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Take it or leave it: prefrontal control in recreational cocaine users.

Morein-Zamir S, Simon Jones P, Bullmore ET, Robbins TW, Ersche KD - Transl Psychiatry (2015)

Bottom Line: Results revealed that recreational cocaine users did not significantly differ from controls on any index of task performance, including response execution and stop-signal reaction time, with the latter averaging 198 ms in both groups.Thus, findings imply intact response inhibition abilities in recreational cocaine users, though the distinct pattern of accompanying activation suggests increased recruitment of brain areas implicated in response inhibition.Such overactivation, alternatively, may be attributable to prolonged cocaine use leading to neuroplastic adaptations.

View Article: PubMed Central - PubMed

Affiliation: 1] Behavioural and Clinical Neuroscience Institute, Department of Psychology, University of Cambridge, Cambridge, UK [2] Department of Psychology, University of Cambridge, Cambridge, UK [3] Department of Psychology, Anglia Ruskin University, Cambridge, UK.

ABSTRACT
Though stimulant drugs such as cocaine are considered highly addictive, some individuals report recreational use over long periods without developing dependence. Difficulties in response inhibition have been hypothesized to contribute to dependence, but previous studies investigating response inhibition in recreational cocaine users have reported conflicting results. Performance on a stop-signal task was examined in 24 recreational cocaine users and 32 healthy non-drug using control participants matched for age, gender and verbal intelligence during functional magnetic resonance imaging scanning. The two groups were further matched on traumatic childhood histories and the absence of family histories of addiction. Results revealed that recreational cocaine users did not significantly differ from controls on any index of task performance, including response execution and stop-signal reaction time, with the latter averaging 198 ms in both groups. Functional magnetic resonance imaging analyses indicated that, compared with controls, stopping in the recreational users was associated with increased activation in the pre-supplementary motor area but not the right inferior frontal cortex. Thus, findings imply intact response inhibition abilities in recreational cocaine users, though the distinct pattern of accompanying activation suggests increased recruitment of brain areas implicated in response inhibition. This increased recruitment could be attributed to compensatory mechanisms that enable preserved cognitive control in this group, possibly relating to their hypothetical resilience to stimulant drug dependence. Such overactivation, alternatively, may be attributable to prolonged cocaine use leading to neuroplastic adaptations.

No MeSH data available.


Related in: MedlinePlus

Significant brain activation maps associated with stopping in each group separately. (a) Denotes lateral and medial views of recreational cocaine users. (b) Denotes lateral and medial views of healthy volunteers. P<0.001 uncorrected, for illustration purposes only.
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fig1: Significant brain activation maps associated with stopping in each group separately. (a) Denotes lateral and medial views of recreational cocaine users. (b) Denotes lateral and medial views of healthy volunteers. P<0.001 uncorrected, for illustration purposes only.

Mentions: Each group demonstrated activation in regions commonly observed in this task for stopping in whole brain analyses corrected for family-wise error, P<0.05. These included the vlPFC, encompassing the anterior insula and IFG predominantly on the right, in addition to the dmPFC, superior inferior parietal cortex and occipital cortex bilaterally (see Figure 1). Visual inspection suggested greater and more extensive activation in recreational users compared with controls during stopping. In accordance with this conclusion, the anatomical region of interest analyses indicated overactivation in recreational users compared with the controls in stopping versus going in the right pre-SMA (P=0.048, [10,20,46], cluster extent (KE)=8, Z=3.23). In addition, there was increased activation in the right ACC (P=0.028, [−2,26,30], KE=24, Z=3.58) and left ACC (P=0.047, [4,24,18], KE=14, Z=3.58) for stopping. These results remained when covarying for alcohol and tobacco consumption (see Supplementary Information for additional details). There was no significant group difference in the vlPFC region of interest. In addition, no group differences were noted in failed versus successful stopping (see Supplementary Information for additional details). Recreational drug users showed increased activation in the response override search area (t(54)=1.86, Contrast Value 0.96, P=0.034), though both groups showed significant activation compared with the go baseline (t(31)=4.43, P<0.001 and t(23)=6.45, P<0.001 for controls and recreational users, respectively). SSRT did not correlate significantly with any functional activation or group characteristic. In sum, recreational users showed increased activation not only in the pre-SMA but also more general widespread activation in areas associated with suppressing prepotent responses compared with controls.


Take it or leave it: prefrontal control in recreational cocaine users.

Morein-Zamir S, Simon Jones P, Bullmore ET, Robbins TW, Ersche KD - Transl Psychiatry (2015)

Significant brain activation maps associated with stopping in each group separately. (a) Denotes lateral and medial views of recreational cocaine users. (b) Denotes lateral and medial views of healthy volunteers. P<0.001 uncorrected, for illustration purposes only.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490290&req=5

fig1: Significant brain activation maps associated with stopping in each group separately. (a) Denotes lateral and medial views of recreational cocaine users. (b) Denotes lateral and medial views of healthy volunteers. P<0.001 uncorrected, for illustration purposes only.
Mentions: Each group demonstrated activation in regions commonly observed in this task for stopping in whole brain analyses corrected for family-wise error, P<0.05. These included the vlPFC, encompassing the anterior insula and IFG predominantly on the right, in addition to the dmPFC, superior inferior parietal cortex and occipital cortex bilaterally (see Figure 1). Visual inspection suggested greater and more extensive activation in recreational users compared with controls during stopping. In accordance with this conclusion, the anatomical region of interest analyses indicated overactivation in recreational users compared with the controls in stopping versus going in the right pre-SMA (P=0.048, [10,20,46], cluster extent (KE)=8, Z=3.23). In addition, there was increased activation in the right ACC (P=0.028, [−2,26,30], KE=24, Z=3.58) and left ACC (P=0.047, [4,24,18], KE=14, Z=3.58) for stopping. These results remained when covarying for alcohol and tobacco consumption (see Supplementary Information for additional details). There was no significant group difference in the vlPFC region of interest. In addition, no group differences were noted in failed versus successful stopping (see Supplementary Information for additional details). Recreational drug users showed increased activation in the response override search area (t(54)=1.86, Contrast Value 0.96, P=0.034), though both groups showed significant activation compared with the go baseline (t(31)=4.43, P<0.001 and t(23)=6.45, P<0.001 for controls and recreational users, respectively). SSRT did not correlate significantly with any functional activation or group characteristic. In sum, recreational users showed increased activation not only in the pre-SMA but also more general widespread activation in areas associated with suppressing prepotent responses compared with controls.

Bottom Line: Results revealed that recreational cocaine users did not significantly differ from controls on any index of task performance, including response execution and stop-signal reaction time, with the latter averaging 198 ms in both groups.Thus, findings imply intact response inhibition abilities in recreational cocaine users, though the distinct pattern of accompanying activation suggests increased recruitment of brain areas implicated in response inhibition.Such overactivation, alternatively, may be attributable to prolonged cocaine use leading to neuroplastic adaptations.

View Article: PubMed Central - PubMed

Affiliation: 1] Behavioural and Clinical Neuroscience Institute, Department of Psychology, University of Cambridge, Cambridge, UK [2] Department of Psychology, University of Cambridge, Cambridge, UK [3] Department of Psychology, Anglia Ruskin University, Cambridge, UK.

ABSTRACT
Though stimulant drugs such as cocaine are considered highly addictive, some individuals report recreational use over long periods without developing dependence. Difficulties in response inhibition have been hypothesized to contribute to dependence, but previous studies investigating response inhibition in recreational cocaine users have reported conflicting results. Performance on a stop-signal task was examined in 24 recreational cocaine users and 32 healthy non-drug using control participants matched for age, gender and verbal intelligence during functional magnetic resonance imaging scanning. The two groups were further matched on traumatic childhood histories and the absence of family histories of addiction. Results revealed that recreational cocaine users did not significantly differ from controls on any index of task performance, including response execution and stop-signal reaction time, with the latter averaging 198 ms in both groups. Functional magnetic resonance imaging analyses indicated that, compared with controls, stopping in the recreational users was associated with increased activation in the pre-supplementary motor area but not the right inferior frontal cortex. Thus, findings imply intact response inhibition abilities in recreational cocaine users, though the distinct pattern of accompanying activation suggests increased recruitment of brain areas implicated in response inhibition. This increased recruitment could be attributed to compensatory mechanisms that enable preserved cognitive control in this group, possibly relating to their hypothetical resilience to stimulant drug dependence. Such overactivation, alternatively, may be attributable to prolonged cocaine use leading to neuroplastic adaptations.

No MeSH data available.


Related in: MedlinePlus