Externally oriented thinking style increases primary health care use in adolescence.

BACKGROUND: Alexithymia has been related to adult health care use. We investigated the association between alexithymia and the utilization of primary health care services by adolescents and young adults. METHODS: The participants (n = 751, aged 13-18 years) in this 5-year follow-up study were assessed with the 20-item Toronto Alexithymia Scale (TAS-20) and its three subscales, difficulty identifying feelings (DIF), difficulty describing feelings (DDF) and externally oriented thinking (EOT), and the 21-item Beck Depression Inventory (BDI). Primary health care data were gathered from health care centre registers in 2005-10. Generalized linear models and mediation analyses were used. RESULTS: An increase in the TAS-20 total score correlated with a higher number of primary health care and emergency care visits, but in multivariate general linear models, TAS-20 total scores were no longer significant. Younger age, female gender and an increase in the baseline EOT score are associated with a higher number of both primary health care and emergency room visits. In females, a smaller change in the EOT score from baseline to follow-up was associated with a higher number of primary health care visits. In mediation analyses, EOT had a direct effect on a higher number of primary health care and emergency room visits, whereas the BDI score mediated the incremental effect of DIF and DDF on visit numbers. CONCLUSIONS: The results suggest that an EOT style independently increases health care use by adolescents, whereas the effects of difficulties identifying and describing feelings on health care use are mediated by symptoms of depression.

Association of the N100 TMS-evoked potential with attentional processes: A motor cortex TMS-EEG study.

The most thoroughly studied transcranial magnetic stimulation (TMS)-evoked electroencephalogram (EEG) potential (TEP), N100, is often defined as a measure of cortical inhibition. We explored the association of the N100 amplitude with attention in 51 young healthy adults. Navigated TMS with simultaneous EEG registering was applied over the left primary motor cortex at the intensity of 110% of the resting motor threshold. Attention was assessed with the Paced Auditory Serial Addition Test (PASAT). We found a negative Pearson correlation (p = .023, r = -0.317) between the left centroparietal N100 amplitude and the PASAT score. Of the participants, the 17 with the highest PASAT scores and 17 with the lowes scores were selected for further analysis, in which a significant between-group difference in the left centroparietal N100 was found (p = .017). The topographic specificity of this finding was further confirmed with linear mixed model (LMM) analysis, in which significant differences were detected in the N100 amplitude; most prominently in the left centroparietal region (p = .001). A smaller N100 amplitude was associated with better performance in the attention task. Our findings suggest that the GABA-B-ergic TEP N100 is associated with attentional processes and thus represents cortical inhibition beyond motor inhibition.

Heavy alcohol use in adolescence is associated with altered cortical activity: a combined TMS-EEG study.

Long-term alcohol use affects cognitive and neurophysiological functioning as well as structural brain development. Combining simultaneous electroencephalogram (EEG) recording with transcranial magnetic stimulation (TMS) enables direct, in vivo exploration of cortical excitability and assessment of effective and functional connectivity. In the central nervous system, the effects of alcohol are particularly mediated by alterations in gamma-aminobutyric acid (GABA)ergic neurotransmission, and TMS-evoked potentials (TEPs) N45 and N100 in EEG are known to reflect GABAergic function. However, no previous studies have examined the effects of long-term alcohol use in adolescence on TEPs. In this study, a total of 27 young adults with heavy alcohol use in adolescence and 25 age-matched, gender-matched and education-matched controls with little or no alcohol use participated in TMS-EEG measurements. The motor cortex (M1) was stimulated with an intensity of 90 percent of the resting motor threshold of the abductor pollicis brevis muscle. No significant differences were found in the resting motor threshold, TEP latencies or neuropsychological functioning between the groups. We observed an increase in the global mean field power in the time window of 54- to 75-millisecond post-TMS, as well as significant topographical differences in the P60 and N100 in those with a history of heavy drinking. Furthermore, there was a marked increase in the GABAergic N45 amplitude in alcohol users. These findings suggest that long-term alcohol use in adolescence, even when not meeting the diagnostic criteria for a disorder, is associated with changes in connectivity and cortical excitability.

Cortical thickness is inversely associated with transcranial magnetic stimulation-evoked N45 potential among young adults whose heavy drinking began in adolescence.

BACKGROUND: Adolescence is a particularly vulnerable stage of development in terms of the deleterious effects of alcohol. Both lower gray matter (GM) volume and greater GABAergic activity have been associated with chronic alcohol consumption during adolescence. However, the association between these measures has not been investigated. METHODS: In this exploratory study, we compared 26 young adults with a 10year history of heavy alcohol consumption with 21 controls who used little or no alcohol. Simultaneous transcranial magnetic stimulation and electroencephalography were used to assess transcranial magnetic stimulation-evoked N45 potentials, reflecting a balance between GABAergic inhibition and N-methyl-D-aspartate (NMDA) receptor-mediated glutaminergic excitation in the brain. GM thickness was measured from magnetic resonance images and GM and N45 potentials were then correlated. RESULTS: Cortical thickness was significantly lower in several brain regions in the heavy-drinking group than the light-drinking group. The N45 amplitude was significantly larger frontally in the heavy-drinking group. Among heavy drinkers, there were several statistically significant correlations between thinner GM and larger frontal N45 amplitudes that were not detectable in the light-drinking group. The strongest correlations were detected in the frontal and parietal lobes, especially in the left superior frontal gyrus and the left supramarginal gyrus, and in both hemispheres in the superior parietal lobes. CONCLUSIONS: These findings show that a thinner cortex and greater inhibitory neurotransmission are correlated in certain brain regions among young, long-term heavy alcohol users. Studies are needed to explore the possible causal mechanisms underlying these effects.

Stability of alexithymia is low from adolescence to young adulthood, and the consistency of alexithymia is associated with symptoms of depression and dissociation.

BACKGROUND: The aims of this study were to investigate the stability of alexithymia from adolescence to young adulthood, as well as the association between alexithymia, peer relationships, and symptoms of depression and dissociation. METHODS: The participants (n = 755, aged 13-18 years) were assessed with self-rated questionnaires and the 20-item Toronto Alexithymia Scale (TAS-20) at baseline in 2005 and on follow-up in 2011. RESULTS: The changes in the TAS-20 total score (t = -12.26) and the scores for its subscales, difficulty identifying feelings (DIF) (t = -4.04), difficulty describing feelings (DDF) (t = -5.10), and externally oriented thinking (EOT) (t = -18.23), were statistically significant (p < 0.001). Effect sizes (Cohen's d) for the change indicating absolute stability were small for DIF (-0.15) and DDF (-0.19), medium for TAS-20 total (-0.45), and large for EOT (-0.66) scores. Moderate correlations in test-retests with Spearman's ρ (TAS-20 total 0.46, DIF 0.41, DDF 0.39, EOT 0.43) indicated relative stability, whereas low intraclass correlation coefficients (ICCs) (respectively 0.41, 0.39, 0.37, 0.37) indicated poor reliability of test-retests. In regression analyses, poor relationships with peers, loneliness, and symptoms of depression and dissociation at baseline associated with alexithymia at baseline and on follow-up. Unlike EOT, increases in the TAS-20 total, DIF, and DDF scores during the 6-year follow-up associated with baseline symptoms of depression and dissociation. CONCLUSIONS: Alexithymia in adolescence is not always a reliable predictor of alexithymia in young adulthood. Mental health symptoms appear to affect the consistency of alexithymia during adolescent development.

Heavy drinking from adolescence to young adulthood is associated with an altered cerebellum.

Excessive alcohol use results in cerebellar damage in adults, but there has been less research on how alcohol use during adolescence affects the cerebellum. In this study, we observed that heavy drinking from adolescence to young adulthood was associated with altered volumes of cerebellar lobules. The study included two groups consisting of 33 heavy-drinking and 25 light-drinking participants. The heavy-drinking participants were highly functional young adults without alcohol use disorder, but with a history of regular heavy alcohol consumption. The participants were 13-18 years old at baseline and were followed for 10 years. At the age of 21-28 years, the participants underwent magnetic resonance imaging (MRI). From the MR images, the cerebellum was segmented into 12 lobules using the CERES pipeline. Heavy drinking did not influence the absolute cerebellar volume, but changes were observed in posterior cerebellar lobules associated with motor and cognitive functions. The absolute volume (p = 0.038) and gray matter volume (p = 0.034) of Crus II (hemispheres combined) were smaller in the heavy-drinking group. Furthermore, the relative volume of the right VIIIB lobule was larger in the HD group (p = 0.036). However, there were no differences in the absolute right VIIIB volumes (p = 0.198) between the groups. Our results suggest changes in the cerebellum in healthy young adults with a history of heavy drinking from adolescence. The exact implications and significance of these findings require further research.

Repeated Transcranial Magnetic Stimulation-Induced Motor Evoked Potentials Correlate With the Subject-Specific Serum Metabolic Profile of Creatine.

PURPOSE: Transcranial magnetic stimulation-induced motor responses have been considered to mainly reflect the electrophysiological characteristics of the central motor system. However, certain motor phenomena, such as the magnitude of repetition suppression measured with motor evoked potentials (MEPs), could also in part be influenced by metabolic processes in the peripheral muscles and in both the peripheral and central nervous system. Repetition suppression is an inhibitory phenomenon in which the amplitude of MEP decreases in comparison to that of the first MEP in a train of transcranial magnetic stimulation pulses. This study aimed to identify possible metabolic processes influencing repetition suppression. METHODS: The metabolic profiles from serum samples and repetition suppression from the right abductor pollicis brevis muscle were measured in 73 subjects (37 female subjects). Repetition suppression was measured using trains of transcranial magnetic stimulation stimuli consisting of 4 identical single pulses at 1-second intervals. The trains were repeated every 20 seconds, and 30 trains were given with a stimulation intensity of 120% of the resting motor threshold of the abductor pollicis brevis. Thus, a total of 120 stimuli were administered. RESULTS: The main finding was a significant negative relationship between serum creatine levels and the magnitude of repetition suppression (standardized ß coefficient (ß) = -0.43; P < 0.001). In other words, higher creatine levels corresponded to a smaller decrement in the MEP amplitude in response to repetition. When MEPs were not repeated, no relationship was observed (ß = 0.09; P = 0.454). Creatine is used to form phosphocreatine, which in turn is needed to resynthesize adenosine triphosphate from adenosine diphosphate in situations requiring high amounts of energy in muscles and neural cells. CONCLUSIONS: For the first time, this study demonstrated a connection between repeated MEPs and peripheral serum metabolites linked to muscle function. These findings could explain some of the intersubject variability commonly observed in MEPs when the pulses are repeated.

Effects of long-term adolescent alcohol consumption on white matter integrity and their correlations with metabolic alterations.

Alcohol-related white matter (WM) microstructural changes have not been fully elucidated in adolescents. We aimed to investigate influences of subclinical alcohol use during adolescence on WM microstructure and to characterize those with serum metabolic alterations. 35 moderate-to-heavy drinkers (15 males, 20 females) and 27 controls (12 males, 15 females) were selected based on their ten-year Alcohol Use Disorders Identification Test scores measured at three time points. Magnetic resonance imaging was conducted at endpoint time. Whole brain analysis of fractional anisotropy (FA) was performed. Diffusivity indices in the significant regions were computed for between-group comparisons and correlation analyses with serum metabolite concentrations. Decreased FA was found in moderate-to-heavy drinking men in anterior corpus callosum, superior/anterior corona radiata and right inferior fronto-occipital fasciculus, accompanied by increased radial diffusivity and a smaller area of reduced axial diffusivity, which correlated with serum metabolites playing roles in energy metabolism, myelination and axonal degeneration. No significant difference in FA was detected between female or mixed-gender moderate-to-heavy drinking subjects and controls, supporting gender differences in the relationship between adolescent alcohol use and neurodevelopmental trajectories. Future researches with longitudinal imaging data are warranted for comprehensive evaluation on potentially reversible effects of alcohol use over adolescent brain.

Changes in the serum metabolite profile correlate with decreased brain gray matter volume in moderate-to-heavy drinking young adults.

Our aim was to analyze metabolite profile changes in serum associated with moderate-to-heavy consumption of alcohol in young adults and to evaluate whether these changes are connected to reduced brain gray matter volumes. These study population consisted of young adults with a 10-year history of moderate-to-heavy alcohol consumption (n = 35) and light-drinking controls (n = 27). We used the targeted liquid chromatography mass spectrometry method to measure concentrations of metabolites in serum, and 3.0 T magnetic resonance imaging to assess brain gray matter volumes. Alterations in amino acid and energy metabolism were observed in the moderate-to-heavy drinking young adults when compared to the controls. After correction for multiple testing, the group of moderate-to-heavy drinking young adults had increased serum concentrations of 1-methylhistamine (p = 0.001, d = 0.82) when compared to the controls. Furthermore, concentrations of 1-methylhistamine (r = -0.48, p = 0.004) and creatine (r = -0.52, p = 0.001) were negatively correlated with the brain gray matter volumes in the females. Overall, our results show association between moderate-to-heavy use of alcohol and altered metabolite profile in young adults as well as suggesting that some of these changes could be associated with the reduced brain gray matter volume.