Millions of people in the United States and around the world experience some degree of smell loss or dysfunction of their sense of smell. This can have a severe impact on individuals’ well-being, as a new study demonstrates.

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People whose sense of smell becomes compromised experience difficulties in various aspects of their lives, new research reveals.

According to data from the National Institute on Deafness and Other Communication Disorders, almost 1 in 4 people over the age of 40 in the U.S. experience a change in their sense of smell.

This change could be partial or total smell loss, smell distortion, or even phantom smells, and these issues can result from a range of factors.

“There are many causes — from infections and injury to neurological diseases such as Alzheimer’s and as a side effect of some medications,” says Prof. Carl Philpott, from the University of East Anglia’s Norwich Medical School, in the United Kingdom.

Recently, Prof. Philpott and colleagues set out to understand just how life changing the loss of smell can be. As the team’s study revealed, such a change can have a profound impact on people’s well-being.

The investigators report their findings in a study paper that appears in the journal Clinical Otolaryngology.

The best-known effect of smell loss is the impact on how well the person is able to taste, since smell and taste are closely interlinked.

“Most patients suffer a loss of flavor perception, which can affect appetite and can be made even worse if distortions in their sense of smell also coexist,” says Prof. Philpott.

Yet this is not the only way in which impairment to smell, one of evolution’s earliest senses, affects a person’s life.

“Previous research has shown that people who have lost their sense of smell also report high rates of depression, anxiety, isolation, and relationship difficulties,” Prof. Philipott notes.

“We wanted to find out more about how a loss of smell affects people.”

To do this, the team recruited 71 participants aged 31–80 who were affected by smell disorders and who had received support from The Smell & Taste Clinic at the James Paget University Hospital, in Gorleston-On-Sea.

The research team also collaborated with Fifth Sense, a U.K.-based charity for people living with smell and taste disorders.

The participants described their experiences in their own words. After reading and analyzing these accounts, the researchers found that people with smell disorders can experience a range of issues that affect day-to-day life, including relationships.

The effects involved a negative impact on mental and emotional health, social isolation, and increased risks to other aspects of physical health, as well as financial difficulties associated with receiving the necessary support.

“One really big problem [that participants reported],” says Prof. Philipott, “was around hazard perception — not being able to smell food that had gone off or not being able to smell gas or smoke.”

“This had resulted in serious near misses for some,” he emphasizes, calling smell “a lifesaving sense.”

The researcher also spoke of this sense’s “life enhancing” qualities, which means that, when smell becomes impaired, a person’s overall enjoyment of life may diminish.

“A large number of the participants no longer enjoyed eating, and some had lost appetite and weight,” observes Prof. Philipott.

Also, the team found that smell loss could affect the content of the diet. Some participants “were eating more food with low nutritional value that was high in fat, salt, and sugar — and had consequently gained weight,” the researcher adds.

Many study participants reported that their loss of smell meant that they could no longer participate in social activities, such as cooking for friends and family, which made them feel isolated.

“Participants had lost interest in preparing food, and some said they were too embarrassed to serve dishes to family and friends, which had an impact on their social lives,” explains Prof. Philipott.

And, since people have cherished memories of different smells — a perfume associated with a loved one, for instance, or the smell of freshly cut grass in the garden of a childhood home — some participants felt that they had lost important connections with people and places.

“The inability to link smells to happy memories was also a problem. Bonfire night, Christmas smells, perfumes and people — all gone. Smells link us to people, places, and emotional experiences. And people who have lost their sense of smell miss out on all those memories that smell can evoke,” he notes.

Smell loss also led to feelings of anxiety and inadequacy, since many participants were worried about not being able to sense their own body odor, for instance.

“We found that personal hygiene was a big cause for anxiety and embarrassment, because the participants couldn’t smell themselves,” says Prof. Philipott.

Moreover, the researcher notes, “Parents of young children couldn’t tell when their nappies needed changing, and this led to feelings of failure.”

“One mother,” he adds, “found it difficult bonding with her new baby because she couldn’t smell him.”

Perhaps unsurprisingly, for many people, these obstacles lead to difficulty in maintaining the quality of relationships.

The researchers emphasize that the problems linked with loss of smell significantly affected participants’ mental and emotional health, leading to anger, depression, anxiety, frustration, and a decrease in confidence.

People who took part in the study also reported frustration with the fact that many healthcare practitioners do not understand the full impact of smell disorders.

“The participants described a lot of negative and unhelpful interactions with healthcare professionals,” says Prof. Philpott.

“Those that did manage to get help and support were very pleased — even if nothing could be done about their condition, they were very grateful for advice and understanding,” he notes.

Duncan Boak — the founder and chair of Fifth Sense — who did not contribute to this study, also emphasizes that smell loss “can have a huge impact on people’s quality of life in many ways, as this research demonstrates.”

However, he hopes that, thanks to this and future studies, people who are affected by smell disorders will start to receive better support.

“The results of this study will be a big help in our ongoing work to improve the lives of those affected by anosmia,” he says.