Striatal hypometabolism distinguishes striatonigral degeneration from Parkinson's disease.

Regional and global metabolic rates for glucose were estimated using 18F-fluorodeoxyglucose and positron emission tomography in 10 patients with a clinical likelihood of striatonigral degeneration (2 men and 8 women; mean age, 61.8 +/- 6.9 years; mean disease duration, 4.7 +/- 2.2 years; mean Hoehn and Yahr score, 3.5 +/- 0.8). Measures of brain glucose metabolism in these patients were compared with those for 10 age-matched normal volunteers, 10 disease severity-matched patients with Parkinson's disease (PD), and 10 disease duration-matched patients with PD. Normalized glucose metabolism was significantly reduced in the caudate (p < 0.03) and putamen (p < 0.003) as compared with that in normal and PD control subjects, and discriminated patients with striatonigral degeneration from control subjects (p < 0.002). Putamenal hypometabolism in patients with striatonigral degeneration correlated significantly with quantitative ratings of motor disability (p < 0.02). These results suggest that quantitative 18F-fluorodeoxyglucose positron emission tomography techniques may be useful in supporting a diagnosis of striatonigral degeneration in life, and in objectively assessing disease severity and potential therapeutic interventions.

Taste differences between cigarette smokers and nonsmokers.

In a series of taste tests, cigarette smokers allowed to smoke, cigarette smokers not allowed to smoke, and nonsmokers, rated the pleasantness and intensity of sugar, salt, and quinine solutions. One taste test was performed before, and three tests were completed after, ingestion of a glucose load. Before the glucose load, there were no significant differences between the groups in rating test solutions. After the glucose load, the smokers allowed to smoke significantly decreased their ratings of the pleasantness of very sweet solutions. In contrast, nonsmokers and smokers-not-smoking did not significantly decrease their ratings of the pleasantness of sweet tastes. None of the subjects significantly changed their intensity ratings after the glucose load, nor did they change their pleasantness and intensity ratings of salt and quinine solutions.

Failure of preference formation in amnesia.

Information about the frequency of a stimulus influences the formation of preference judgments in normal subjects. In contrast, results show that patients who have amnesic syndromes have difficulty generating preferences on the basis of frequency information. It is unlikely that difficulty in forming preferences is caused merely by poor mnemonic capacity. Patients with amnesia may lack the affective response to stimuli that may be important for remembering events.