Brain stimulation methods are designed to temporarily alter the way the brain behaves; by facilitating or inhibiting normal response patterns. They are commonly used to understand which brain areas play a role in certain functions as observed by changes in task performance. Stimulation methods are also currently being trialled as potential rehabilitation aids and/or treatments for a number of neurological and psychiatric conditions, e.g., stroke or depression. Transcranial direct current stimulation (tDCS) alters the resting potential of neurons and can also produce changes in the concentration of key excitatory and inhibitory neurochemicals. Typically, a weak electric current is passed through two electrode pads placed on the surface of the scalp in a configuration designed to target particular brain regions of interest. Here in Swansea, we seek to modify mood and cognition in both young and older adults using the technique.