Practical implications

The positive evaluation of the new NFB protocol for DE behaviors has several practical implications. The following discussion will consider possible fields of application that may be

7. General discussion

135 enriched by the use of NFB in a range of nearby, but also more distant, application fields. Of course, applications in these fields would require initial research.

The most proximate field of application is certainly the treatment of eating disorders that include binge eating behaviors − such as BED and BN − because the aforementioned calls for an evaluation and application of brain-directed treatments specifically arose from intervention research in clinical eating disorders (Iacovino et al., 2012; Schmidt & Campbell, 2013). Here, it has been pointed out that treatments still need improvement regarding outcomes and remission rates (Brownley et al., 2007; Wilson et al., 2007).

The developed NFB protocol was based on an integrative model that takes into account various etiological theories for the development of DE and clinical eating disorders (e.g., Heatherton & Baumeister, 1991; Selby et al., 2008; Stice, 2002; Waters et al., 2001). Regarding the target physiological activity for the NFB, previous results that were distinctly associated with DE predominantly stemmed from objective binge eaters (Tammela et al., 2010). Thus, one could expect the NFB to be effective in populations with clinical eating disorders. Here, NFB may serve as a promising treatment-adjunct, complementing cognitive behavioral therapy as a first-line treatment in BED (Vocks et al., 2010).

One interesting application can be seen in NFB as a treatment-module that could be specifically offered to slow-responders in other psychological treatments, as part of a stepped- care approach (Wilson, Vitousek, & Loeb, 2000). In intervention research on BN and BED, it is a consistent result that certain patients respond rapidly to psychological treatments, showing an early abstinence and improved long-term outcomes (e.g., Bulik, Sullivan, Carter, McIntosh, & Joyce, 1999; Fairburn, Agras, Walsh, Wilson, & Stice, 2004; Hilbert, Hildebrandt, Agras, Wilfley, & Wilson, 2015; Masheb & Grilo, 2007). Patients that do not show an early abstinence from binge eating might be offered NFB as an adjunct in a more intensive treatment. As some previous studies showed that the severe BED and BN symptomatology may be accompanied by specific neuronal deviations (e.g., Friederich, Wu, Simon, & Herzog, 2013; Schienle, Schäfer, Hermann, & Vaitl, 2009), NFB may be especially successful in subgroups with stronger eating pathology that would be less likely to rapidly respond to other treatments.

Another nearby field of application can of course be seen in the general treatment of overweight and obesity. Dieting with calorie restrictions and other behavioral weight-loss practices are still the most common means to target weight loss (Andreyeva et al, 2010; Montani et al., 2015), although long-term success of these practices is limited (Goodrick et al., 1998;

7. General discussion

136 Mann et al., 2007). During the last decades, the importance of psychological and, especially, self-regulatory processes in dysfunctional eating behaviors has gathered more recognition (Berridge, 2009; Wing, Tate, Gorin, Raynor, & Fava, 2006). Here, emotional distress has been highlighted to play a crucial role in the onset of DE behaviors (Selby et al., 2008; Stice, 1994; Waters et al., 2001) and also in the development of overweight and obesity (Hemmingsson, 2014). As Hemmingsson concluded, “these inner disturbances eventually cause a psycho- emotional overload, triggering a cascade of weight gain-inducing effects . . . . Tackling this proposed cause of weight gain could potentially improve both treatment and prevention outcomes.” (2014, p. 769). The distinct scope of the developed NFB protocol to target physiological correlates of tense arousal accompanying affective and motivational antecedents of DE may therefore inform the treatment − and maybe even the prevention − of overweight, and obesity. NFB could be used to support behavioral weight-loss attempts by a reduction of physiological arousal as a risk factor for DE and subsequent dietary failure. Furthermore, an enhancement of self-efficacy, as a commonly known protective factor with regard to dysfunctional eating behaviors (Glasofer et al., 2013; Linde, Rothman, Baldwin, & Jefferey, 2006) could improve results of behavioral weight-loss treatments. In consequence, the probability of associated negative health consequences might be reduced (Guh et al., 2009).

The clinical phenomenon of food addiction constitutes another possible application area for NFB treatments. Food addiction symptoms have frequently been associated with severe binge eating (Avena et al., 2011; Davis, 2013; Gearhardt, Grilo, DiLeone, Brownell, & Potenza, 2011) and weight-regulatory problems (Burmeister, Hinma, Koball, Hoffmann, & Carels, 2013). Several findings from research on shared neuronal circuits and processes between food addiction and other addictions suggest that dysfunctional, brain-regulatory processes in subcortical areas are involved in DE among individuals with food addiction symptoms, for example striatal, insular and prefrontal areas (Gearhardt, Yokum et al., 2011; Jastreboff et al, 2013; Volkow, Wang, & Baler, 2011). Ninaus et al. (2013) showed that attempts to regulate brain activity, even in sham-NFB, can beneficially influence the reestablishment of control- processes in subcortical areas. Thus, NFB may be beneficial to treat food addiction symptoms, given their neuronal underpinnings.

Another argument for possible application of NFB in food addiction has to be seen in the development process of the new NFB protocol: Because of the lack of spectral EEG studies to explain the phenomenology of DE behaviors (Bartholdy et al., 2013; Hume et al., 2015; Tammela et al., 2010), the selection of the targeted EEG high beta activity relied on several

7. General discussion

137 studies from the field of addiction (Parvaz et al., 2011) and EEG correlates of antecedents that are commonly shared in food addiction and substance dependence, like craving and perceived stress (Sinha & Jastreboff; 2013; Styn et al., 2013). Thus, when physiological underpinnings of food and drug addiction are even more similar, the NFB protocol might possibly attain even more effective results.

Regarding these remarks on food addiction, it is of course a small step to consider other addictions, as a possible field of application. In contrast to intervention research in eating dysregulations, researchers in the field of substance-dependence by now have a longer tradition of using NFB (e.g., Dehghani-Arani, Rostami, & Nadali, 2013; Scott, Kaiser, Othmer, S., & Sideroff, 2005). Here, some protocols, such as the Peniston-protocol based on alpha/theta training (Peniston & Kulkolsky, 1990), and its Scott-Kaiser-modification with a training of the sensorimotor rhythm (Scott & Kaiser, 1998), are frequently and successfully applied to alter dysfunctional changes in the spontaneous EEG (for a review, see: Sokhadze et al., 2008).

However, in their review, Sokhadze et al. (2008) pointed out that these traditional protocols might not be suitable for all types of addictions, as EEG baseline changes are not constantly observed for patients with substance-dependence. Besides the positive results in the treatment of DE, the developed NFB protocol took into account several prerequisites that have been stated as important in the treatment of substance dependence: a decrease of the reward value of substance stimuli, alterations of learned, stereotypical seeking-behaviors (craving), and methods to improve inhibitory control-processes (Volkow, Fowler, & Wang, 2004).

Given its foundation in EEG high beta reduction after cue exposure, the developed protocol might posit another optional tool that could be considered in NFB for substance dependence, especially in the absence of EEG baseline alterations and for individuals who do not profit from the Peniston- or Scott-Kaiser-protocols.