Chronic effects of cannabis on sensory gating

Abstract

Chronic cannabis use has been associated with neurocognitive deficits, alterations in brain structure and function, and with psychosis. This study investigated the effects of chronic cannabis use on P50 sensory-gating in regular users, and explored the association between sensory gating, cannabis use history and the development of psychotic-like symptoms. Twenty controls and 21 regular cannabis users completed a P50 paired-click (S1 and S2) paradigm with an inter-pair interval of 9. s. The groups were compared on P50 amplitude to S1 and S2, P50 ratio (S2/S1) and P50 difference score (S1-S2). While cannabis users overall did not differ from controls on P50 measures, prolonged duration of regular use was associated with greater impairment in sensory gating as indexed by both P50 ratio and difference scores (including after controlling for tobacco use). Long-term cannabis users were found to have worse sensory gating ratios and difference scores compared to short-term users and controls. P50 metrics did not correlate significantly with any measure of psychotic-like symptoms in cannabis users. These results suggest that prolonged exposure to cannabis results in impaired P50 sensory-gating in long-term cannabis users. While it is possible that these deficits may have pre-dated cannabis use and reflect a vulnerability to cannabis use, their association with increasing years of cannabis use suggests that this is not the case. Impaired P50 sensory-gating ratios have also been reported in patients with schizophrenia and may indicate a similar underlying pathology.

Abnormal medial prefrontal cortex activity in heavy cannabis users during conscious emotional evaluation

“…Furthermore, in controls, but not cannabis users, greater mPFC function while evaluating affective feedback predicted greater learning on the task (Wesley et al 2011). Impaired affective mPFC signal integration may also help explain other reports of impaired learning and mental flexibility in cannabis users (Lundqvist 2005; Kedzior and Martin-Iverson 2006; Solowij and Battisti 2008; Scholes and Martin-Iverson 2009; Battisti et al 2010a; Battisti et al 2010b; Broyd et al 2013). …”

Cannabinoids differentially modulate cortical information transmission through the sensorimotor or medial prefrontal basal ganglia circuits

“…Abnormal functionality of these circuits has been described in motor and behavioural disorders and cognitive deficits (for review, see Tremblay, Worbe, Thobois, Sgambato‐Faure, & Féger, ), and it has been related to the mechanism of action of some drugs, such as cannabinoids that also affect motor and cognitive functions. The use of cannabis is associated with deficits in working memory and decision making (related to mPF circuitry functionality; Grant, Gonzalez, Carey, Natarajan, & Wolfson, ; Schreiner & Dunn, ; Solowij & Battisti, ), as well as with alterations in sensory perception or impaired SM gating (related to dysfunctional processing in SM circuits; Broyd et al, ; Edwards, Skosnik, Steinmetz, O'Donnell, & Hetrick, ).…”

State-Dependent Changes in Auditory Sensory Gating in Different Cortical Areas in Rats

“…Sensory gating, a process in which the brain’s response to a repetitive stimulus is attenuated, is thought to contribute to information processing by enabling organisms to filter extraneous sensory inputs from the environment. To date, sensory gating has typically been used to determine whether brain function is impaired in response to an environmental stimulus, such as in individuals with schizophrenia or addiction [ 1 – 6 ]. Sensory gating can be adequately assessed using the sound stimuli of a Conditioning-testing paradigm, in which two identical auditory tones are presented 500 ms apart.…”