A method is described for treating attention deficit hyperactivity disorder, by administering to the individual an anti-epileptic mood stabiliser at a dose which is sub-therapeutic for mood stabilisation, optionally in combination with a psychostimulant. In various embodiments, a predetermined arrangement of a plurality of holes is formed in the semiconductor wafer through a surface of the wafer. A slider drivingly cooperates with the spline, the slider being slidably secured to the driven shaft.