Benefits of EEG-Neurofeedback on the Modulation of Impulsivity in a Sample of Cocaine and Heroin Long-Term Abstinent Inmates: A Pilot Study

The aim of this pilot study was to assess whether neurofeedback (NFB) can be useful in the treatment of impulsive behavior in long-term abstinent cocaine and heroin addicts. A single-blind sham-controlled NFB protocol was carried out to assess the effects of NFB on impulsivity in 20 (10 + 10) cocaine and heroin long-term abstinent addicts (Diagnostic and Statistical Manual of Mental Disorders [4th ed., text rev.; DSM-IV-TR]). Psychotic and neurologic diseases were excluded. Participants underwent 40 NFB sessions based on the very slow cortical potential range. Inhibitory deficits were specifically addressed through right and left prefrontal training. Clinical improvement was measured with Likert-type scales, the Hamilton Depression Rating Scale, and the State-Trait Anxiety Inventory, and impulsivity was assessed using the Barratt Impulsiveness Scale and the Continuous Performance Test. Although the results are preliminary due to the small sample size, the NFB-treated group showed a significant clinical improvement, including symptoms of anxiety and depression, with two differentiated time periods. No significant clinical improvement was found in the control group. A significant decrease in the post- versus pre-treatment measures of global impulsivity, nonplanning impulsivity, and error commission measures was found in the NFB-treated group; effect size (d_Korr) in the pre-post control design was moderate. No significant change was found in the control group. Despite the limitations of this study, the results suggest that NFB is better than placebo in improving impulsivity and clinical symptoms of anxiety and depression in long-term abstinent cocaine- and heroin-dependent individuals.

IL-6 and TNF-α in unmedicated adults with ADHD: Relationship to cortisol awakening response

There is preliminary evidence that the immune system's cytokines may have impact on ADHD in children. Nevertheless, studies exploring the possible role of pro-inflammatory cytokines in adults with ADHD are lacking. This study aimed to assess differences in serum IL-6 and TNF-α between patients and controls and their possible relationship to resting cortisol. 108 adults with ADHD (DSM-IV), 44 inattentive and 64 combined, age ranging between 18 and 55 years, and 27 healthy controls were included. Major psychiatric disorders and organic comorbidities were excluded. Serum samples for IL-6 and TNF-α and salivary samples to assess cortisol awakening response were collected on the same day. Analysis of variance was applied to study differences in IL-6 and TNF-α between groups. Pearson correlations were used to study associations between IL-6, TNF-α, and CAR. There were no significant differences in serum IL-6 or TNF-α levels between patients and controls or between combined and inattentive patients. Negative associations between IL-6 (r=-0.386, p=0.020), TNF-α (r=-0.372, p=0.023) and cortisol awakening response were found in the inattentive subtype, whereas no association was seen in the combined subtype. A negative correlation between IL-6 and cortisol was also present in the control group (r=-0.44, 0.030). The peripheral pro-inflammatory markers, IL-6 and TNF-α, do not appear to be primarily involved in ADHD in adults, although the role of other inflammatory markers cannot be ruled out. The differences regarding the association between IL-6 and TNF-α and morning cortisol response suggest possible underlying neurobiological differences between the inattentive or combined patients that merit further studies.

Cortisol awakening response in adults with attention deficit hyperactivity disorder: Subtype differences and association with the emotional lability

Cortisol awakening response (CAR) has been studied in children with ADHD, and some authors have reported morning cortisol differences among ADHD subtypes. Despite, only half of the children with ADHD continue to exhibit the disorder into adulthood, CAR has not been studied in adults so far. One hundred and nine adults with ADHD according to the DSM-IV criteria (46 inattentive and 63 combined) ranging in age from 18 to 55 years, and 27 healthy controls were included. Psychiatric and organic comorbidities were excluded. Salivary cortisol samples were obtained at 0, 30, 45 and 60 minutes after awakening. CAR was present in 84% of the healthy controls but in only 64% of the adults with ADHD (68% of the inattentive and 61% of the combined were CAR-positive). There were no significant differences in any of the morning cortisol measures between patients and controls or between the combined and inattentive subtypes of ADHD. Among the inattentive subtype but not in the combined patients, significant positive correlations were observed between the CAR and emotional lability (p=0.05), or self-concept (p=0.014) CAARS subscales, as well as with the cognitive impulsivity subscale of the Barratt impulsiveness scale (p=0.028). These results suggest that adults with ADHD exhibit normal cortisol responses upon awakening and thus cannot be defined in terms of hypo-arousal. Neurobiological differences between the combined and inattentive subtypes involving cortisol, are discussed.

[The dopaminergic system and addictions]

AIM

All psychoactive substances with a high abuse potential are characterized by altering the mesocorticolimbic dopaminergic neurotransmission system. In this article it is proposed to review the neurobiological mechanisms that comprise the foundation of the development of addiction.

DEVELOPMENT

The acute drug intake provokes an increase in extracellular dopamine which, in vulnerable individuals, could be the start of the addictive process. Chronic drug use is accompanied by a reduction in the dopaminergic function with the development of neuroadaptive changes in the mesolimbic and mesocortical pathways. In the prefrontal cortex, the changes in dopaminergic function produce an inbalance between receptors D1 and D2, which leads to a predominance of inhibitatory function. Dopaminergic innervation in the amygdala and its interaction with the nucleus accumbens plays an essential role in the conditioning of environmental stimuli, and can trigger the craving and relapse. In drug dependent patients, dopaminergic changes extend from the limbic regions to the associative and sensorimotor striatum, and affect the cortico-striatico-cortical circuits.

CONCLUSION

The involvement of the dopaminergic systems is crucial in the development of addiction, from the early phases in which drug use begins as an object-directed instrumental behavior, to the consolidation of the addiction as a compulsive habit, controlled by stimulus-response mechanisms, which progressively invade all aspects of the life of an individual.