Factors associated with burnout and stress: multivariate linear regression analysis (n = 704).

<p>β: standardised regression coefficient.</p><p>VIF: variance inflation factor.</p>a<p>Coded as: 0 =  Male; 1 =  Female.</p>b<p>Coded as: 1 =  Professor or Associate Professor; 2 =  Assistant Professor; 3 =  Psychiatric Resident; 4 =  Postgraduate Student.</p>c<p>Coded as: 0 =  Married; 1 =  Not married.</p>d<p>Coded as: 0 =  Have children; 1 =  Do not have children.</p>e<p>Coded as: 1 =  Less than 40 hours; 2 = 40 to less than 50 hours; 3 = 50 hours or more.</p>f<p>Coded as: 1 =  None; 2 =  Less than 4 times; 3 = 5 to 9 times; 4 = 10 times or more.</p>g<p>Possible range: 1–5. Higher scores indicate higher satisfaction levels.</p>*<p>Statistically significant variables.</p

Means MBI scores and burnout rates.

<p>a Chi-squared test; the results of three burnout subsets were compared.</p

Rates of work-life balance and environmental satisfaction.

<p>A: Are you experiencing difficulties in maintaining your work-life balance? (1: not at all, 5: very much) B: Are you satisfied with your work environment? (1: not satisfied at all, 5: very much satisfied).</p

Association between work-life balance satisfaction and burnout.

<p>Are you experiencing difficulties in maintaining your work-life balance? (1: not at all, 5: very much).</p

Baseline characteristics of psychiatrists in the sample group.

<p>a Percentage of the total number of valid values for each variable.</p

Circuitry elements in the effect of the Val/Val genotype on dopamine levels.

<p>Relative to the Val/Met genotype, the COMT enzyme from the Val/Val genotype leads to reduced dopamine levels in the cortex, including the PFC and PCC. Although projections from the PFC to the midbrain directly contact dopaminergic cell groups in the ventral tegmental area that project back to the PFC to generate low dopamine levels, they indirectly elevate the dopamine levels via dopaminergic cell groups in the substantia nigra that project to the striatum [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142862#pone.0142862.ref029" target="_blank">29</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142862#pone.0142862.ref030" target="_blank">30</a>]. In the striatum, the direct influence of COMT is weak because the dopamine level is predominantly regulated by dopamine reuptake through presynaptic transporters [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142862#pone.0142862.ref031" target="_blank">31</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142862#pone.0142862.ref032" target="_blank">32</a>]. Therefore, Val/Val individuals have lower dopamine levels in the PCC and higher dopamine levels in the caudate than those in Val/Met individuals. DA = dopamine, PFC = prefrontal cortex, PCC = posterior cingulate cortex, VTA = ventral tegmental area, and SN = substantia nigra.</p

Clusters of significantly decreased gray matter volume in Val/Val individuals compared with that in Val/Met individuals.

<p>The SPM {t} is displayed onto the Diffeomorphic Anatomical Registration through Exponentiated Lie Algebra (DARTEL) template of gray matter. The volumes of the bilateral caudate and posterior cingulate cortex (PCC) were significantly smaller in Val/Val individuals than in Val/Met individuals (yellow areas). A-C: The sagittal, axial, and coronal images of the PCC. D: The sagittal image of the right caudate. E-F: The axial and corneal images of the bilateral caudate. G: The sagittal image of the left caudate. H: The color bar indicates the T-value.</p

Demographic Characteristics of Participants.

<p>Demographic Characteristics of Participants.</p

Results of Voxel-based morphometry analysis.

<p>Val = Valine; Met = Methionine; MDD = Major depression disorders; HS = healthy subjects; COMT = Catechol-O-methyltransferase, FDR = false discovery rate, MNI = Montreal Neurological Institute</p><p>Results of Voxel-based morphometry analysis.</p

Background of smokers and non-smokers.

<p>Abbreviation. AUDIT: Alcohol Use Disorders Identification Test; TDS: Tobacco Dependence Screener Scale; FTND: Fagerström Test for Nicotine Dependence; CO; carbon monoxide.</p><p>*Detailed information about the smoking-related clinical variables and the AUDIT scores of three subjects (N = 16) were not available. The mean AUDIT scores of the smokers (N = 16) was significantly higher than that of the nonsmokers (N = 18; smokers: 9.1±6.3; nonsmokers: 4.9±4.4; p = 0.022).</p