**2.3 Efficacy of EEG-biofeedback in the treatment of ADHD**

The first study of EBF in ADHD (J. F. Lubar & Shouse, 1976) reported improved attention and normalized levels of arousal, together with improved grades and achievement scores for the (eight) children under treatment. Subsequent studies have reported similarly positive results, showing improvements of behaviour, attention and impulsivity (Alhambra et al., 1995; Carmody et al., 2000; Drechsler et al., 2007; Gevensleben et al., 2010; Gevensleben et al., 2009; Heinrich et al., 2004; Kaiser & Othmer, 2000; Kropotov et al., 2005; Leins et al., 2007; Linden et al., 1996; J.F. Lubar et al., 1995; J. F. Lubar, 1991; Rossiter, 1998; Rossiter & La Vaque, 1995; Strehl, et al., 2006; Thompson & Thompson, 1998; Doehnert et al., 2008). Efficacy of EBF is comparable to psychostimulant medication and group (CBT) therapy programs with effects lasting 6 months and longer (Fuchs et al., 2003; Gani et al., 2009; Gevensleben et al., 2010; Kaiser, 1997; Leins et al., 2007; Linden et al., 1996; J.F. Lubar et al., 1995; Monastra et al., 2002; Rossiter & La Vaque, 1995; Thompson & Thompson, 1998). Overall, EBF treatment results in clinical improvement in about 75% of the cases, without any reported adverse effects so far (Leins et al., 2007; Monastra et al., 2005).

It should be noted, however, that the use of the theta/beta ratio as marker of general arousal has been questioned, because it does not correlate with skin conductance level (R.J. Barry & Clarke, 2009; R.J. Barry et al., 2009). Similarly, SCPs are no direct correlates of arousal but rather represent attentional processes (Siniatchkin et al., 2000). This raises the interesting notion that in ADHD, EBF may not restore or modulate arousal systems per se, but compensate underarousal by strengthening cognitive functions that have been negatively affected by the arousal dysfunction.
