Indeed,  during odor delivery in sleep the researchers noted that the two hemispheres of the subjects’ brains exhibited the kind of electrical activity thought to be involved in memory consolidation, with the half that was “smelling the roses” showing the more synchronized activity that is important for the consolidation process. When the subjects woke up and retook the test, they were better at remembering the locations of words that had been presented to the side of the brain that had been stimulated with the smell while they slept.

— Read more in One-Sided Memories and Sleep: A unique sleep experiment to uncover brain activity comes up smelling of roses at Weizman Institute.

In their study, which followed nearly 1,800 participants over 10 years, they found that having a consistent strong sense of smell was associated with less risk of dementia onset. The study also considered the relationship between the efficacy of other senses (like hearing and vision) and dementia but concluded that the association with smell was the strongest.

— MindBodyGreen, reporting on a study done at the University of California at San Francisco. Read more in A Continued Strong Sense Of Smell Is Associated With Lower Dementia Risk, Study Says.

...there were 3 sets of identical twins in which one twin had no [olfactory bulb] and the other twin had a normal OB. In all three cases, the person without an OB could actually smell better than their twin. Overall, in that database, they found that 0.6% of women and 4.25% of left-handed women had the same condition.

Read more in People missing the scent region of their brain can still smell at Massive Science.