A fairly strong knock to the head can do more than give you a headache. It can also lead to a temporary loss of sense of smell.

The good news here is that losing your sense of smell for the time being tells you the concussion that hit you isn’t to be dismissed. And that it’s time to see a doctor. A small study from the University of Montreal found that even a mild concussion can temporarily affect a person’s sense of smell. It might also trigger longer-term anxiety problems.

The University of Montreal-led study was recently published online in the journal, Brain Injury.

What’s new about the findings is these problems were long known to stem from major concussions that also manifest in milder concussions caused by accidents such as falling off a bike with a helmet on or slipping and hitting your head.

"A lot of people will suffer a mild concussion at some point in their life, so realizing they have trouble smelling is the first step to telling their doctor about it," said lead author, Fanny Lecuyer Giguere, who did the research as part of her doctoral thesis in neuropsychology at the University of Montreal.

The small study included 20 people suffering from minor concussions. There was also a control group of 22 people who had broken limbs but no concussions.

Within 24 hours of their injury, just over half of patients with mild concussions had a reduced sense of smell. This compared to the 5 percent of the patients with broken bones, according to the study

A year later, the concussion patients' sense of smell had returned to normal. Most regained their former state within six months. On the other hand, 65 percent of these people said their rate of anxiety became considerably higher than the control group, noted the study.

Symptoms of anxiety included worry, difficulty in relaxing and sudden attacks of panic.

"It's important that patients report any loss of smell, because it's not something their general practitioner or emergency room physician normally asks about," said Giguere.

Consultation might result in closer follow-up to see if the loss of smell and anxiety persist. It could help determine the severity of the concussion, according to Giguere.

Giguere also said that doctors should tell patients with minor concussions to report loss of smell or anxiety in the weeks following their injury. She said it’s a question of raising awareness: The more people are told to watch for signs of olfactory loss (or loss of smell) and anxiety, the easier it will be for doctors to respond.

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Women Can Tell If You Smell Good, Even If They Can’t Smell YouThe same International Journal of Cosmetic Science study found that women who watched videos of the men in the study rated the men wearing scented deodorant as more confident and attractive. Getty Images