Brain response to different message content of pictorial health warnings from tobacco packages: comparison between smokers and non-smokers using fMRI
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Date
2018-10
Authors
Lee, Cheeh Hui
Journal Title
Journal ISSN
Volume Title
Publisher
Pusat Pengajian Sains Perubatan, Universiti Sains Malaysia
Abstract
The effectiveness of the Pictorial Health Warnings Labels (PHWLs) from the tobacco packages
in tobacco control remains controversial. To date, there is lacking of functional magnetic
resonance imaging (fMRI) studies on the message content of the labels with different value
emphasis. These values are the crucial components in the cigarette related decision making.
In this study, the brain activation of the smokers and non-smokers from the young age group
in response to PHWLs themes (Cosmetic Consequences “COS”, Endanger Others “EN”,
Negative Lifestyle “NE” as well as Disease and Death “DD” were investigated. To ensure the
adequacy of the labels in evoking desired affective states, an online normative rating
questionnaire was completed by 100 respondents to obtain valence and arousal values for each
PHWLs themes. One-way repeated measures ANOVA (p < 0.05) revealed that all PHWLs
themes were rated significantly more unpleasant and arousing than the control (Natural “NA”)
images, except NE on the arousal dimension. Followed by that, 10 smokers and 10 nonsmokers
lied inside an MRI machine to view a series of images that categorized into different
themes. Blood-oxygenated-level-dependent responses during the fMRI task were captured to
examine the brain activation in response to the PHWLs themes between the groups in terms of
spatial extent. As revealed from the random-effects analyses (2 x 5 mixed ANOVA) with
Puncorrected < 0.001, a widespread of regions that associated with cognitive and affective
functioning were recruited by smokers and non-smokers during the PHWLs viewing task, with
or without taking the smoking status into consideration. Left middle temporal gyrus (associated
with information integration) was activated when both groups viewing images of all themes.
Regardless of the smoking status, visual related activation (i.e. inferior occipital gyrus (IOG),
inferior temporal gyrus) were evoked by images of PHWLs themes with relatively similar
extent while limbic related activation (i.e. right amygdala) were evoked by DD images in
relative to NA images. Several new findings were noted. Firstly, greater brain activation wasobserved in regions associated salient stimulus detection (i.e. right inferior parietal gyrus, left
middle frontal gyrus (MFG)) to COS images compared to EN images in smokers, social
perception (i.e. left precentral gyrus (PG), left IOG) to EN images compared to NA images in
both groups or regardless of smoking status, metaphor comprehension (i.e. left inferior frontal
gyrus (IFG)) to NE images compared to EN images in smokers and strong emotional
processing (i.e. right amygdala) to DD images compared to NA images irrespective of smoking
status. Secondly, activation associated with emotional regulation (left PG) in response to EN
and DD images compared to NA images was absent in smokers only. Thirdly, activation
associated with salient stimulus detection and attentional processing in response to COS images
compared to EN images was observed in smokers only. Fourthly, medial frontal activation that
associated with self-related processing were exhibited by smokers more to COS and DD images
in relative to other themes, with or without the consideration of smoking status. However, such
activation was more responsive to COS than DD images for smokers. Fifthly, significant
greater percent signal change (PSC) in the right IFG that associated with inhibitory control
processing was observed when smokers and non-smokers viewing the NE images in relative to
NA and COS images respectively as revealed from the dependent t-test and Wilcoxon-Signed
Rank tests (p < 0.05) in the examination of brain activation in terms of intensity. Based on
these new findings, several conclusions were made. Firstly, the main characteristics of each
PHWLs theme might be reflected as the following: the salient feature of the COS images, the
social aspect of smoking of the EN images, the symbolic nature of the NE images and the
emotionally salient feature of the DD images. Secondly, desensitization towards the commonly
known smoking risk (health issues and passive smoker) might have taken place in smokers
only, underscoring the needs to address these smoking risk in a novel way. Thirdly, young
smokers might have more concern about the smoking effect on their physical attributes than
their health. The relevance of this message content type is supported with more attention givenby the smokers only to COS than EN images. These findings suggest that COS could be the
ideal messages to reach to the young smokers effectively. Lastly, the inadequacy of the NE
images in achieving effective message communication underscores the needs to refine the
design of this message content type.
Description
Keywords
Smoking prevention