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Individual differences in cognitive performance are partly dependent, on genetic polymporhisms. One of the single-nucleotide polymorphisms (SNP) of the CNR1 gene, which codes for cannabinoid receptor 1 (CB1R), is the rs2180619, located in a regulatory region of this gene (6q14-q15). The alleles of the rs2180619 are A > G; the G allele has been associated with addiction and high levels of anxiety (when the G allele interacts with the SS genotype of the 5-HTTLPR gene). However, GG genotype is observed also in healthy subjects. Considering G allele as risk for 'psychopathological conditions', it is possible that GG healthy subjects do not be addicted or anxious, but would have reduced performance, compared to AA subjects, in attentional control and working memory processing. One hundred and sixty-four healthy young Mexican-Mestizo subjects (100 women and 64, men; mean age: 22.86 years, SD=2.72) participated in this study, solving a task where attentional control and working memory were required. GG subjects, compared to AA subjects showed: (1) a general lower performance in the task (P = 0.02); (2) lower performance only when a high load of information was held in working memory (P = 0.02); and (3) a higher vulnerability to distractors (P = 0.03). Our results suggest that, although the performance of GG subjects was at normal levels, a lower efficiency of the endocannabinoid system, probably due to a lowered expression of CB1R, produced a reduction in the performance of these subjects when attentional control and working memory processing is challenged.

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The primary aim of the present study was to test diazepam (DZ) effect, a benzodiazepine (BDZ) usually prescribed to reduce anxiety and to induce sleep, on EEG activity while performing a visual sustained attention task. The EEG activity was recorded in a double-blind placebo experiment, and prestimulus spectral power and inter- and intrahemispheric temporal coupling were assessed during visual sustained attention task performance. A single DZ dose (5 mg) was enough to increase reaction times during visual sustained attention task responses. DZ decreased prestimulus EEG power in the 1- to 6-, 8- to 12-, and 19- to 35-Hz bands and disrupted right intrahemispheric temporal coupling in the α-frequency range (8-12 Hz). The combined reduction in power and temporal coupling suggests both local and interregional DZ-induced disruption of neuronal synchronicity especially in the right hemisphere in agreement with the prominent attention-related networks in this hemisphere. These data support the notion that the influence of DZ on behavior goes beyond sedative effects and can potentially compromise higher cognitive functions with negative consequences to daily life situations.