Role of antioxidants in the neurobiology of drug addiction: An update

Relationships between protective enzymatic and non-enzymatic pro-antioxidant mechanisms and addictive substances use disorders (SUDs) are analyzed here, based on the results of previous research, as well as on the basis of our current own studies. This review introduces new aspects of comparative analysis of associations of pro-antixidant and neurobiological effects in patients taking psychoactive substances and complements very limited knowledge about relationships with SUDs from different regions, mainly Europe. In view of the few studies on relations between antioxidants and neurobiological processes acting in patients taking psychoactive substances, this review is important from the point of view of showing the state of knowledge, directions of diagnosis and treatment, and further research needed explanation. We found significant correlations between chemical elements, pro-antioxidative mechanisms, and lipoperoxidation in the development of disorders associated with use of addictive substances, therefore elements that show most relations (Pr, Na, Mn, Y, Sc, La, Cr, Al, Ca, Sb, Cd, Pb, As, Hg, Ni) may be significant factors shaping SUDs. The action of pro-antioxidant defense and lipid peroxidation depends on the pro-antioxidative activity of ions. We explain the strongest correlations between Mg and Sb, and lipoperoxidation in addicts, which proves their stimulating effect on lipoperoxidation and on the induction of oxidative stress. We discussed which mechanisms and neurobiological processes change susceptibility to SUDs. The innovation of this review is to show that addicted people have lower activity of dismutases and peroxidases than healthy ones, which indicates disorders of antioxidant system and depletion of enzymes after long-term tolerance of stressors. We explain higher level of catalases, reductases, ceruloplasmin, bilirubin, retinol, α-tocopherol and uric acid of addicts. In view of poorly understood factors affecting addiction, analysis of interactions allows for more effective understanding of pathogenetic mechanisms leading to formation of addiction and development the initiation of directed, more effective treatment (pharmacological, hormonal) and may be helpful in the diagnosis of psychoactive changes.

Initial Study on COMT and DRD2 Gene Polymorphisms as Well as the Influence of Temperament and Character Trait on the Severity of Alcohol Craving in Alcohol-Dependent Patients

The main aim of this work was to determine the impact of COMT and DRD2 gene polymorphisms together with temperament and character traits on alcohol craving severity alcohol-dependent persons. The sample comprised of 89 men and 16 women (aged 38±7). For the sake of psychological assessment various analytic methods have been applied like the Short Alcohol Dependence Data Questionnaire (SADD), Penn Alcohol Craving Scale (PACS) or Temperament and Character Inventory (TCI) test. The SNP polymorphism of the analyzed genes was determined by Real Time PCR test. The results showed, that the COMT polymorphismmay have an indirected relationship with the intensity and changes in alcohol craving during abstinence. The DRD2 receptor gene polymorphisms are related with the intensity of alcohol craving. It seems that the character traits like “self-targeting”, including “self-acceptance”, are more closely related to the severity of alcohol craving and polymorphic changes in the DRD2 receptor than temperamental traits. Although this is a pilot study the obtained results appeared to be promising and clearly indicate the link betweengene polymorphisms alcohol craving and its severity.

Comparison of Smoothing Filters' Influence on Quality of Data Recorded with the Emotiv EPOC Flex Brain-Computer Interface Headset during Audio Stimulation

Off-the-shelf, consumer-grade EEG equipment is nowadays becoming the first-choice equipment for many scientists when it comes to recording brain waves for research purposes. On one hand, this is perfectly understandable due to its availability and relatively low cost (especially in comparison to some clinical-level EEG devices), but, on the other hand, quality of the recorded signals is gradually increasing and reaching levels that were offered just a few years ago by much more expensive devices used in medicine for diagnostic purposes. In many cases, a well-designed filter and/or a well-thought signal acquisition method improve the signal quality to the level that it becomes good enough to become subject of further analysis allowing to formulate some valid scientific theories and draw far-fetched conclusions related to human brain operation. In this paper, we propose a smoothing filter based upon the Savitzky-Golay filter for the purpose of EEG signal filtering. Additionally, we provide a summary and comparison of the applied filter to some other approaches to EEG data filtering. All the analyzed signals were acquired from subjects performing visually involving high-concentration tasks with audio stimuli using Emotiv EPOC Flex equipment.

Improvement of saccadic functions after dosing with methadone in opioid addicted individuals

In the current experiment, we used the saccadometric test to study the effect of a single therapeutic dose of methadone on the integrity of cortico-subcortical brain functioning. In this prospective study, we used the Saccadometer System (Advanced Clinical Instrumentation, Cambridge, UK). The saccadometric test was performed before and 1.5 hours after methadone dosing. We analyzed the following saccadic parameters: latency, duration, amplitude, average and peak velocity, and processing performance (promptness) as well as a number of different types of saccades (like correct/incorrect, under/overshoot, and left-sided/right-sided). The sample consists of 40 subjects with an average 18 years of opioid addiction. The mean age is 35.3 ± 7 (80% males and 20% females). The mean period of heroin dependence is 15.3 ± 6.3 years. The mean daily dose of methadone in substitution therapy is 90 ± 26.5 mg. After administration of a single therapeutic dose of methadone, there were statistically significant differences in the values of saccade duration and latency when compared to the values before the drug administration. Average duration of saccade was significantly longer [51.40 ± 8.75 ms versus 48.93 ± 6.91 ms, z = 2.53, p = .01] and average latency was significantly longer [198.85 ± 52.57 ms versus 183.05 ± 30.95 ms, z = 2.09 p < .03]. This is the first study to test the therapeutic effect of daily methadone dosing on the integrity of the cortico-subcortical brain functions as measured by the saccadometry. More research is needed to explore the effect of illicit opioid use on the integrity of brain structures and functions, and the protective effect of opioid agonist therapy on reversing the damaging effects of illicit opioid use.

Usefulness of the measurement of saccadic refixation in the diagnosis of attention-deficit hyperactivity disorder/hyperkinetic disorder in adults

Background:

The aim of the research is to evaluate the usefulness of the measurement of saccadic refixation in the diagnosis of attention-deficit hyperactivity disorder (ADHD)/hyperkinetic disorder (HKD) in adults.

Methods:

Seventy-eight individuals were examined: 40 with ADHD/HKD and 38 healthy ones. A noninvasive eye movement examination using the Saccadometer (Advanced Clinical Instrumentation, Cambridge, UK) was applied. Two saccadic tests, prosaccades task (PT) and antisaccades task (AT), were carried out.

Results:

Based on the results, we can assume that selected parameters, such as latency, standard deviation of latency, promptness, and correctness (directional errors), in individuals with ADHD/HKD differ statistically in the relevant parameters from the healthy ones. The latency and the standard deviation of latency in ADHD/HKD participants are greater when compared to healthy ones. ADHD/HKD participants have a greater number of directional errors in comparison to healthy ones.

Conclusions:

The standard deviation of latency prosaccades is a good parameter for distinguishing people from both groups. An important and innovative solution in this study in comparison to the studies of other authors, who reached similar results, is the use of an automatically calibrating system (autonomous) adapted for clinical use as well as a quantitative analysis of the saccadic parameters.

Oculomotor disturbances in HIV-positive individuals treated with methadone

INTRODUCTION

Methadone substitution is claimed to be the most effective way of pharmacological management of human immunodeficiency virus (HIV) positive patients addicted to opioids. Possible and clinically the most relevant drug interactions are those between methadone and antiretroviral agents [13,18,25,32]. HIV causes cognitive impairment by infiltrating the central nervous system (CNS) in the initial phase of infection. The consequence of this is damage to the hippocampus, caudate nucleus, and basal ganglia [2,26].

METHODS

Eighty-six patients from the substitution program group were examined. The trial was conducted twice: before and about 1.5 hours after the administration of a therapeutic dose of methadone. The antisaccades task (AT) and latency task (LT) were performed using a saccadometer diagnostic system.

RESULTS

The statistical analysis showed that the mean duration of latency measured by AT in HIV(-) and HIV(+) subjects after the administration of a therapeutic dose of methadone was significantly increased (p=0.03 HIV(-); p=0.04 HIV(+)). There was a statistically significant increase in the mean latency after the administration of methadone in HIV(+) subjects when compared to the control group measured by LT (p=0.03).

CONCLUSION

The statistical analysis confirms the change in the saccadic refixation parameters in patients addicted to opioids. Methadone influences saccadic dynamic parameters less in HIV(+) than in HIV(-) drug users. Oculomotor disturbances are probably related to the neurotropic effects of HIV leading to damage of the striatum, which plays an important role in psychomotor functions.

Risk behavior in opioid-dependent individuals after the administration of a therapeutic dose of methadone

BACKGROUND AND OBJECTIVES

Evidence suggests that methadone may play a protective role in the faulty decision-making in heroin-addicted individuals. This may reduce craving for opioids and the risky decisions associated with active opioid use.

METHODS

We tested the effect of a daily therapeutic dose of methadone on faulty decision-making in eighty (n = 80) individuals with a history of opioid addiction. We used the Iowa Gambling Task (IGT) and compared the score and response time before and after the daily methadone dosing.

RESULTS

The mean net IGT score before methadone dose was 10 (±22) and 22 (±23) after methadone dose (t = 4.23, p = .00006). These results reflect statistically significant improvement in faulty decisions after the administration of the daily methadone dose. The mean response time for the reward cards before methadone dose were 1,856 ms (±871) and 1,465 ms (±851) after methadone dose (t = 2.55, p = .012). The mean response time for the punishment cards before methadone dose were 1,688 ms (±911) and 1,399 ms (±827) after methadone dose (t = 1.86, p = .065). These results reflect statistically significant improvement in response time to a rewarding healthy decisions after the administration of the daily methadone dose.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

This is the first study to report the effect of a therapeutic dose of methadone on improving faulty decisions for individuals with a long history of opioids addiction. This study demonstrated that the time to making a healthy decision was significantly shorter as a result of administration of methadone.

[Early postoperative assessment of cognitive functions after stereotactic pallidotomy in patients with primary dystonia - preliminary results]

BACKGROUND AND PURPOSE

The newest studies notify that globus pallidus, besides the motor control, plays an important role in cognitive functioning of: memory, attention, linguistic skills, visuospatial ability, and executive functions. Stereotactic pallidotomy (the lesion of the motor region of the globus pallidus) is one of the surgery options that is used in the treatment of the primary dystonia. Motor region is located in the postero-ventral part of the internal globus pallidus. The goal of the study was to assess of the influence of pallidotomy on cognitive functioning in the group of patients suffering from the primary dystonia.

MATERIAL AND METHODS

Eighteen patients diagnosed with primary dystonia were treated by stereotactic pallidotomy and they were investigated neuropsychologically. The study was performed between March 2004 and February 2005. Neuropsychological assessment was conducted 1-2 days prior to operation and 2 days following the surgery. The clinical course of the cognitive functions and emotional status were assessed by the following neuropsychological tests: Mini Mental State Examination (MMSE), Trail Making Test A and B (TMT A and B), Stroop Color-Word Interference Test, N-back Test, Auditory Verbal Learning Test (AVLT), Benton Visual Retention Test (BVRT), Wisconsin Card Sorting Test (WCST), Beck Depression Inventory (BDI), Montgomery-Asberg Depression Rating Scale (MADRS).

RESULTS

The statistically significant differences have been obtained between the results before and after the surgery in the depression scales: BDI (p<0.02) and in MADRS (p<0.01). None of the neuropsychological tests revealed significant differences between the results before and after the surgery. The only trend (p=0.06-0.07) was noted between results of AVLT before and after the surgery. The average results were worse after the surgery in the first, fifth and sixth attempt of the reply.

CONCLUSIONS

Stereotactic pallidotomy has not significantly changed cognitive functions in the patients suffering from primary dystonia. Whereas, the emotional state has significantly improved in consequence of the applying surgery. Stereotactic pallidotomy in primary dystonia seems to be a treatment option safe for the patients' cognitive functions.

Two components of long-term memory

The existence of two independent components of long-term memory has been demonstrated by the authors. The evidence has been derived from the authors' findings related to the optimum spacing of repetitions in paired-associate learning. The two components are sufficient to explain the optimum spacing of repetitions as well as the spacing effect. Although the molecular counterparts of the two components of memory are not known, the authors provide a collection of guidelines that might facilitate identification of such counterparts.

A hypothetical model of processes involved in the release of norepinephrine in the adrenergic synapse

A hypothetical, conceptual model of mechanisms involved in the release of norepinephrine in the adrenergic synapse is presented. An illustrative, mathematical equivalent of the model was constructed to enable computer simulation of the considered processes in varying cytophysiological conditions. The mathematical model has the form of a set of equations that make it possible to compute the state of the system at the moment t + delta t on the basis of the state at the moment t.