Abstract
High levels of trait impulsivity are considered a risk factor for substance abuse and drug addiction. We recently found that non-planning trait impulsivity was negatively correlated with post-commissural putamen volumes in men, but not women, using the Karolinska Scales of Personality (KSP). Here, we attempted to replicate this finding in an independent sample using an updated version of the KSP: the Swedish Universities Scales of Personality (SSP). Data from 88 healthy male participants (Mean Age: 28.16±3.34), who provided structural T1-weighted magnetic resonance images (MRIs) and self-reported SSP impulsivity scores, were analyzed. Striatal sub-region volumes were acquired using the Multiple Automatically Generated Templates (MAGeT-Brain) algorithm. Contrary to our previous findings trait impulsivity measured using SSP was not a significant predictor of post-commissural putamen volumes (β = .14, df = 84, p = .94). A replication Bayes Factors analysis strongly supported this null result. Consistent with our previous findings, secondary exploratory analyses found no relationship between ventral striatum volumes and SSP trait impulsivity (β = -.05, df = 84, p = .28). An exploratory analysis of the other striatal compartments showed that there were no significant associations with trait impulsivity. While we could not replicate our previous findings in the current sample, we believe this work will aide future studies aimed at establishing meaningful brain biomarkers for addiction vulnerability in healthy humans.
Highlights
Heightened impulsivity is considered both a risk factor for, and a consequence of, chronic substance abuse and drug addiction [1,2,3]
Contrary to our previous findings [29], trait impulsivity measured by the Scales of Personality (SSP) was not a significant predictor of post-commissural putamen volumes (β = .14, df = 84, p = .94) (Table 2 & Fig 2)
Replication Bayes Factor (BF) showed that the data was over 607 times more likely to have occurred under H0, compared to under that of the posterior distribution of the original study, i.e. a strong negative relationship between trait impulsivity and post-commissural putamen volume (Fig 3)
Summary
Heightened impulsivity is considered both a risk factor for, and a consequence of, chronic substance abuse and drug addiction [1,2,3]. Impulsivity is a multidimensional construct, encompassing impulsive choice, impulsive action, and self-reported impulsive personality traits [4]. While studies have not observed strong relationships between measures of impulsive choice and impulsive action, both are weakly correlated with measures of trait impulsivity [4,5,6].
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