Auditory-Evoked Potentials and Selective Attention: Different Ways of Information Processing in Cannabis Users and Controls

Abstract

The present study tested the hypothesis that chronic cannabis use leads to persistent attentional dysfunctions and that age of onset of cannabis use is a potential predictor of impaired test performance and information processing. Brain event-related potentials (ERPs) during a complex auditory selective attention task were recorded from 21 cannabis users divided into two groups according to age of onset and from 13 controls comparable with respect to age, IQ and educational background. Participants were instructed to detect target tones of a particular location, pitch and duration from a total sample of random frequencies. The study reveals that the latency of the greatest negative peak of ERPs (200 and 300 ms) to target tones was shorter in controls, while there was no clear difference between target and non-target within cannabis users. In addition, users displayed a reduced P₃ to target tones. This was more pronounced in early-onset cannabis users. These data suggest that chronic cannabis use relates to different types of information processing under conditions of selective attention. There is some evidence that users employed different strategies of attention allocation. The results are discussed with respect to possible underlying mechanisms and clinical implications.

Neuropsychological functioning in adolescent marijuana users: Subtle deficits detectable after a month of abstinence

“…For example, introduction of cannabis during adolescence may interrupt pruning of gray matter or disruption of white matter myelination, especially in the prefrontal cortex (Block et al, 2002;Egerton et al, 2006;Lundqvist et al, 2001), which continues to develop into early adulthood (Gogtay et al, 2004;Lenroot & Giedd, 2006;Nagel et al, 2006;Sowell et al, 2004). The current findings are consistent with animal studies that found more severe cannabis-induced learning impairments among adolescents compared with adults (Cha et al, 2006;Schneider & Koch, 2003;Stiglick & Kalant, 1982, 1985 and findings that early onset use is associated with increased morphometric, electrophysiological, and cognitive abnormalities among adult marijuana users (Ehrenreich et al, 1999;Kempel et al, 2003;Pope et al, 2003;Wilson et al, 2000). It is unknown whether continued abstinence from marijuana results in neurocognitive recovery or subsequent healthy neurodevelopment among adolescents.…”

Cannabinoid receptors are localized to noradrenergic axon terminals in the rat frontal cortex

“…Long-term heavy cannabis users show impairments in attention that endure beyond the period of intoxication and worsen with increasing years of regular cannabis administration (Solowij, Stephens et al 2002). Studies examining the effects of cannabinoids on attention, utilizing a combination of performance and event-related potential measures, have shown that chronic cannabis use affects information processing (Kempel, Lampe et al 2003). Specifically, cannabis consumers are unable to filter out extraneous information and there is an inability to effectively focus attention and reject irrelevant information (Solowij, Michie et al 1995).…”

fMRI response to spatial working memory in adolescents with comorbid marijuana and alcohol use disorders

“…A longitudinal study of marijuana dependent adolescents demonstrated further shortterm memory decrements that persisted after 6 weeks of monitored abstinence (Schwartz et al, 1989). In addition, compared to individuals with adult-onset cannabis use disorder and nonabusing controls, adolescent-onset cannabis use disordered adults showed attenuated electrophysiological response during selective attention (Kempel et al, 2003), as well as smaller frontal and parietal volumes and increased cerebral blood flow (Wilson et al, 2000). These studies indicate that heavy marijuana use during youth may adversely affect cognition and brain functioning, particularly short-term memory and attention, and raise questions about the integrity of frontal and parietal brain regions in adolescents with marijuana use disorders.…”