Transcranial direct current stimulation of the prefrontal cortex modulates the desire for specific foods
Introduction
Increasing evidence suggests that the control of eating origins in neural networks associated with decision-making (Pignatti et al., 2006). Although several factors influence the decision of food consumption, such as levels of blood sugar, hormonal changes, food availability, emotional state (including anxiety and depression), physical activity, memory, this information is finally processed in the neural networks associated with decision-making such as the prefrontal cortex, resulting in a final action. Therefore one possible approach to regulate food craving might be to interfere with this decision-making process by changing the activity of the dorsolateral prefrontal cortex (DLPFC).
Several studies from our and other groups have already shown that the prefrontal cortex modulates drug craving and decision-making. For instance, noninvasive brain stimulation, namely repetitive transcranial magnetic stimulation (rTMS), of the DLPFC significantly reduces smoking (Eichhammer et al., 2003, Fregni et al., in press), cocaine (Camprodon, Martinez-Raga, Alonso-Alonso, Shih, & Pascual-Leone, 2007) and alcohol (Boggio et al., 2008) craving. Indeed, one of the most important areas participating in the cue-associated anticipation and planning of drug use involves DLPFC, an area involved in planning and memory (Wilson, Sayette, & Fiez, 2004). For food craving, it was shown that high-frequency (10 Hz) rTMS of the left dorsolateral prefrontal cortex decreases food craving in women with frequent cravings for food. Specifically, the results of this study demonstrated that food craving during exposure to foods remained constant in the active treatment group but increased in the sham treatment group (Uher et al., 2005) after exposure to real food. Finally, we showed that stimulation of the dorsolateral prefrontal cortex is associated with decreased risk-taking in the BART task (Fecteau et al., 2007a). Indeed it has been shown that craving (particularly for cocaine) is associated with specific sensations similar to those of individuals engaged in risky behavior (Goeders, 2002).
In the present study, we tested whether modulation of prefrontal cortex with another technique of noninvasive brain stimulation, transcranial direct current stimulation (tDCS), modulates food craving-related behavior. We chose this technique because it modulates brain activity significantly in a safe, powerful and painless way and its effects can last for more than an hour (Nitsche et al., 2003, Nitsche and Paulus, 2000, Nitsche and Paulus, 2001). It is a technically simple tool in which a continuous weak electric current is applied to the brain via large electrodes that are placed on the scalp of the subject. The effects of tDCS depend on the direction of the electric current, anodal stimulation increases brain activity and excitability and cathodal stimulation reduces it (Nitsche et al., 2003, Antal et al., 2001). Several well-conducted studies in animals and humans confirmed the behavioral and neurophysiological effects of tDCS (Bindman, Lippold, & Redfearn, 1964; Nitsche et al., 2003, Purpura and McMurtry, 1965). In fact, in humans, it has been shown that: anodal stimulation increases cortical excitability in the motor and visual cortex and cathodal stimulation decreases it (Nitsche & Paulus, 2000, 2001). Furthermore the effects of 13 min of tDCS on cortical excitability can last up to 90 min after the end of the stimulation (Nitsche & Paulus, 2001), most probably due to changes of NMDA receptor-efficacy (Nitsche et al., 2003). TDCS, as used in current protocols, is safe in humans as shown by neuropsychological testing (Fregni, Boggio, Lima et al., 2006; Iyer et al., 2005), EEG assessment (Iyer et al., 2005), a neuroimaging study (Nitsche et al., 2004) and brain metabolites evaluation (Nitsche & Paulus, 2001). Finally, recent modeling studies have shown that the amount of electric current going to the brain is large enough to induce a modulation of brain activity (Miranda, Lomarev, & Hallett, 2006; Wagner et al., 2007).
In this study, we tested the hypothesis that bilateral stimulation of prefrontal cortex with tDCS is suited to reduce food craving. Therefore a placebo-tDCS-controlled, randomized, double-blind, crossover study was performed.
Section snippets
Study subjects
Subjects were recruited by local advertising in websites, flyers and notices distributed throughout local universities. We used the same inclusion criteria as the study of Uher et al. (2005): subjects had frequent (≥3 times/day) and strong urges to eat one of the foods we chose for our experiment (see the list). We included healthy subjects aged between 18 and 55 years. Subjects were excluded if they had any neuropsychiatric disorder, current or past history of alcohol or other drugs abuse, were
Results
Subjects tolerated tDCS well. The adverse effects were mild and similar in the three conditions of stimulation (Table 1 lists the adverse effects). The most frequent adverse effects were scalp burning, headache, local itching, burning sensation and somnolence. They were not significantly different across the three conditions of stimulation (p = 0.98).
Discussion
The results of our study demonstrate that active anode right/cathode left DLPFC stimulation reduced food craving significantly. After sham stimulation, craving was significantly increased by presentation of food-related cues, whereas after anode left/cathode right tDCS, craving levels did not change. These results suggest that both active tDCS conditions had an effect in reducing food craving. Moreover, subjects consumed a smaller amount of food after both active stimulation conditions and,
Conclusion
In conclusion, our study demonstrates that anodal tDCS of the DLPFC can suppress food craving. This finding extends the results of a previous study using rTMS to inhibit craving as it suggests that excitability enhancing strategies of brain stimulation of the right hemisphere might be more effective to reduce food craving and therefore opens an avenue for the exploration of noninvasive brain stimulation for eating disorders.
Acknowledgements
This work was supported by a grant from the Harvard Medical School Scholars in Clinical Science Program (NIH K30 HL04095) to F.F. The authors are thankful to MackPesquisa (Sao Paulo, Brazil) that supported part of this study. The authors are thankful to Barbara Bonnetti for the administrative support.
References (33)
- et al.
Prefrontal cortex modulation using transcranial DC stimulation reduces alcohol craving: A double-blind, sham-controlled study
Drug Alcohol Dependence
(2008) - et al.
One session of high frequency repetitive transcranial magnetic stimulation (rTMS) to the right prefrontal cortex transiently reduces cocaine craving
Drug Alcohol Dependence
(2007) - et al.
A sham-controlled, phase II trial of transcranial direct current stimulation for the treatment of central pain in traumatic spinal cord injury
Pain
(2006) - et al.
Transcranial DC stimulation (tDCS): A tool for double-blind sham-controlled clinical studies in brain stimulation
Clinical Neurophysiology
(2006) - et al.
Modeling the current distribution during transcranial direct current stimulation
Clinical Neurophysiology
(2006) - et al.
Modulation of cortical excitability by weak direct current stimulation—technical, safety and functional aspects
Supplement Clinical Neurophysiology
(2003) - et al.
MRI study of human brain exposed to weak direct current stimulation of the frontal cortex
Clinical Neurophysiology
(2004) - et al.
Effect of left prefrontal repetitive transcranial magnetic stimulation on food craving
Biological Psychiatry
(2005) - et al.
Transcranial direct current stimulation: A computer-based human model study
Neuroimage
(2007) - et al.
The right brain hypothesis for obesity
Journal of American Medical Association
(2007)
External modulation of visual perception in humans
Neuroreport
The action of brief polarizing currents on the cerebral cortex of the rat (1) during current flow and (2) in the production of long-lasting after-effects
Journal of Physiology
High-frequency repetitive transcranial magnetic stimulation decreases cigarette smoking
Journal of Clinical Psychiatry
Activation of prefrontal cortex by transcranial direct current stimulation reduces appetite for risk during ambiguous decision making
Journal of Neuroscience
Diminishing risk-taking behavior by modulating activity in the prefrontal cortex:a direct current stimulation study
Journal of Neuroscience
Treatment of major depression with transcranial direct current stimulation
Bipolar Disorder
Cited by (231)
Neuromodulation for the treatment of Prader-Willi syndrome – A systematic review
2024, NeurotherapeuticsThe Neurobiology of Eating Behavior in Obesity: Mechanisms and Therapeutic Targets: A Report from the 23rd Annual Harvard Nutrition Obesity Symposium
2023, American Journal of Clinical Nutrition