Individual differences in brain responses to cigarette-related cues and pleasant stimuli in young smokers

Abstract

Background: Decreased sensitivity to pleasant stimuli is associated with a higher vulnerability to nicotine dependence in youths and with difficulty quitting in adult smokers. Recently, we showed that smokers showing lower brain reactivity to non-cigarette-related pleasant images than to cigarette-related ones have lower chances of achieving long-term abstinence during a quit attempt.

Methods: We tested whether individual differences in brain responses to cigarette-related and pleasant stimuli require a long history of smoking to develop by measuring the late positive potential (LPP) to cigarette cues, emotional, and neutral stimuli in 45 young, light smokers (ages 18-25). k-means cluster analysis was used to partition smokers into two groups based on the magnitude of their LPPs.

Results: Group 1 was characterized by larger LPPs to pleasant pictures than cigarette-related pictures whereas Group 2 showed the opposite pattern.

Conclusions: Our results suggest that individual differences in brain responses to cigarette-related and pleasant cues do not require a long smoking history to develop.

Keywords: Addiction; Emotion; Smoking; Young adults.

Figure 1

The time window for computing the LPP was identified via permutation testing. Upper traces, left vertical axis: Grand-average event-related potential (ERP) at Cz in response to cigarette-related (CIG), pleasant (PLE), neutral (NEU), and unpleasant (UNP) pictures. Time is plotted on the horizontal axis, where stimulus onset occurred at 0 ms. Lower trace (Observed F), right vertical axis: F-statistic for the effect of picture category observed at each time point. The dashed horizontal line indicates the threshold for identifying time points with significant effects of picture category. This value (F > 5.5) was obtained using a permutation-based statistical testing approach (for details, see Statistical Analysis). The dashed vertical lines illustrate the time window (520-848 ms) used to compute the LPP magnitude.

Figure 2

Magnitude of the late positive potential (LPP) at Cz in response to cigarette-related (CIG), pleasant (PLE), neutral (NEU), and unpleasant (UNP) pictures in young smokers who were classified into two groups using k-means cluster analysis. For Group 1, n = 20. For Group 2, n = 25. * = p < .05 for the within-group difference between cigarette-related and pleasant pictures (Bonferroni-corrected for all pairwise comparisons).

Figure 3

Magnitude of the late positive potential (LPP) at Cz in response to cigarette-related (CIG), pleasant (PLE), neutral (NEU), and unpleasant (UNP) pictures in a reference group of non-smokers, plotted on the same scale as that used for smokers (see Figure 2).