Aging, Smoking and Hemispheric EEG Asymmetry

Resting-state EEG, Substance use and Abstinence After Chronic use: A Systematic Review

Resting-state EEG reflects intrinsic brain activity and its alteration represents changes in cognition that are related to neuropathology. Thereby, it provides a way of revealing the neurocognitive mechanisms underpinning chronic substance use. In addition, it is documented that some neurocognitive functions can recover following sustained abstinence. We present a systematic review to synthesize how chronic substance use is associated with resting-state EEG alterations and whether these spontaneously recover from abstinence. A literature search in Medline, PsycINFO, Embase, CINAHL, Web of Science, and Scopus resulted in 4088 articles, of which 57 were included for evaluation. It covered the substance of alcohol (18), tobacco (14), cannabis (8), cocaine (6), opioids (4), methamphetamine (4), and ecstasy (4). EEG analysis methods included spectral power, functional connectivity, and network analyses. It was found that long-term substance use with or without substance use disorder diagnosis was associated with broad intrinsic neural activity alterations, which were usually expressed as neural hyperactivation and decreased neural communication between brain regions. Some studies found the use of alcohol, tobacco, cocaine, cannabis, and methamphetamine was positively correlated with these changes. These alterations can partly recover from abstinence, which differed between drugs and may reflect their neurotoxic degree. Moderating factors that may explain results inconsistency are discussed. In sum, resting-state EEG may act as a potential biomarker of neurotoxic effects of chronic substance use. Recovery effects awaits replication in larger samples with prolonged abstinence. Balanced sex ratio, enlarged sample size, advanced EEG analysis methods, and transparent reporting are recommended for future studies.

Dopamine receptor (DRD2) genotype‐dependent effects of nicotine on attention and distraction during rapid visual information processing

The effects of nicotine, distractor type, and dopamine type-2 receptor (DRD2) genotype on rapid visual information processing (RVIP) task performance were assessed in habitual smokers. Four RVIP tasks differed in terms of distractor location (central vs. peripheral) and distractor type (numeric vs. emotional). Each participant performed each of the tasks on two different days, once while wearing an active nicotine patch and once while wearing a placebo patch. Overall, the nicotine patch produced more accurate detection of and faster reaction times to target sequences; however, these effects varied with distractor type and genotype. Nicotine speeded reaction time more with left-visual-field (LVF) than right-visual-field (RVF) emotional distractors but speeded reaction time more with RVF than LVF numeric distractors, especially when the distractor digit matched the target sequence in terms of numeric oddness or evenness. Nicotine tended to facilitate performance more in individuals with at least one A1 allele than in homozygous A2A2 individuals, especially with numeric distractors presented to the left hemisphere. Nicotine tended to reduce distraction by negative stimuli more than other types of stimuli. Few gender differences were observed. The overall pattern of results was consistent with the view that nicotine modulates selective attention or subsequent information processing in a manner that depends partly on the emotional versus numeric nature of task distractors, DRD2 genotype, and the brain hemisphere that initially processes the distractors (visual field of distractor).

Electroencephalographic characterization of cigarette smoking behavior

The rewarding properties of used and abused substances are related to their ability to modulate central processes subserving mood, cognition, and behavior. Research into the motivationally relevant factors mediating substance use and abuse among human beings, including tobacco smoking, can strategically benefit from the utilization of noninvasive brain function measures that are able to probe the neurobiology of brain states in concert with substance ingestion. This paper reviews investigations from my laboratory with the use of neuroelectric tools, by means of quantitative electroencephalography, for the purpose of characterizing the central response to cigarette smoking. Prominent in these strategies is the acute smoking paradigm, whereby measures are focused on the profiling of central responsivity to smoke inhalation from a single cigarette and administration of test doses of nicotine. Complementing this approach are studies (1) in which receptor antagonists are administered in an attempt to explore putative transmitter systems regulating the acute smoking-induced electroencephalographic response and (2) in which electroencephalographic profiles of acute smoking are compared with electroencephalographic profiles resulting from administration of single doses of psychotropic substances. Completing these studies are attempts to monitor the electrocortical correlates of repeated smoking exposure and smoking deprivation, which, together with investigations examining smoker vs. nonsmoker differences and the effects of chronic life-long smoking, provide objective insights into the neuroelectrophysiology underlying the smoking habit.