June 19 (HealthDay News) -- The olfactory bulb in the brain -- the brain's "smell center" -- may change in size as a person's sense of smell changes, a German study reports.

In this study, researchers at the University of Dresden Medical School studied 20 people with loss of sense of smell. At the start of the study, the patients underwent an assessment that included MRI of the brain and nasal endoscopy, an examination of the inside of the nose using a flexible instrument called an endoscope. Their ability to detect odors, discriminate between odors and identify particular odors was also tested. The full assessment was repeated 13 to 19 months later.

At the first assessment, seven of the 20 patients had no sense of smell (anosmia) and 13 had a reduced sense of smell (hyposmia). At the second assessment, six had anosmia and 14 had hyposmia, the study found.

In patients who initially had hyposmia, the volume of the olfactory bulb increased as the patients' sense of smell increased. But there was no correlation between the volume of the olfactory bulb and the ability to distinguish between or identify specific odors.

The study was published in the June issue of the journal Archives of Otolaryngology -- Head & Neck Surgery.

"The correlation between olfactory bulb volume and olfactory function may potentially be used in combination with other factors influencing olfaction such as remaining olfactory function, age and duration of olfactory loss as a means to provide patients with individual information on the prognosis of their disease," the study authors wrote.

"Hypothetically, a multifactorial approach could be applied to eventually come up with a formula that would allow a more precise prognosis of olfactory function. Especially since therapeutic options in patients with olfactory loss are limited, at present, this type of information is of high clinical significance."

SOURCE: JAMA/Archives journals, news release, June 16, 2008