Cognitive function is related to fronto-striatal serotonin transporter levels--a brain PET study in young healthy subjects.
BACKGROUND
Pharmacological manipulation of serotonergic neurotransmission in healthy volunteers impacts on cognitive test performance. Specifically, markers of serotonin function are associated with attention and executive functioning, long-term memory, and general cognitive ability. The serotonin transporter (SERT) protein is a key regulator in the serotonin system. We hypothesized that higher performance on tests sensitive to serotonin would be associated with higher SERT levels in specific fronto-striatal brain regions.


METHODS
Thirty-two healthy subjects (25 males, mean age 26.0 years, range 19-37) underwent positron emission tomography using the SERT ligand [(11)C]DASB. Subjects underwent the following tests: Stroop Color Word Test, Trail Making Test B, Rey's Auditory Verbal Learning Test and Complex Figure Test, logical reasoning subtest from Intelligenz-Struktur-Test 2000 R, and a Danish version of National Adult Reading Test.


RESULTS
We found positive associations between performance on the Stroop Color Word Test and right-sided dorsolateral prefrontal SERT binding (R(2) = 0.12, p = 0.048). Furthermore, scores of logical reasoning (correlating with IQ) and educational level associated positively with SERT binding in the caudate, most prominent on the left side (logical reasoning: R(2) = 0.34, p = 0.0026 (left), R(2) = 0.2, p = 0.022 (right), educational level: R(2) = 0.19, p = 0.012 (left), R(2) = 0.15, p = 0.027 (right)). Scores of logical reasoning also associated with left-sided ventrolateral prefrontal cortex (R(2) = 0.24, p = 0.014). There were no significant associations between SERT binding and tests of long-term episodic memory.


CONCLUSIONS
The results imply that in healthy subjects, high SERT binding in fronto-striatal regions is associated with better performance on tasks involving executive function and logical reasoning.
Madsen
Karine
K
The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Erritzoe
David
D
Mortensen
Erik Lykke
EL
Gade
Anders
A
Madsen
Jacob
J
Baaré
William
W
Knudsen
Gitte M
GM
Hasselbalch
Steen G
SG
D000328:Adult; D003071:Cognition / Q000502:physiology*; D003342:Corpus Striatum / Q000378:metabolism; D056344:Executive Function / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism; D006801:Humans; D008128:Logic; D008297:Male; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography / Q000379:methods*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D057190:Stroop Test; D055815:Young Adult
D050486:Serotonin Plasma Membrane Transport Proteins