Psychopharmacology DOI 10.1007/s00213-014-3483-8
ORIGINAL INVESTIGATION
Volumetric differences in the anterior cingulate cortex prospectively predict alcohol-related problems in adolescence Ali Cheetham & Nicholas B. Allen & Sarah Whittle & Julian Simmons & Murat Yücel & Dan I. Lubman
Received: 11 June 2013 / Accepted: 3 February 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Rationale Individual differences in brain structure and function are suggested to exist prior to the onset of alcohol abuse. Cross-sectional studies have demonstrated abnormalities in brain regions underlying affective processes that may form a pathway to the emergence of later alcohol abuse and dependence in vulnerable individuals. However, no prospective studies have examined whether these abnormalities predict later problems with alcohol. Objective This study aims to examine whether individual differences in affect and brain volume prospectively predict alcohol-related problems in adolescence. Method Adolescent drinkers (n=98) were recruited from an ongoing prospective, longitudinal study examining adolescent emotional development. At age 12, participants underwent structural magnetic resonance imaging to obtain volumetric data on the amygdala, hippocampus, orbitofrontal cortex, and A. Cheetham : N. B. Allen : S. Whittle : J. Simmons Orygen Youth Health Research Centre, Centre for Youth Mental Health, The University of Melbourne, Melbourne, VIC, Australia A. Cheetham : D. I. Lubman (*) Turning Point Alcohol and Drug Centre, Eastern Health and Monash University, Melbourne, VIC, Australia e-mail: [email protected] N. B. Allen : J. Simmons Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, VIC, Australia S. Whittle : M. Yücel Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Melbourne, VIC, Australia M. Yücel Monash Clinical and Imaging Neuroscience, School of Psychology and Psychiatry, Monash University, Melbourne, VIC, Australia
anterior cingulate cortex (ACC), and completed a self-report measure of affective temperament. At age 16, participants completed a questionnaire measuring alcohol use, with 39 % reporting alcohol-related problems in the past year. Results Pre-existing differences in the left ACC predicted problem drinking. Alcohol-related problems were associated with higher levels of temperamental negative affectivity; however, these were not correlated with anterior cingulate volumes. Conclusions These findings indicate that individual differences in the structural morphology of the anterior cingulate, a region implicated in affective processes, self-control, and drug addiction, predict later alcohol-related problems. Although this finding remained significant after controlling for other substance use and psychopathology, future research is required to test its specificity for alcohol use disorders. Keywords Alcohol . Adolescence . Structural MRI . Anterior cingulate . Affect
Introduction Alcohol abuse makes a substantial contribution to preventable mortality and morbidity worldwide, particularly amongst adolescents and young adults (Ezzati et al. 2002; Rehm et al. 2009). The adolescent brain is thought to be particularly vulnerable to the effects of alcohol, due to ongoing processes of brain maturation that involve substantial remodelling of regions involved in affective, cognitive, and behavioural regulation (Crews et al. 2007; Lubman et al. 2007a; Nixon and McClain 2010). Accordingly, there is growing evidence that alcohol abuse and dependence during adolescence are associated with structural brain abnormalities, particularly in prefrontal and temporal regions (see Bava and Tapert 2010, for a review). However, while these
Psychopharmacology
regions may be sensitive to the effects of alcohol during adolescence, it is also possible that deficits or developmental delays in the maturation of some structures influence risk for problematic alcohol use during this period. As such, it is not clear whether abnormalities observed in studies of adolescents with alcohol use disorders reflect neurotoxicity associated with heavy alcohol use or premorbid vulnerability factors that increase risk for such disorders. Few studies have prospectively examined the neuroanatomical predictors of problematic alcohol use. Amongst adolescents with minimal use, altered activation in regions involved in response inhibition and working memory have been found to predict the initiation of heavy drinking (Wetherill et al. 2013; Norman et al. 2011; Squeglia et al. 2012). In addition, a recent study by Jacobus et al. (2013) found differences in white matter integrity between adolescents who went on to initiate heavy alcohol use and adolescents who went on to initiate both heavy alcohol and cannabis use, although no comparisons were made with nonsubstance-using controls. To our knowledge, no other studies have prospectively examined whether structural differences exist before the onset of heavy alcohol use. However, cross-sectional research examining the offspring of alcoholics has provided evidence that some abnormalities in brain structure and function may exist prior to the onset of alcohol abuse or dependence. Relative to healthy controls, individuals considered to be at high genetic risk for alcoholism have been found to demonstrate smaller volumes of the frontal cortex (Benegal et al. 2006; Hill et al. 2009) and amygdala (Hill et al. 2001; Benegal et al. 2006), both smaller (Benegal et al. 2006; Sjoerds et al. 2013) and larger (Hanson et al. 2010) volumes of the hippocampus and parahippocampal gyri, as well as altered white matter microstructure in tracts connecting prefrontal to cortical, striatal, and cerebellar regions (Herting et al. 2011; Herting et al. 2010). In addition, functional imaging studies have found altered activity in regions implicated in reward processing and cognitive control, including the amygdala (Glahn et al. 2007; Heitzeg et al. 2008), anterior cingulate cortex (ACC), and medial prefrontal regions (Acheson et al. 2009; Spadoni et al. 2008; Silveri et al. 2011; Kareken et al. 2010; Hill et al. 2007; Heitzeg et al. 2008; Heitzeg et al. 2010). While this field is still in its infancy, these studies provide evidence that individuals at risk for alcoholism demonstrate abnormalities in brain structure and function in the absence of any clinically significant problems with alcohol. The current study aimed to add to this literature by examining whether individual differences in brain volume could prospectively predict the experience of alcohol-related problems in a sample of healthy adolescents. In addition, we examined the influence of affective temperament on alcohol-
related problems in the same sample. There is considerable evidence that individual differences in affective functioning (i.e., the processes by which emotions are generated, maintained, and managed) are associated with the abuse of alcohol and other substances, regardless of whether a positive family history of alcoholism is present (Cheetham et al. 2010). In particular, negative affect (NA) has been frequently linked to indices of problematic alcohol use in adolescence and young adulthood. This includes evidence supporting a relationship between high trait negative affectivity and alcohol-related problems in community samples (e.g., Stewart et al. 2001), as well as the co-occurrence of alcohol use disorders with affective psychopathology (i.e., mood and anxiety disorders; Kushner et al. 2000; Page and Andrews 1996; Schuckit et al. 1997). Indeed, while drinking in response to negative affect does not appear to be a consistent predictor of alcohol use itself, it is frequently associated with alcohol-related problems during adolescence (e.g., Merrill and Read 2010; Simons et al. 2005; Kassel et al. 2000; Gaher et al. 2006). Affect regulation, which can refer to both the regulation of internal affective states as well as the control of overt behaviours driven by affective processes (Eisenberg et al. 2000), is also likely to be associated with problematic alcohol use during this period. Poor regulation of behaviour and emotion (operationalized, for example, by personality constructs such as impulsivity) has been found to increase risk of heavy drinking in adolescence, as well as the experience of alcohol-related problems (Simons et al. 2005; Simons et al. 2004; Colder and Chassin 1999). Both negative affect and affect regulation are thought to involve distinct but overlapping neural circuits (Whittle et al. 2006), many of which are also critically involved in the neurobiological processes that characterise addiction (Goldstein and Volkow 2002; Koob 2006; Lubman et al. 2004; Volkow et al. 2012). Specifically, negative affect is believed to have a basis in limbic regions, in particular the amygdala and hippocampus (Whittle et al. 2006; Aggleton and Young 2000). Larger hippocampal and amygdala volumes have been associated with risk for disorders characterised by high levels of negative affect, with these regions decreasing in size with duration of illness (Whittle et al. 2006; Frodl et al. 2003). By contrast, affect regulation is thought to involve the top–down regulation of limbic regions by structures implicated in inhibition and executive control, including the dorsal region of the ACC and the orbitofrontal cortex (OFC; Whittle et al. 2006; Etkin et al. 2011; Shackman et al. 2011; Kringelbach and Rolls 2004). Smaller volumes or damage to these regions is associated with poor control over cognitive and affective processes, as well as impulsive, disinhibited, and socially inappropriate behaviours (Asami et al. 2008; Vasic et al. 2008; Giuliani et al. 2011; Kringelbach and Rolls 2004). As noted above, the offspring of alcoholics have been found to show structural
Psychopharmacology
or functional abnormalities in these regions when compared with healthy controls. Moreover, a number of studies have provided evidence that these abnormalities are related to the processing of negative affective stimuli and the ability to regulate affective responses and affect-driven behaviours (e.g., Acheson et al. 2009; Glahn et al. 2007; Heitzeg et al. 2008). Although the aim of the current study was to test the independent contributions of brain structure and temperament, these findings provide preliminary evidence that abnormalities in the brain regions that underpin affective processes may form a pathway to the emergence of later alcohol abuse and dependence in vulnerable individuals (Tessner and Hill 2010). We used a longitudinal design to examine whether differences in brain volume and affective temperament (measured at age 12) could predict the subsequent emergence of alcohol-related problems (measured at age 16). As multiple studies have provided evidence that smaller frontal volumes are associated with risk for alcoholism (Benegal et al. 2006; Hill et al. 2009), it was expected that risk for alcohol-related problems would be associated with smaller volumes of the ACC and OFC. By contrast, it was expected that risk would be associated with larger volumes of the amygdala and hippocampus, as although both larger (Hanson et al. 2010) and smaller (Hill et al. 2001; Benegal et al. 2006; Sjoerds et al. 2013) volumes of subcortical structures have been reported in high-risk offspring, there is evidence that risk for disorders characterized by high NA are associated with an increase in volume of these regions. In accordance with past research, we expected that high levels of negative affectivity and low affect regulation would also increase the risk of later problems.
sample (n=245) that over-represented adolescents with scores in the tails but retained the range in temperament seen in the larger screening sample (temperament scores in the selected sample remained normally distributed). At the baseline assessment, 155 of these adolescents underwent structural magnetic resonance imaging and were again administered the EATQ-R. At the follow-up assessment, which took place approximately 4 years (3.8±0.5) after the baseline assessment, 121 of these participants completed a questionnaire measuring substance use. There were no differences between participants who completed the follow-up assessments and participants who did not on measures of affective temperament (all p values>.39) or brain volume (all p values>.17). As the aim of this study was to examine risk factors for alcohol-related problems amongst adolescent drinkers, nondrinkers were excluded, leaving a total of 98 participants. Psychopathology was assessed using the Schedule for Affective Disorder and Schizophrenia for School-Aged Children: Epidemiologic Version (K-SADS-E [Orvaschel and Puig-Antich 1994]) at the baseline and follow-up assessments. Thirty-eight participants met criteria for one or more lifetime psychiatric disorders (see Table 1 for detail on specific psychopathology at each time point). Informed consent was obtained in accordance with the guidelines of the Human Research and Ethics Committee of the University of Melbourne.
Measures MRI image acquisition and morphometric analysis
Methods and materials Participants The sample consisted of 51 females and 47 males (mean age at baseline, 12.7 (SD±0.5 years; range, 11.8–13.6); mean age at follow-up, 16.5 (SD ± 0.5 years; range, 15.4–17.6). Participants were recruited from schools across metropolitan Melbourne, Australia, as part of a larger study on adolescent development (see Yap et al. 2010). The selection procedure for the larger study involved administering the Early Adolescent Temperament Questionnaire-Revised (Ellis and Rothbart 2001) to participants during class time, for the purpose of selecting a smaller sample that represented a broad spectrum of risk for later onset of psychopathology. Specifically, we recruited equal numbers of male and female participants who had scores that were 0–1, 1–2, 2–2.5, and greater than 2.5 standard deviations above and below the mean for the EATQ-R temperament dimensions of negative affectivity and effortful control. This resulted in a smaller
Magnetic resonance imaging scans were acquired using a 3-T scanner at the Brain Research Institute, Melbourne, Australia. A gradient echo volumetric acquisition sequence was used to obtain 124 T1-weighted contiguous 1.5-mm thick slices. Imaging parameters were as follows: repetition time=36 ms; echo time=9 ms; flip angle=35°, field of view=20 cm2, pixel matrix=410×410; and voxel dimensions=0.4883×0.4883× 1.5 mm). All regions of interest were defined and quantified based on techniques developed and validated by the Melbourne Neuropsychiatry Centre and manually traced using ANALYZE software (Mayo Clinic, Rochester, NY; http:// www.mayo.edu/bir/). An automated segmentation tool (FSL) was used to segment grey matter, white matter, and cerebrospinal fluid (Zhang et al. 2001). An estimate of whole brain volume (WBV) was obtained by summing grey and white matter pixel counts (i.e., cerebral grey and white matter, the cerebellum, and the brainstem). Within the defined ROIs, amygdala and hippocampal estimates were based on total voxels, whereas ACC and OFC estimates were based on grey
Psychopharmacology Table 1 Specific psychopathology at baseline and follow-up assessments
Psychopathology (n=38)
Baseline assessment
Follow-up assessment
Past disorder
Past disorder
Major depressive disorder (MDD) Depressive disorder NOS Post-traumatic stress disorder (PTSD) Social phobia Specific phobia Obsessive–compulsive disorder (OCD)
NOS depressive disorder not otherwise specified, ADHD attention-deficit hyperactivity disorder c
Had not used any substance (tobacco, alcohol, cannabis, or other illicit drug) at baseline assessment
Separation anxiety Adjustment disorder with depressed mood Oppositional-defiant disorder (ODD) Conduct disorder (CD) ADHD Attention-deficit disorder (ADD) Substance use disorderc Alcohol use disorderc
matter pixel counts. Intra- and inter-rater reliabilities (the latter with a second trained rater) were calculated for each raw ROI volume on a separate set of ten images. Intraclass correlation coefficients (most >0.9 and none
ORIGINAL INVESTIGATION
Volumetric differences in the anterior cingulate cortex prospectively predict alcohol-related problems in adolescence Ali Cheetham & Nicholas B. Allen & Sarah Whittle & Julian Simmons & Murat Yücel & Dan I. Lubman
Received: 11 June 2013 / Accepted: 3 February 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Rationale Individual differences in brain structure and function are suggested to exist prior to the onset of alcohol abuse. Cross-sectional studies have demonstrated abnormalities in brain regions underlying affective processes that may form a pathway to the emergence of later alcohol abuse and dependence in vulnerable individuals. However, no prospective studies have examined whether these abnormalities predict later problems with alcohol. Objective This study aims to examine whether individual differences in affect and brain volume prospectively predict alcohol-related problems in adolescence. Method Adolescent drinkers (n=98) were recruited from an ongoing prospective, longitudinal study examining adolescent emotional development. At age 12, participants underwent structural magnetic resonance imaging to obtain volumetric data on the amygdala, hippocampus, orbitofrontal cortex, and A. Cheetham : N. B. Allen : S. Whittle : J. Simmons Orygen Youth Health Research Centre, Centre for Youth Mental Health, The University of Melbourne, Melbourne, VIC, Australia A. Cheetham : D. I. Lubman (*) Turning Point Alcohol and Drug Centre, Eastern Health and Monash University, Melbourne, VIC, Australia e-mail: [email protected] N. B. Allen : J. Simmons Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, VIC, Australia S. Whittle : M. Yücel Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Melbourne, VIC, Australia M. Yücel Monash Clinical and Imaging Neuroscience, School of Psychology and Psychiatry, Monash University, Melbourne, VIC, Australia
anterior cingulate cortex (ACC), and completed a self-report measure of affective temperament. At age 16, participants completed a questionnaire measuring alcohol use, with 39 % reporting alcohol-related problems in the past year. Results Pre-existing differences in the left ACC predicted problem drinking. Alcohol-related problems were associated with higher levels of temperamental negative affectivity; however, these were not correlated with anterior cingulate volumes. Conclusions These findings indicate that individual differences in the structural morphology of the anterior cingulate, a region implicated in affective processes, self-control, and drug addiction, predict later alcohol-related problems. Although this finding remained significant after controlling for other substance use and psychopathology, future research is required to test its specificity for alcohol use disorders. Keywords Alcohol . Adolescence . Structural MRI . Anterior cingulate . Affect
Introduction Alcohol abuse makes a substantial contribution to preventable mortality and morbidity worldwide, particularly amongst adolescents and young adults (Ezzati et al. 2002; Rehm et al. 2009). The adolescent brain is thought to be particularly vulnerable to the effects of alcohol, due to ongoing processes of brain maturation that involve substantial remodelling of regions involved in affective, cognitive, and behavioural regulation (Crews et al. 2007; Lubman et al. 2007a; Nixon and McClain 2010). Accordingly, there is growing evidence that alcohol abuse and dependence during adolescence are associated with structural brain abnormalities, particularly in prefrontal and temporal regions (see Bava and Tapert 2010, for a review). However, while these
Psychopharmacology
regions may be sensitive to the effects of alcohol during adolescence, it is also possible that deficits or developmental delays in the maturation of some structures influence risk for problematic alcohol use during this period. As such, it is not clear whether abnormalities observed in studies of adolescents with alcohol use disorders reflect neurotoxicity associated with heavy alcohol use or premorbid vulnerability factors that increase risk for such disorders. Few studies have prospectively examined the neuroanatomical predictors of problematic alcohol use. Amongst adolescents with minimal use, altered activation in regions involved in response inhibition and working memory have been found to predict the initiation of heavy drinking (Wetherill et al. 2013; Norman et al. 2011; Squeglia et al. 2012). In addition, a recent study by Jacobus et al. (2013) found differences in white matter integrity between adolescents who went on to initiate heavy alcohol use and adolescents who went on to initiate both heavy alcohol and cannabis use, although no comparisons were made with nonsubstance-using controls. To our knowledge, no other studies have prospectively examined whether structural differences exist before the onset of heavy alcohol use. However, cross-sectional research examining the offspring of alcoholics has provided evidence that some abnormalities in brain structure and function may exist prior to the onset of alcohol abuse or dependence. Relative to healthy controls, individuals considered to be at high genetic risk for alcoholism have been found to demonstrate smaller volumes of the frontal cortex (Benegal et al. 2006; Hill et al. 2009) and amygdala (Hill et al. 2001; Benegal et al. 2006), both smaller (Benegal et al. 2006; Sjoerds et al. 2013) and larger (Hanson et al. 2010) volumes of the hippocampus and parahippocampal gyri, as well as altered white matter microstructure in tracts connecting prefrontal to cortical, striatal, and cerebellar regions (Herting et al. 2011; Herting et al. 2010). In addition, functional imaging studies have found altered activity in regions implicated in reward processing and cognitive control, including the amygdala (Glahn et al. 2007; Heitzeg et al. 2008), anterior cingulate cortex (ACC), and medial prefrontal regions (Acheson et al. 2009; Spadoni et al. 2008; Silveri et al. 2011; Kareken et al. 2010; Hill et al. 2007; Heitzeg et al. 2008; Heitzeg et al. 2010). While this field is still in its infancy, these studies provide evidence that individuals at risk for alcoholism demonstrate abnormalities in brain structure and function in the absence of any clinically significant problems with alcohol. The current study aimed to add to this literature by examining whether individual differences in brain volume could prospectively predict the experience of alcohol-related problems in a sample of healthy adolescents. In addition, we examined the influence of affective temperament on alcohol-
related problems in the same sample. There is considerable evidence that individual differences in affective functioning (i.e., the processes by which emotions are generated, maintained, and managed) are associated with the abuse of alcohol and other substances, regardless of whether a positive family history of alcoholism is present (Cheetham et al. 2010). In particular, negative affect (NA) has been frequently linked to indices of problematic alcohol use in adolescence and young adulthood. This includes evidence supporting a relationship between high trait negative affectivity and alcohol-related problems in community samples (e.g., Stewart et al. 2001), as well as the co-occurrence of alcohol use disorders with affective psychopathology (i.e., mood and anxiety disorders; Kushner et al. 2000; Page and Andrews 1996; Schuckit et al. 1997). Indeed, while drinking in response to negative affect does not appear to be a consistent predictor of alcohol use itself, it is frequently associated with alcohol-related problems during adolescence (e.g., Merrill and Read 2010; Simons et al. 2005; Kassel et al. 2000; Gaher et al. 2006). Affect regulation, which can refer to both the regulation of internal affective states as well as the control of overt behaviours driven by affective processes (Eisenberg et al. 2000), is also likely to be associated with problematic alcohol use during this period. Poor regulation of behaviour and emotion (operationalized, for example, by personality constructs such as impulsivity) has been found to increase risk of heavy drinking in adolescence, as well as the experience of alcohol-related problems (Simons et al. 2005; Simons et al. 2004; Colder and Chassin 1999). Both negative affect and affect regulation are thought to involve distinct but overlapping neural circuits (Whittle et al. 2006), many of which are also critically involved in the neurobiological processes that characterise addiction (Goldstein and Volkow 2002; Koob 2006; Lubman et al. 2004; Volkow et al. 2012). Specifically, negative affect is believed to have a basis in limbic regions, in particular the amygdala and hippocampus (Whittle et al. 2006; Aggleton and Young 2000). Larger hippocampal and amygdala volumes have been associated with risk for disorders characterised by high levels of negative affect, with these regions decreasing in size with duration of illness (Whittle et al. 2006; Frodl et al. 2003). By contrast, affect regulation is thought to involve the top–down regulation of limbic regions by structures implicated in inhibition and executive control, including the dorsal region of the ACC and the orbitofrontal cortex (OFC; Whittle et al. 2006; Etkin et al. 2011; Shackman et al. 2011; Kringelbach and Rolls 2004). Smaller volumes or damage to these regions is associated with poor control over cognitive and affective processes, as well as impulsive, disinhibited, and socially inappropriate behaviours (Asami et al. 2008; Vasic et al. 2008; Giuliani et al. 2011; Kringelbach and Rolls 2004). As noted above, the offspring of alcoholics have been found to show structural
Psychopharmacology
or functional abnormalities in these regions when compared with healthy controls. Moreover, a number of studies have provided evidence that these abnormalities are related to the processing of negative affective stimuli and the ability to regulate affective responses and affect-driven behaviours (e.g., Acheson et al. 2009; Glahn et al. 2007; Heitzeg et al. 2008). Although the aim of the current study was to test the independent contributions of brain structure and temperament, these findings provide preliminary evidence that abnormalities in the brain regions that underpin affective processes may form a pathway to the emergence of later alcohol abuse and dependence in vulnerable individuals (Tessner and Hill 2010). We used a longitudinal design to examine whether differences in brain volume and affective temperament (measured at age 12) could predict the subsequent emergence of alcohol-related problems (measured at age 16). As multiple studies have provided evidence that smaller frontal volumes are associated with risk for alcoholism (Benegal et al. 2006; Hill et al. 2009), it was expected that risk for alcohol-related problems would be associated with smaller volumes of the ACC and OFC. By contrast, it was expected that risk would be associated with larger volumes of the amygdala and hippocampus, as although both larger (Hanson et al. 2010) and smaller (Hill et al. 2001; Benegal et al. 2006; Sjoerds et al. 2013) volumes of subcortical structures have been reported in high-risk offspring, there is evidence that risk for disorders characterized by high NA are associated with an increase in volume of these regions. In accordance with past research, we expected that high levels of negative affectivity and low affect regulation would also increase the risk of later problems.
sample (n=245) that over-represented adolescents with scores in the tails but retained the range in temperament seen in the larger screening sample (temperament scores in the selected sample remained normally distributed). At the baseline assessment, 155 of these adolescents underwent structural magnetic resonance imaging and were again administered the EATQ-R. At the follow-up assessment, which took place approximately 4 years (3.8±0.5) after the baseline assessment, 121 of these participants completed a questionnaire measuring substance use. There were no differences between participants who completed the follow-up assessments and participants who did not on measures of affective temperament (all p values>.39) or brain volume (all p values>.17). As the aim of this study was to examine risk factors for alcohol-related problems amongst adolescent drinkers, nondrinkers were excluded, leaving a total of 98 participants. Psychopathology was assessed using the Schedule for Affective Disorder and Schizophrenia for School-Aged Children: Epidemiologic Version (K-SADS-E [Orvaschel and Puig-Antich 1994]) at the baseline and follow-up assessments. Thirty-eight participants met criteria for one or more lifetime psychiatric disorders (see Table 1 for detail on specific psychopathology at each time point). Informed consent was obtained in accordance with the guidelines of the Human Research and Ethics Committee of the University of Melbourne.
Measures MRI image acquisition and morphometric analysis
Methods and materials Participants The sample consisted of 51 females and 47 males (mean age at baseline, 12.7 (SD±0.5 years; range, 11.8–13.6); mean age at follow-up, 16.5 (SD ± 0.5 years; range, 15.4–17.6). Participants were recruited from schools across metropolitan Melbourne, Australia, as part of a larger study on adolescent development (see Yap et al. 2010). The selection procedure for the larger study involved administering the Early Adolescent Temperament Questionnaire-Revised (Ellis and Rothbart 2001) to participants during class time, for the purpose of selecting a smaller sample that represented a broad spectrum of risk for later onset of psychopathology. Specifically, we recruited equal numbers of male and female participants who had scores that were 0–1, 1–2, 2–2.5, and greater than 2.5 standard deviations above and below the mean for the EATQ-R temperament dimensions of negative affectivity and effortful control. This resulted in a smaller
Magnetic resonance imaging scans were acquired using a 3-T scanner at the Brain Research Institute, Melbourne, Australia. A gradient echo volumetric acquisition sequence was used to obtain 124 T1-weighted contiguous 1.5-mm thick slices. Imaging parameters were as follows: repetition time=36 ms; echo time=9 ms; flip angle=35°, field of view=20 cm2, pixel matrix=410×410; and voxel dimensions=0.4883×0.4883× 1.5 mm). All regions of interest were defined and quantified based on techniques developed and validated by the Melbourne Neuropsychiatry Centre and manually traced using ANALYZE software (Mayo Clinic, Rochester, NY; http:// www.mayo.edu/bir/). An automated segmentation tool (FSL) was used to segment grey matter, white matter, and cerebrospinal fluid (Zhang et al. 2001). An estimate of whole brain volume (WBV) was obtained by summing grey and white matter pixel counts (i.e., cerebral grey and white matter, the cerebellum, and the brainstem). Within the defined ROIs, amygdala and hippocampal estimates were based on total voxels, whereas ACC and OFC estimates were based on grey
Psychopharmacology Table 1 Specific psychopathology at baseline and follow-up assessments
Psychopathology (n=38)
Baseline assessment
Follow-up assessment
Past disorder
Past disorder
Major depressive disorder (MDD) Depressive disorder NOS Post-traumatic stress disorder (PTSD) Social phobia Specific phobia Obsessive–compulsive disorder (OCD)
NOS depressive disorder not otherwise specified, ADHD attention-deficit hyperactivity disorder c
Had not used any substance (tobacco, alcohol, cannabis, or other illicit drug) at baseline assessment
Separation anxiety Adjustment disorder with depressed mood Oppositional-defiant disorder (ODD) Conduct disorder (CD) ADHD Attention-deficit disorder (ADD) Substance use disorderc Alcohol use disorderc
matter pixel counts. Intra- and inter-rater reliabilities (the latter with a second trained rater) were calculated for each raw ROI volume on a separate set of ten images. Intraclass correlation coefficients (most >0.9 and none
