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Olfactory disorder signs of Alzheimer's and Parkinson's

Olfactory disorder signs of Alzheimer's and Parkinson's

Smell disorders can indicate illnesses

Many people suffer from a loss of smell without perceiving it as a serious impairment. However, the olfactory disorders can be an expression of diseases such as “inflammation of the nose or sinuses” or of traumatic brain injuries, reports the Clinic for Otorhinolaryngology at the University Clinic in Cologne. In addition, studies - for example at the TU Dresden - have found a connection between the loss of sense of smell and the occurrence of Parkinson's. In addition, the specialist magazine "Archives of General Psychiatry" published several articles in 2007, in which the possible connections between Alzheimer's and the loss of smell are pointed out.

Smells are usually perceived much less consciously than pictures or sounds, which is why people often hardly notice a smell disorder at first. Those who can see poorly will usually see an optician or ophthalmologist relatively quickly. In the event of hearing loss, those affected usually go to a specialist promptly. But when the sense of smell fades, it often takes years before even thinking about visiting a doctor. "The loss of the sense of smell can go hand in hand with a considerable loss of quality of life," quotes "Die Welt" the director of the ear, nose and throat clinic at the University Hospital Cologne, Professor Karl-Bernd Hüttenbrink. The consequence is that people with olfactory disorders are also more likely to become depressed. Those affected should not delay the visit to the doctor if they lose their sense of smell.

Sense of smell closely connected to the sense of taste The sense of smell plays an important role in everyday life, even if people often perceive smells subconsciously. For example, the sense of smell is of crucial importance when tasting. If the nose is blocked by a runny nose, the sense of taste also suffers. The so-called "retronasal smell", which significantly influences the sense of taste, is actually the main function of the olfactory organ, according to the Cologne ENT clinic on its website. According to the experts, ascending fragrances are directed into the nose through the throat when drinking or chewing food and during the early phase of the swallowing act. This aromatic taste is "mistakenly often understood as a performance of the tongue, but aromatic perceptions are always olfactory performance", the ENT clinic continues.

Tens of thousands of patients with olfactory disorders According to the experts, people have around 400 different olfactory receptors, which react differently to different fragrance spectra. When appropriate fragrances reach the intended receptors, a signal is passed on to the sensory cells, which creates a unique activity pattern of different receptors depending on the perceived fragrance mixture. This enables a differentiated perception of taste or smell. But the smell perception can be disturbed in different ways. According to the ENT clinic in Cologne, "79,000 patients with olfactory disorders are treated in ENT clinics in Germany alone each year." Sinunasal diseases such as inflammation of the nose or sinuses are the most common cause of the olfactory disorder. According to the expert, impairments of the sense of smell following viral infections are also not uncommon. The olfactory disorders are less common as a result of a traumatic brain injury or toxic damage to the olfactory epithelium. In addition, neurodegenerative diseases such as Alzheimer's and Parkinson's have already been linked to olfactory disorders.

Smell test to diagnose a smell disorder According to the experts, patients who contact a doctor early on because of their smell disorder include (hobby) cooks and wine lovers, i.e. people who become aware of the loss of their sense of taste at an early stage. In the case of other sufferers, however, it can be observed that they delay the visit to the doctor for a very long time. "For a long time, the life partner has to check the perfume or taste the meal they have cooked themselves," emphasized Prof. Hüttenbrink. The otolaryngologist first carries out a smell test, which enables a detailed assessment of the smell. For example, “Fragrances are released from felt pens by removing the pen cap” and held in front of the patient's nose, reports the ENT clinic in Cologne. The test shows which scents the patient can identify and differentiate (identification test and discrimination test) and the intensity at which they perceive the smell (threshold test). In addition, if an olfactory disorder is suspected, a nasal endoscopy is usually carried out, in which the olfactory mucosa is precisely inspected, the Cologne ENT clinic continues. In addition, there is the option of an objective measurement of the sense of smell with the help of recording the olfactory evoked potentials in the brains of the test subjects. The diagnosis differentiates in terms of quantitative olfactory perception, a decreased (hyposmia), a canceled (anosmia) and an increased (hyperosmia) sense of smell.

Causes of olfactory disorders need to be checked If the tests come to the conclusion that there is indeed an impairment of the sense of smell, the doctors look into the question of which diseases are considered to trigger the olfactory disorders in order to subsequently initiate appropriate therapeutic measures. In addition to the inflammation of the nose or paranasal sinuses, viral infections and their late effects as well as possible head injuries must also be checked. Allergies can also lead to swelling of the mucous membranes, a blocked nose and corresponding impairment of the sense of smell, so that an allergy test may be appropriate. If the causes of the olfactory disorder cannot be determined in the usual examinations, a possible Parkinson's or Alzheimer's disease should also be considered. The loss of sense of smell has already been identified in several studies as an early sign of these neurodegenerative diseases.

Smell training to rebuild the sense of smell At the Technical University of Dresden, researchers led by Professor Thomas Hummel have been testing the use of smell training against the loss of smell for some time and have achieved considerable success in some cases. The twelve-week training course, in which patients should smell four vials with different scents twice a day (morning and evening), has led to significant improvements in the sense of smell in patients with anosmia, according to the experts. The doctors assume that olfactory training will give rise to new odor receptors and that the test subjects will also learn to perceive smells better. Those affected can literally train their sense of smell with the help of olfactory training. However, if the loss of sense of smell is based on a disease, appropriate treatment should be given first before the olfactory training attempts to rebuild the sense of smell. (fp)

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