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MS research update - How MS can affect the sense of smell - 28 December 2012

Our sense of smell is really important to us. It warns us about dangers such as smoke or harmful chemicals. It gives us pleasure – a rose would not be as beautiful without its smell. It helps us to appreciate the flavours of food and drink (80% of the flavour of food comes from the smell).

Also, many smells are linked to important memories and those memories get recalled, often very strongly, when we smell a particular scent. This is a reminder that the sense of smell is not just about what happens in the nose. There are important nerve pathways in the brain which are involved in interpreting what the smell is and what it means (for example, danger or dinner?).

How this study was carried out

Previous studies have reported that the sense of smell can be affected in MS. This study looked at what aspects were affected.

50 people with either relapsing remitting MS or secondary progressive MS took part. Information was collected on their medical history, the characteristics of their MS, any depression, level of disability and the number of lesions seen on an MRI scan.

Well known tests for the sense of smell, which use Sniffin Sticks®, were carried out. Each Sniffin Stick is a bit like a pen and contains a different concentration of the smell being tested.

In a typical test, someone is blindfolded and given three pens, only one of which has an odor. The person has to say which pen they can smell or if none of them have a smell. If they can't correctly identify which one has the smell, they are given a new set but containing a pen with a higher concentration of the odorant. This is repeated until the researcher is sure at what concentration the person can detect that particular smell.

The sticks can also be used to work out how well someone can tell the difference between smells. In this test, they are given three pens and asked to identify which one has a different smell from the other two. This is repeated another five times with pens carrying different smells.

What was found

The researchers found that the aspect of smelling that was most affected by MS was the threshold concentration, when someone could first detect the smell. 40% of people in the study had anosmia which is the medical term for loss of the sense of smell. Those with a greater disability also had difficulty identifying what a particular smell was.

What does it mean?

The researchers concluded that several aspects of the sense of smell were affected. In particular, those which required more thought, such as identifying a smell and telling the difference between several smells.

Rolet A, Magnin E, Millot JL, et al.
Olfactory dysfunction in multiple sclerosis: evidence of a decrease in different aspects of olfactory function.
Eur Neurol. 2012 Dec 19;69(3):166-170. [Epub ahead of print]
abstract

More about the sense of smell

More general information about the sense of smell is available in the Science section of the BBC web site. There is also an animation showing how the sense of smell works (click on the play button to advance to the next part of the sequence).

You can read more about the tests which use Sniffin Sticks ® here.

If you think that your sense of smell may be affected, NHS Choices has some suggestions on safety measures you might like to take. They are reproduced below.

It's recommended that you:

  • install smoke alarms in all areas of the home, especially in the kitchen and near the fireplace
  • change from natural gas appliances to electric
  • clearly mark expiry dates on food and mark leftovers with dates so that you know when to throw them away
  • carefully read warning labels on products such as bathroom and kitchen cleaners and insecticides, to be aware of potent chemicals

More about cognitive difficulties

Cognitive difficulties are problems with thinking such as with memory, attention span or concentration. About half of all people with multiple sclerosis have some cognitive problems at some time. You can read more in the A to Z of MS. 

StayingSmart is a website for people who would like to know more about managing cognitive problems. It contains examples of common problems such as:

  • I forget where I have put things
  • I can't say what's on the tip of my tongue
  • At the end of the day I haven't got the important stuff done
  • I forget to take my tablets

There are tips and tricks, gadgets and gizmos to help get around cognitive difficulties. You will also find suggestions on how friends and family, as well as health professionals, may be able to help. Publications and videos are available through the Staying Smart web site.

Research by topic areas...

Diagnosis

Marrie RA, Yu N, Wei Y, et al.
High rates of physician services utilization at least five years before multiple sclerosis diagnosis.
Mult Scler. 2012 Dec 21. [Epub ahead of print]
abstract

Symptoms and symptom management

Salter AR, Tyry T, Vollmer T, et al.
"Seeing" in NARCOMS: a look at vision-related quality of life in the NARCOMS registry.
Mult Scler. 2012 Dec 20. [Epub ahead of print]
abstract

Solaro C, Trabucco E, Messmer Uccelli M.
Pain and multiple sclerosis: pathophysiology and treatment.
Curr Neurol Neurosci Rep. 2013 Jan;13(1):320.
abstract

Adamec I, Lovrić M, Zaper D, et al.
Postural orthostatic tachycardia syndrome associated with multiple sclerosis.
Auton Neurosci. 2013 Jan;173(1-2):65-8.
abstract

Zecca C, Manconi M, Fulda S, et al.
Restless legs syndrome in multiple sclerosis.
CNS Neurol Disord Drug Targets. 2012 Dec 12. [Epub ahead of print]
abstract

Disease modifying treatments

Havla J, Tackenberg B, Hellwig K, et al.
Fingolimod reduces recurrence of disease activity after natalizumab withdrawal in multiple sclerosis.
J Neurol. 2012 Dec 25. [Epub ahead of print]
abstract

Drugs in development

Comi G, Cook SD, Giovannoni G, et al.
MRI outcomes with cladribine tablets for multiple sclerosis in the CLARITY study.
J Neurol. 2012 Dec 21. [Epub ahead of print]
abstract

Comi G, Hartung HP, Kurukulasuriya NC, et al.
Cladribine tablets for the treatment of relapsing-remitting multiple sclerosis.
Expert Opin Pharmacother. 2013 Jan;14(1):123-36.
abstract

Epidemiology

Iuliano G, Boz C, Cristiano E, et al.
Historical changes of seasonal differences in the frequency of multiple sclerosis clinical attacks: a multicenter study.
J Neurol. 2012 Dec 21. [Epub ahead of print]
abstract

Grytten N, Torkildsen O, Aarseth JH, et al.
Month of birth as a latitude-dependent risk factor for multiple sclerosis in Norway.
Mult Scler. 2012 Dec 20. [Epub ahead of print]
abstract

Co-existing conditions

Sternberg Z, Leung C, Sternberg D, et al.
The prevalence of the classical and non-classical cardiovascular risk factors in multiple sclerosis patients.
CNS Neurol Disord Drug Targets. 2012 Dec 12. [Epub ahead of print]
abstract

Assessment tools

Baroin A, Chopard G, Siliman G, et al.
Validation of a new quality of life scale related to multiple sclerosis and relapses.
Qual Life Res. 2012 Dec 18. [Epub ahead of print]
abstract

van Vliet R, Hoang P, Lord S, et al.
The Falls Efficacy Scale International: a cross-sectional validation in people with multiple sclerosis.
Arch Phys Med Rehabil. 2012 Dec 12. doi:pii: S0003-9993(12)01212-9.10.1016/j.apmr.2012.10.034. [Epub ahead of print]
abstract

Hawton A, Green C, Telford C, et al.
Using the multiple sclerosis impact scale to estimate health state utility values: mapping from the MSIS-29, version 2, to the EQ-5D and the SF-6D.
Value Health. 2012 Dec;15(8):1084-91.
abstract

Quality of life

Glanz BI, Dégano IR, Rintell DJ, et al.
Work productivity in relapsing multiple sclerosis: associations with disability, depression, fatigue, anxiety, cognition, and health-related quality of life.
Value Health. 2012 Dec;15(8):1029-35.
abstract

Causes of MS

Salzer J, Hallmans G, Nyström M, et al.
Smoking as a risk factor for multiple sclerosis.
Mult Scler. 2012 Dec 20. [Epub ahead of print]
abstract

Vitamin D

Pozuelo-Moyano B, Benito-León J, Mitchell AJ, et al.
A systematic review of randomized, double-blind, placebo-controlled trials examining the clinical efficacy of vitamin d in multiple sclerosis.
Neuroepidemiology. 2012 Dec 18;40(3):147-153. [Epub ahead of print]
abstract

Derakhshandi H, Etemadifar M, Feizi A, et al.
Preventive effect of vitamin D3 supplementation on conversion of optic neuritis to clinically definite multiple sclerosis: a double blind, randomized, placebo-controlled pilot clinical trial.
Acta Neurol Belg. 2012 Dec 19. [Epub ahead of print]
abstract

Paediatric MS

Etemadifar M, Afzali P, Tabrizi N, et al.
Pediatric multiple sclerosis with primary progressive course-report of a retrospective cohort study in Iran.
Neuropediatrics. 2012 Dec 19. [Epub ahead of print]
abstract

Psychological aspects

Foroughipour M, Behdani F, Hebrani P, et al.
Frequency of obsessive-compulsive disorder in patients with multiple sclerosis: A cross-sectional study.
J Res Med Sci. 2012 Mar;17(3):248-53.
abstract

Sarısoy G, Terzi M, Gümüş K, et al.
Psychiatric symptoms in patients with multiple sclerosis.
Gen Hosp Psychiatry. 2012 Dec 20. doi:pii:S0163-8343(12)00329-5. 10.1016/j.genhosppsych.2012.10.011. [Epub ahead of print]
abstract

Economics

Agashivala N, Kim E.
Cost-effectiveness of early initiation of fingolimod versus delayed initiation after 1 year of intramuscular interferon beta-1a in patients with multiple sclerosis.
Clin Ther. 2012 Jul;34(7):1583-90.
abstract

Prognosis

Tadayyon F, Etemadifar M, Bzeih H, et al.
Association of urodynamic findings in new onset multiple sclerosis with subsequent occurrence of urinary symptoms and acute episode of disease in females.
J Res Med Sci. 2012 Apr;17(4):382-5
abstract

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