Participants

Twenty young (18–35 years) and 20 older (50–80 years) healthy subjects participated in the study. Participants were all right-handed as assessed using the Edinburgh Handedness Inventory (Oldfield, 1971) and had no history of chronic or acute neurologic, psychiatric, or medical disease. Inclusion and exclusion criteria were first checked during a telephone screening (for a complete list, see Supplementary Material). At the screening visit (V0), eligible subjects underwent a medical interview, a neurological examination, comprehensive neuropsychological testing (Supplementary Material and Table 1), electrocardiography, magnetic resonance imaging (MRI) of the brain, and blood sampling (recruitment period: April 2014 to September 2014).

Abbreviations: TAP, test battery for attentional performance; VLMT, verbal learning and memory test.

A p-value ⩽0.05 indicates a significant difference between the groups calculated with a t-test for independent samples unless otherwise noted.

The study was registered at https://clinicaltrials.gov ({"type":"clinical-trial","attrs":{"text":"NCT02092974","term_id":"NCT02092974"}}NCT02092974; name of trial registry: LESO) and conducted in accordance with the Good Clinical Practice guidelines of the Food and Drug Administration and the International Conference on Harmonization. The protocol and all study-specific materials were approved by the German Federal Institute for Drugs and Medical Devices (BfArM) and the Regional Office for Health and Social Affairs in Berlin (LaGeSo; EudraCT: 2013-004821-10). All subjects provided written informed consent before study-specific procedures were conducted and received a small reimbursement for participation.