The effects of acute tryptophan depletion on neuropsychological function, mood and movement in the healthy elderly

Few studies have investigated the function of the serotonin (5-HT) system in the elderly. Previous studies have shown effects of reducing serotonin function, by acute tryptophan depletion (AID), on neuropsychologicat function in healthy subjects but this technique has not previously been employed over a wide age range in the elderly. This study compared the effects of AID on mood, cognitive function and motor function in two groups of healthy volunteers, one group aged 50-69 and the other aged 70-89. The effects of AID were investigated in a double-blind, placebo-controlled, counterbalanced, crossover, randomized design. The effects of ATD were not significantly different between age groups, suggesting that there is relatively little functional change across these age ranges. Compared with studies in much younger age groups there was, however, more evidence of an adverse effect of AID on psychomotor function and working memory. There was no effect of AID on mood despite inclusion of subjects with a family history of depression.