Figure 3. Relationship between olfaction, plasma norepinephrine levels in the supine position (top) and heart rate response after 3 minutes of head up tilt (bottom).

Patients with autonomic failure and were later diagnosed MSA (red) had normal olfactory function, tended to have plasma norepinephrine levels that were not low, and greater chronotrophic response to head up tilt. Those that converted to PD or DLB (grey) had impaired olfaction, tended to have lower norepinephrine levels, and a lesser heart rate response to tilt. Patients who remained as pure autonomic failure without signs of CNS involvement are shown in white. Circles represent clusters of patient groups. UPSIT: University of Pennsylvania Smell Identification Test.