The aim of this study is to assess whether the application of a selective serotonin reuptake inhibitor (SSRI) enhances and prolongs the learning enhancement achieved by anodal transcranial direct current stimulation (atDCS). For this, young and older healthy subjects will be tested with a well established learning paradigm. Results of this study may help to support the application of atDCS also in patients, e.g. with dementia or mild cognitive impairment.

Inclusion Criteria:

• right handedness
• unobtrusive neuropsychological screening
• ability to provide written informed consent
• no pathological findings in head MRI
• age: 18 to 35 years (young adults) or 50-80 years (older adults)
• Highly effective contraception (Pearl Index < 1) or reliable abstinence from any heterosexual relationships in women of childbearing potential

Exclusion Criteria:

• severe internal or psychiatric disease (especially depression or suicidal thoughts)
• epilepsy
• cognitive impairment (< SD under age adjusted norm in neuropsychological testing)
• concurrent taking of serotonin precursors (tryptophan, 5-HTP) or MAO inhibitors
• concurrent taking of tramadol or triptans
• concurrent taking of pimozide or linezolid
• concurrent taking of other drugs prolonging the QT-interval
• long-QT-syndrome
• hypokalemia or hypomagnesemia
• known intolerance of the study medication
• claustrophobia or metallic implants, tattoos (MRI exclusion criteria)
• pregnancy or lactation
• participation in another drug-interventional clinical trial within the last month or during the entire study
• probands that are placed in an institution due to official or judicial order
• non-agreement to save and transmit pseudonymised study data within the clinical trial