Patients complaining of HT-related olfactory dysfunction typically have anosmia and rarely regain normal olfactory ability, parosmia prevalence decreases over time in such patients, and damage to olfaction-related brain structures can be observed in most such patients using an appropriate MRI protocol.

On standardized tests of odor identification and odor detection, women tend to score better than men at nearly all age groups. We sought to determine if these findings would translate to differences between the sexes in the volume of activated brain when odors are Ž . presented to subjects as the stimulants for functional magnetic resonance imaging FMRI experiments. The activation maps of eight Ž . Ž right-handed women mean age 25.3 years old, range 20-44, S.D. 8.3 years were compared with those of 8 right-handed men mean age . 30.5, range 18-37, S.D. 6.5 years given the same olfactory nerve stimuli in an FMRI experiment at 1.5 T. Olfactory stimuli were delivered to the patients in a passive fashion using a Burghart OM4-B olfactometer with a nose piece inserted into the patients' nostrils. Ž . We used agents eugenol, phenyl ethyl alcohol, or phenyl ethyl alcohol alternating with hydrogen sulfide that were selective for olfactory nerve stimulation in the nose. The odorants were delivered to both nostrils for 1 s every 4 s during a 30 s 'on-period'. During the 30 s 'off-period', the patient received room air at the same flow rate. The women's group-averaged activation maps showed up to eight times Ž . more activated voxels than men for specific regions of the brain frontal and perisylvian regions . The left and right inferior frontal regions showed a statistically significant increase in activation in women at p -0.01. In general, more women showed activation than Ž . men. The results suggest that 1 FMRI activation maps in subject groups can demonstrate correlates to psychophysical tests of olfaction, Ž . and 2 one must control for gender when performing odor-stimulated FMRI experiments. q

The sense of smell shows a diminution with age as measured by the University of Pennsylvania Smell Identification Test (UPSIT). To ascertain whether the volumes of the olfactory bulbs and tracts (OBTs) and the temporal lobes (TL) declined in parallel to smell function, we examined 36 individuals from ages 22 to 78 who did not complain of any loss of the sense of smell using magnetic resonance (MR) imaging. The OBT volumes showed an initial increase to the 4th decade of life and then a decrease with increasing age, while the trend in TL volume was not as dramatic. There was no correlation between OBT or TL volumes with unilateral or total UPSIT scores. The normative data by decades can be used to assess the OBTs of cohorts of patients with neurodegenerative disorders that affect olfaction.

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