Xe-133 SPECT cerebral blood flow study in a healthy population: Determination of T-scores

Dementia is becoming a major health problem as the population of the Northe rn Hemisphere ages. Early differential diagnosis between normal cognitive d ecline and dementia is particularly difficult. If psychometric evaluation c an contribute to the diagnosis, quantitative cerebral functional imaging wo uld play an important role. We therefore proposed, first, to constitute a n ormative dataset that could later be used to identify subjects at risk for neurodegenerative processes and, second, to describe the risk of abnormal g lobal cerebral blood flow (gCBF) by defining categories based on the standa rdized cutoff scores of a young, healthy population (T-score). Methods: Of a total of 203 healthy volunteers, 187 were included in the protocol, which included evaluation of medical history, neurologic and neuropsychologic st atus, and body composition; analysis of blood; and measurement of gCBF by m eans of Xe-133 SPECT. Results: With ANOVA analysis using age and sex as bet ween-subject factors and gCBF as a within-subject factor, a significantly h igher gCBF was found in women than in men. In addition, a linear reduction as a function of age was observed for both sexes (-0.3%/y). T-score was det ermined for the 18- to 28-y-old age group, for whom gCBF was found to be 46 .7 +/- 5.1 mL/min/100 g tissue in men and 49.0 +/- 5.0 mL/min/100 g tissue in women. The age-dependent decrease could thus be expressed in T-scores an d, in the 29- to 38-y-old, 39- to 48-y-old, and >48-y-old age groups, avera ged -0.63, -1.29, and -1.92, respectively, in men and -0.63, -0.83, and -2. 40, respectively, in women. Cognitive performance, body composition, and bl ood analysis revealed the expected significant effects from sex and age. Co nclusion: The large-scale reference database of gCBF measurements constitut ed from a healthy, well-controlled population enabled age and sex stratific ation, which showed significant differences between the sexes and a signifi cant decline as a function of age. T-scores were determined and warrant fur ther studies on the prospective identification of early dementia by Xe-133 SPECT in elderly individuals.