26.1.2016
Daniel Mendelsohna, b,
Wim J. Riedela and
Anke Sambetha,
,
aDepartment of Neuropsychology and
Psychopharmacology, Faculty of Psychology and Neuroscience,
Maastricht University, P.O. Box 616, NL-6200 MD Maastricht, The
Netherlands
bSchulich School of Medicine and Dentistry, The
University of Western Ontario, London, Ontario, Canada
The serotonergic system is implicated in the regulation of mood and cognition. Acute tryptophan depletion (ATD) is an experimental procedure for lowering central serotonin levels. Here, the effects of ATD on psychomotor processing, declarative memory, working memory, executive functions and attention are discussed.
The most robust finding is that ATD impairs the consolidation of episodic memory for verbal information. Semantic memory appears to be unaffected by ATD although a limited variety of tasks examined effects in this domain. Similarly, evidence suggests ATD does not influence verbal, spatial and affective working memory.
Most studies investigating effects on executive functions have produced non-specific or negative findings. In terms of attention, ATD either does not affect or may improve focused attention and ATD likely does not impact sustained and divided attention or attentional set-shifting. Although ATD is known to affect mood in certain vulnerable populations, the effects of ATD on cognition in non-vulnerable participants are independent of mood changes. Suggestions for future directions and implications for psychiatric illnesses are discussed.
Keywords: Tryptophan depletion; Serotonin; Cognition; Memory; Attention; Executive function