britain’s best-known birdwatcher

Hearing the stories of patients I’ve treated as a neurologist over the past 20 years, or individuals from other walks of life — those with a diminishment or amplification of one of their senses — I am struck by the fragility of our senses, and how our grip on reality is so reliant on the integrity of our nervous systems. 

Their experiences have raised questions about the reality of reality as well as what it means to be human.

Standing in the rain at a London park, my surroundings are filled with birdboxes. Bill Oddie is explaining the arrangement to attract birds while telling me stories about strange and illusive music that haunts his mind every day.

As well as being one-third of television’s celebrated Seventies comedy trio, The Goodies, Oddie, now 80, is Britain’s best-known birdwatcher.

He realized five years ago that he couldn’t hear the higher-pitched call of meadow pipits.

With age, Oddie’s hearing has begun to decline. Oddie doesn’t hear shrill birdongs, but something entirely different. Something that isn’t there.

The idea was born three years ago. ‘I thought someone was playing a record or radio next door, but couldn’t locate which wall it was coming through,’ he says.

Oddie introduced me to Oddie through charity. Oddie recalls the weeks he spent moving about different rooms in search of the source.

Eventually he realised it was all a hallucination, an auditory ‘mirage’ that follows him almost everywhere. There’s nearly always a trumpet playing a high note — ‘one of the sounds I really dislike,’ Oddie says. 

‘There’s almost always a male voice or a small male-voice choir; very occasionally a female voice. It sounds like someone playing a radio, but it’s an old-fashioned style.’

Oddie breaks into song and sings a few bars from All The Nice Girls Love A Sailor. He goes on to describe a jukebox selection — ‘Only, I can’t choose them!’ — singing snatches of Daisy, Daisy, Blaydon Races, Rule Britannia and the national anthem.

He prefers jazz over jazz-rock. ‘I’m getting more annoyed with the songs. I have been known to say “Shut up!”’ he laughs. ‘I haven’t lost a sense of humour about it. I would if it was driving me nuts.’

Music hallucinations may be experienced in patients with neurologic diseases or mental disorders like dementia, seizures, or other neurological conditions. However they can also happen in completely healthy individuals.

Oddie is certain that the songs he hears and sings are illusions. He is still firmly grounded in reality. This isn’t the symptom of a psychiatric disease.

Tinnitus is when a sound such as singing or trumpet playing comes from an outside source. Oddie is capable of hearing sounds without external stimuli. But rather than hearing a ringing, it’s more complex, nuanced, melodic.

A recent survey of hearing patients found that one-in-20 reported hearing hallucinatory music, although it is rare.

Oddie’s musical experiences are rather typical, with people describing big-band music, church choral music, trumpets, occasionally even country music. Many people report hearing shorter, more fragmented melodies as the time goes by.

Five years ago, he realised he could no longer hear higher-pitched calls from bird species such as the meadow pipit. His hearing is deteriorating with age. And instead of shrill birdsong, Oddie hears something else entirely. Something that isn¿t there

He realized five years ago that he couldn’t hear the higher-pitched call of meadow pipits. As he gets older, his hearing loss is worsening. Oddie now hears more than just shrill birdong. Something that isn’t there

Experts think that this is because the brain doesn’t have the ability to completely recreate the environment each day. It instead predicts the best explanation of what we see.

This balance allows our senses to function perfectly when there are both outside-in and inside-out information. But when the system is out-of-kilter, when either the inputs are too limited, as in Oddie’s hearing loss, or when the outputs of our brain are too intense, such as in psychosis or under the influence of psychedelic drugs, this results in hallucinations or delusions.

Even though they are intended to help us understand the world better, these mechanisms can actually confuse our perception of reality rather than helping to clarify it.

Oddie was in good health and I reached out to him recently. ‘The male-voice choir are still going strong. The lyrics are less clear and the melodies less familiar, but the overall style is consistent,’ he wrote in an email.

‘I remain both surprised and narked that what I hear is never like music I have enjoyed. The repertoire is being selected by who or what? Need a new DJ for my cranials. Oh no, not Land of Hope and Glory again.’

Some people may find patriotic songs entertaining, but no one wants to live with the smell and taste of rotting flesh and sewage.

Joanne feels bitter that people ignore her condition, which has plagued her for the last five years. She is bitter, too, about the condition’s all-pervading effects, which have made her world stink.

‘I’d sit with a handkerchief over my nose, trying to stop any smells, to stop breathing really. I’d breathe through my mouth instead of my nose to stop having to smell that smell,’ she says. ‘People would make jokes of it, laugh at me.’

Joanne was just 40 years old when she got what looked like a mild head cold. The sinusitis remained for many weeks, and eventually led to chronic pain. The problem was finally solved by a course of antibiotics.

A few weeks later, ‘I started to notice a foul, putrid smell’, she says when we meet. This stench of rotting flesh or sewage became all-pervasive, even permeating her food: ‘Everything tasted chemical or as if mouldy or rotten.’

The stench was amplified by certain odours. ‘Cooked food, coffee, cigarette smoke, even fabric softener or perfumes, all intensified the putrid smell 20-fold,’ says Joanne.

Going to work, surrounded by colleagues’ perfume and aftershave, became intolerable. Her illness lasted for several months. Families became difficult. Sunday lunch with her partner and her sister’s family became overwhelming. ‘I just wanted to sleep all the time. That was my only escape,’ she says.

She was also distressed by the lack of support and understanding. ‘My GP hadn’t heard of it at all,’ Joanne recalls. She received various medications and nasal sprays, but nothing worked.

Google provided some help. Google gave the condition parosmia a name.

The simple act of inhaling is an act of vigilance — sampling the external world, detecting danger, seeking food, family, a potential mate. Our brain only reaches outside our bodies through the nose, which is the point at which our central nervous systems meets the outside world.

The neurons of our senses are also protected. They can be encased like our eyes and ears. The linings in our nose, which are responsible for smell, extend into the outer space and grasp at air.

The exposed neurons can be at risk from injury, trauma or inflammation. A simple cold, inflammation of the nasal passages, a blow to the nose — all may result in killing the neurons.

The severity of the damage to neurons will determine whether there is a loss of sense of smell.

But it may also cause an alteration in smell, like Joanne’s. It is common to describe the smell disturbance as rotten, foul and sewage-like. Joanne is an excellent example of a classic case.

Another important characteristic of parosmia (and other disorders of smell and taste) is depression. This condition affects more than half of the patients. The condition massively affected Joanne’s mood. ‘You just can’t even think about living a life when you’re constantly smelling a putrid smell,’ she says.

Joanne received her diagnosis and was informed that there wasn’t a cure. She was able to find an ear, nose, and throat surgeon who specialized in the treatment of smell disorders. Theophylline, an asthma drug, was offered as an experimental treatment.

It’s believed that this drug may boost factors that drive olfactory neurons to replicate, accelerating the cells’ replacement. If the underlying cause of Joanne’s parosmia is the loss or damage to a sub-group of these neurons, then promoting regrowth would help.

Joanne tells me that ‘within two weeks the drug suppressed that putrid smell’. Also, she ended up using gabapentin. It was originally designed to treat epilepsy. However, it can be used in various neurological situations to reduce neuronal activity.

Since then, she has been free from both prescriptions for approximately a year. Although she continues to improve, she has begun a smell retraining treatment. She holds several oils of essential oils underneath her nose twice daily. It is her goal to get the nerve system to sense again.

‘I’m making progress,’ she says. ‘When I was first diagnosed, they said that if my sense of smell didn’t come back within six months, it probably never would.’

It’s taken her four years to get to where she is now, ‘about 80 per cent better’.

‘I don’t smell a putrid smell any more,’ she says. ‘I don’t have normal smell, though. I still don’t like a lot of perfumes.’

It was a taste, rather than a smell, that marked the beginning of Alison’s bizarre troubles. Her sensory world was turned upside-down by her raving desire for an exotic fish she had tasted on holiday. ‘I ate the same thing every evening on our fortnight’s stay — a locally caught coral trout.’

Alison tells me all about the resort in Fiji that is so stunning, she and her husband would go there every year with their children.

However, in 2013, several days into one of their trips, Alison developed a strange sensation — when she walked across the tiles, her feet felt ‘oddly sensitive’.

It was her hands that she had to wash the next year in Fiji. ‘When washing them, it felt like hot was cold and cold was hot. After 48 hours it was difficult for me to even hold cold water. It felt like my fingers were burning.’

It wasn’t just in her hands. ‘If I put the water to my lips, it felt like my lips were burning. It felt as though my feet were being burned by the hot water when I tried to get into the pool. The pain was so bad it would make me cry, and then the tears felt like they were burning my face.’

Her family was terrified. They managed to speak to a specialist who suggested a possible explanation — food poisoning caused by her nightly fish dinner.

The poisoning was not caused by the fish, but the food it had eaten. Ciguatoxin is a toxin produced by plankton that can be found in coral reefs.

Ciguatoxin, unlike other types of food poisonings, is not affected by freezing or cooking. This helps to explain why it’s the commonest form of fish poisoning, with up to 50,000 cases worldwide every year.

After being ingested it quickly spreads throughout the body. You may experience typical symptoms of food poisoning, such as gastrointestinal upset. But damage to the peripheral nerves causes ciguatoxin poisoning’s most striking symptom, ‘hot-cold reversal’. Alison was sent home with medication to ease her discomfort. However, the temperature inversion lasted for six more months.

Two years later, flare-ups continued. They were triggered either by stress or illness. Alison continues to live in the shadows of the coral trout six years after her diagnosis. She occasionally suffers symptoms from stress.

Before anyone who doesn’t live or holiday in these exotic locations sits too comfortably, they should heed a warning from Matthew Kiernan, Alison’s neurologist in Sydney. Ciguatoxin could be harming people, he believes.

‘Fish that are caught in the Caribbean can easily be on a restaurant table in London that evening. Similarly, fish in the Asia-Pacific are distributed through efficient networks,’ he says.

In Alison’s case, a single molecule, derived from plankton, scrambled her senses to such a degree that the rules of physics appear upended; that hot is cold and cold is hot.

Perhaps this is the best example of how you can get deceived by your nervous system, which in turn affects your ability to comprehend the world around us.

Professor Guy Leschziner is a neurologist at Guy’s and St Thomas’ Hospitals in London.

Extracted from The Man Who Tasted Words by Dr Guy Leschziner, published by Simon & Schuster, £16.99. © Dr Guy Leschziner 2022. To order a copy for £15.29, go to or call 020 3176 2937. Free UK delivery on orders over £20. This offer is valid through February 9, 2022.