Plasma somatostatin and gastrointestinal peptides in Alzheimer's disease and vascular dementia

Few markers distinguish between different dementia types. As dementia affec ts many body systems outside the central nervous system, we investigated ga strointestinal regulatory peptides as possible disease markers in Alzheimer 's Disease (AD) and vascular dementia (VaD). Subjects with mild-to-moderate dementia were diagnosed as probable AD and VaD according to defined criter ia. Gastrointestinal peptides were stimulated using a standardized meal tes t, administered after an overnight fast to 58 dementia patients (40 AD, 18 VaD) and 47 controls matched for age and sex. Blood samples were taken at d esignated time intervals, and basal and stimulated plasma concentrations of eleven peptides were determined by radio-immunoassay. Results were analyse d using the Kruskal-Wallis one-way analysis of variance; the Mann-Whitney U test was used in post hoc analysis where appropriate. There were significa nt differences in somatostatin levels but in none of the other peptides. Ba sal somatostatin was significantly increased in VaD compared to controls (p <0.05), and AD (p <0.005). Maximum stimulated levels were significantly el evated in VaD compared to AD (p <0.01). Median basal and stimulated levels of somatostatin were increased in VaD compared to AD, but the overlap in in dividual values between the groups makes it unlikely to be useful in distin guishing the two types of dementia.