Proposing a communication module to enhance dental students' attitudes towards people with dementia: Phase 1 of a curriculum revision study.

INTRODUCTION: The number of mentally altered patients a dentist meets in practice is increasing and interaction with them can be very challenging. As a baseline for an interventional study, we want to assess the attitude of dental students and identify areas of improvement in patient communication. This work compares the attitude of dental students towards people suffering from dementia to the attitudes of trained medical caregivers and the general population. Our aim is to use the results to assess the need for training in communicating with mentally altered patients. MATERIALS AND METHODS: Fourth-year dental students attended two lectures on dementia given by a psychiatrist as part of the geriatric dentistry lecture and were questioned afterwards using the Dementia Attitude Scale. In 2016 and 2017, 73 students at the University of Greifswald were interviewed. The response rate was 84%. Using a factor analysis, the Dementia Attitude Scale's validated questions were interpreted and compared with data from nursing staff from Switzerland and the USA. RESULTS: The factor analysis of the data showed the same two-factor loadings as the comparative groups, and that dental students' attitude is more comparable to the general population than to medically trained nursing staff. CONCLUSION: Given the results, we conclude that the implementation of a communication module can serve in improving the attitude of dental students towards patients with dementia.

Interaction of childhood abuse and depressive symptoms on cortical thickness: a general population study.

Childhood abuse was inconsistently related to whole-brain cortical thickness in former studies. However, both childhood abuse and cortical thickness have been associated with depressive symptoms. We hypothesised that childhood abuse moderates the association between depressive symptoms and cortical thickness. In 1551 individuals of the general population, associations between whole-brain cortical thickness and the interaction of childhood abuse (emotional, physical, and sexual) and depressive symptoms were analysed using an ANCOVA. Linear regression analyses were used to estimate the same effect on the cortical thickness of 34 separate regions (Desikan-Killiany-atlas). A significant interaction effect of childhood abuse and depressive symptoms was observed for whole-brain cortical thickness (F(2, 1534) = 5.28, p = 0.007). A thinner cortex was associated with depressive symptoms in abused (t value = 2.78, p = 0.025) but not in non-abused participants (t value = - 1.50, p = 0.224). Focussing on non-depressed participants, a thicker whole-brain cortex was found in abused compared to non-abused participants (t value = - 2.79, p = 0.025). Similar interaction effects were observed in 12 out of 34 cortical regions. Our results suggest that childhood abuse is associated with reduced cortical thickness in subjects with depressive symptoms. In abused subjects without depressive symptoms, larger cortical thickness might act compensatory and thus reflect resilience against depressive symptoms.

Common genetic variants influence human subcortical brain structures.

The highly complex structure of the human brain is strongly shaped by genetic influences. Subcortical brain regions form circuits with cortical areas to coordinate movement, learning, memory and motivation, and altered circuits can lead to abnormal behaviour and disease. To investigate how common genetic variants affect the structure of these brain regions, here we conduct genome-wide association studies of the volumes of seven subcortical regions and the intracranial volume derived from magnetic resonance images of 30,717 individuals from 50 cohorts. We identify five novel genetic variants influencing the volumes of the putamen and caudate nucleus. We also find stronger evidence for three loci with previously established influences on hippocampal volume and intracranial volume. These variants show specific volumetric effects on brain structures rather than global effects across structures. The strongest effects were found for the putamen, where a novel intergenic locus with replicable influence on volume (rs945270; P = 1.08 × 10(-33); 0.52% variance explained) showed evidence of altering the expression of the KTN1 gene in both brain and blood tissue. Variants influencing putamen volume clustered near developmental genes that regulate apoptosis, axon guidance and vesicle transport. Identification of these genetic variants provides insight into the causes of variability in human brain development, and may help to determine mechanisms of neuropsychiatric dysfunction.

[Medical education in psychosocial disciplines in times of the COVID-19 pandemic - first experiences]. / Lehre in den psychosozialen medizinischen Fächern in Zeiten der COVID-19-Pandemie ­ erste Erfahrungen.

AIM: In specialties that heavily rely on communication skills such as psychiatry, psychotherapy and psychosomatic medicine, teaching in times of the COVID-19 pandemic is especially challenging. In this overview, educators and course directors report their experiences in eteaching and share their innovative solutions. METHODS: We present a collection of methods that relate to teaching and assessment as well as student activation. RESULTS: A range of helpful tools for teaching were compiled. This includes instructional videos with simulated patients, structured homework to document a mental status examination, structured hand-offs, and practical examinations in video format. Motivational techniques include podcasts with interviews with clinicians and patients and teaching with the use of cinematic material. DISCUSSION: Switching to online formats creates opportunities and advantages for the advancement of time- and location-independent learning. A fast conversion in this direction might also pose some disadvantages. A direct patient-student interaction is critical for engaging with transference, countertransference and situational aspects for teaching in psychosocial disciplines. Empirical studies of the effectiveness of these newly developed formats and faculty development for digital teaching are necessary.

Interactive impact of childhood maltreatment, depression, and age on cortical brain structure: mega-analytic findings from a large multi-site cohort.

BACKGROUND: Childhood maltreatment (CM) plays an important role in the development of major depressive disorder (MDD). The aim of this study was to examine whether CM severity and type are associated with MDD-related brain alterations, and how they interact with sex and age. METHODS: Within the ENIGMA-MDD network, severity and subtypes of CM using the Childhood Trauma Questionnaire were assessed and structural magnetic resonance imaging data from patients with MDD and healthy controls were analyzed in a mega-analysis comprising a total of 3872 participants aged between 13 and 89 years. Cortical thickness and surface area were extracted at each site using FreeSurfer. RESULTS: CM severity was associated with reduced cortical thickness in the banks of the superior temporal sulcus and supramarginal gyrus as well as with reduced surface area of the middle temporal lobe. Participants reporting both childhood neglect and abuse had a lower cortical thickness in the inferior parietal lobe, middle temporal lobe, and precuneus compared to participants not exposed to CM. In males only, regardless of diagnosis, CM severity was associated with higher cortical thickness of the rostral anterior cingulate cortex. Finally, a significant interaction between CM and age in predicting thickness was seen across several prefrontal, temporal, and temporo-parietal regions. CONCLUSIONS: Severity and type of CM may impact cortical thickness and surface area. Importantly, CM may influence age-dependent brain maturation, particularly in regions related to the default mode network, perception, and theory of mind.

Alexithymia Is Associated with Altered Cortical Thickness Networks in the General Population.

BACKGROUND: Alexithymia is a personality trait characterized by difficulties in identifying and describing emotions and associated with various psychiatric disorders. Neuroimaging studies found evidence for morphological and functional brain alterations in alexithymic subjects. However, the neurobiological mechanisms underlying alexithymia remain incompletely understood. METHODS: We study the association of alexithymia with cortical correlation networks in a large community-dwelling sample of the Study of Health in Pomerania. Our analysis includes data of n = 2,199 individuals (49.4% females, age = 52.1 ± 13.6 years) which were divided into a low and high alexithymic group by a median split of the Toronto Alexithymia Scale. Cortical correlation networks were constructed based on the mean thicknesses of 68 regions, and differences in centralities were investigated. RESULTS: We found a significantly increased centrality of the right paracentral lobule in the high alexithymia network after correction for multiple testing. Several other regions with motoric and sensory functions showed altered centrality on a nominally significant level. CONCLUSIONS: Finding increased centrality of the paracentral lobule, a brain area with sensory as well as motoric features and involvement in bowel and bladder voiding, may contribute to explain the association of alexithymia with functional somatic disorders and chronic pain syndromes.

Associations of trauma exposure and post-traumatic stress disorder with the activity of the renin-angiotensin-aldosterone-system in the general population.

BACKGROUND: Previous studies suggested that exposure to traumatic events during childhood and adulthood and post-traumatic stress disorder (PTSD) are associated with a dysregulation of different neuroendocrine systems. However, the activity of the renin-angiotensin-aldosterone-system (RAAS) in relation to trauma/PTSD has been largely neglected. METHODS: Traumatization, PTSD, and plasma concentrations of renin and aldosterone were measured in 3092 individuals from the general population. Subgroups according to the status of traumatization ('without trauma'; 'trauma, without PTSD', 'PTSD') were formed and compared regarding renin and aldosterone concentrations. Additionally, we calculated the associations between the number of traumata, renin, and aldosterone concentrations. Finally, associations of PTSD with renin/aldosterone levels were controlled for the number of traumata ('trauma load'). RESULTS: Levels of renin, but not aldosterone, were increased in traumatized persons without PTSD (p = 0.02) and, even stronger, with PTSD (p < 0.01). Moreover, we found a dose-response relation between the number of traumata and renin levels (ß = 0.065; p < 0.001). Regression analyses showed PTSD as a significant predictor of renin (ß = 0.38; p < 0.01). This effect was only slightly attenuated when controlled for trauma load (ß = 0.32; p < 0.01). CONCLUSIONS: Our results suggest that traumatization has lasting and cumulative effects on RAAS activity. Finding elevated renin levels in PTSD independent from trauma load supports the concept of PTSD as a disorder with specific neuroendocrine characteristics. Alternatively, elevated renin levels in traumatized persons may increase the risk for developing PTSD. Our findings contribute to explain the relationship between traumatic stress/PTSD and physical disorders.

Stigma as a barrier to recognizing personal mental illness and seeking help: a prospective study among untreated persons with mental illness.

It is unclear to what extent failure to recognize symptoms as potential sign of a mental illness is impeding service use, and how stigmatizing attitudes interfere with this process. In a prospective study, we followed a community sample of 188 currently untreated persons with mental illness (predominantly depression) over 6 months. We examined how lack of knowledge, prejudice and discrimination impacted on self-identification as having a mental illness, perceived need, intention to seek help, and help-seeking, both with respect to primary care (visiting a general practitioner, GP) and specialist care (seeing a mental health professional, MHP). 67% sought professional help within 6 months. Fully saturated path models accounting for baseline depressive symptoms, previous treatment experience, age and gender showed that self-identification predicted need (beta 0.32, p < 0.001), and need predicted intention (GP: beta 0.45, p < 0.001; MHP: beta 0.38, p < 0.001). Intention predicted service use with a MHP after 6 months (beta 0.31, p < 0.01; GP: beta 0.17, p = 0.093). More knowledge was associated with more self-identification (beta 0.21, p < 0.01), while support for discrimination was associated with lower self-identification (beta - 0.14, p < 0.05). Blaming persons with mental illness for their problem was associated with lower perceived need (beta - 0.16, p < 0.05). Our models explained 37% of the variance of seeking help with a MHP, and 33% of help-seeking with a GP. Recognizing one's own mental illness and perceiving a need for help are impaired by lack of knowledge, prejudice, and discrimination. Self-identification is a relevant first step when seeking help for mental disorders.

Association of Brain-Derived Neurotrophic Factor and Vitamin D with Depression and Obesity: A Population-Based Study.

BACKGROUND: Depression and obesity are widespread and closely linked. Brain-derived neurotrophic factor (BDNF) and vitamin D are both assumed to be associated with depression and obesity. Little is known about the interplay between vitamin D and BDNF. We explored the putative associations and interactions between serum BDNF and vitamin D levels with depressive symptoms and abdominal obesity in a large population-based cohort. METHODS: Data were obtained from the population-based Study of Health in Pomerania (SHIP)-Trend (n = 3,926). The associations of serum BDNF and vitamin D levels with depressive symptoms (measured using the Patient Health Questionnaire) were assessed with binary and multinomial logistic regression models. The associations of serum BDNF and vitamin D levels with obesity (measured by the waist-to-hip ratio [WHR]) were assessed with binary logistic and linear regression models with restricted cubic splines. RESULTS: Logistic regression models revealed inverse associations of vitamin D with depression (OR = 0.966; 95% CI 0.951-0.981) and obesity (OR = 0.976; 95% CI 0.967-0.985). No linear association of serum BDNF with depression or obesity was found. However, linear regression models revealed a U-shaped association of BDNF with WHR (p < 0.001). CONCLUSION: Vitamin D was inversely associated with depression and obesity. BDNF was associated with abdominal obesity, but not with depression. At the population level, our results support the relevant roles of vitamin D and BDNF in mental and physical health-related outcomes.

White matter hyperintensities and imaging patterns of brain ageing in the general population.

White matter hyperintensities are associated with increased risk of dementia and cognitive decline. The current study investigates the relationship between white matter hyperintensities burden and patterns of brain atrophy associated with brain ageing and Alzheimer's disease in a large populatison-based sample (n = 2367) encompassing a wide age range (20-90 years), from the Study of Health in Pomerania. We quantified white matter hyperintensities using automated segmentation and summarized atrophy patterns using machine learning methods resulting in two indices: the SPARE-BA index (capturing age-related brain atrophy), and the SPARE-AD index (previously developed to capture patterns of atrophy found in patients with Alzheimer's disease). A characteristic pattern of age-related accumulation of white matter hyperintensities in both periventricular and deep white matter areas was found. Individuals with high white matter hyperintensities burden showed significantly (P < 0.0001) lower SPARE-BA and higher SPARE-AD values compared to those with low white matter hyperintensities burden, indicating that the former had more patterns of atrophy in brain regions typically affected by ageing and Alzheimer's disease dementia. To investigate a possibly causal role of white matter hyperintensities, structural equation modelling was used to quantify the effect of Framingham cardiovascular disease risk score and white matter hyperintensities burden on SPARE-BA, revealing a statistically significant (P < 0.0001) causal relationship between them. Structural equation modelling showed that the age effect on SPARE-BA was mediated by white matter hyperintensities and cardiovascular risk score each explaining 10.4% and 21.6% of the variance, respectively. The direct age effect explained 70.2% of the SPARE-BA variance. Only white matter hyperintensities significantly mediated the age effect on SPARE-AD explaining 32.8% of the variance. The direct age effect explained 66.0% of the SPARE-AD variance. Multivariable regression showed significant relationship between white matter hyperintensities volume and hypertension (P = 0.001), diabetes mellitus (P = 0.023), smoking (P = 0.002) and education level (P = 0.003). The only significant association with cognitive tests was with the immediate recall of the California verbal and learning memory test. No significant association was present with the APOE genotype. These results support the hypothesis that white matter hyperintensities contribute to patterns of brain atrophy found in beyond-normal brain ageing in the general population. White matter hyperintensities also contribute to brain atrophy patterns in regions related to Alzheimer's disease dementia, in agreement with their known additive role to the likelihood of dementia. Preventive strategies reducing the odds to develop cardiovascular disease and white matter hyperintensities could decrease the incidence or delay the onset of dementia.

Sequence-based characterization of structural variation in the mouse genome.

Structural variation is widespread in mammalian genomes and is an important cause of disease, but just how abundant and important structural variants (SVs) are in shaping phenotypic variation remains unclear. Without knowing how many SVs there are, and how they arise, it is difficult to discover what they do. Combining experimental with automated analyses, we identified 711,920 SVs at 281,243 sites in the genomes of thirteen classical and four wild-derived inbred mouse strains. The majority of SVs are less than 1 kilobase in size and 98% are deletions or insertions. The breakpoints of 160,000 SVs were mapped to base pair resolution, allowing us to infer that insertion of retrotransposons causes more than half of SVs. Yet, despite their prevalence, SVs are less likely than other sequence variants to cause gene expression or quantitative phenotypic variation. We identified 24 SVs that disrupt coding exons, acting as rare variants of large effect on gene function. One-third of the genes so affected have immunological functions.

Mouse genomic variation and its effect on phenotypes and gene regulation.

We report genome sequences of 17 inbred strains of laboratory mice and identify almost ten times more variants than previously known. We use these genomes to explore the phylogenetic history of the laboratory mouse and to examine the functional consequences of allele-specific variation on transcript abundance, revealing that at least 12% of transcripts show a significant tissue-specific expression bias. By identifying candidate functional variants at 718 quantitative trait loci we show that the molecular nature of functional variants and their position relative to genes vary according to the effect size of the locus. These sequences provide a starting point for a new era in the functional analysis of a key model organism.

Effect of the interaction between childhood abuse and rs1360780 of the FKBP5 gene on gray matter volume in a general population sample.

OBJECTIVE: The FKBP5 gene codes for a co-chaperone that regulates glucocorticoid receptor sensitivity and thereby impacts the reactivity of the hypothalamic-pituitary-adrenal (HPA)-axis. Evidence suggested that subjects exposed to childhood abuse and carrying the TT genotype of the FKBP5 gene single nucleotide polymorphism (SNP) rs1360780 have an increased susceptibility to stress-related disorders. METHOD: The hypothesis that abused TT genotype carriers show changes in gray matter (GM) volumes in affect-processing brain areas was investigated. About 1,826 Caucasian subjects (age ≤ 65 years) from the general population [Study of Health in Pomerania (SHIP)] in Germany were investigated. The interaction between rs1360780 and child abuse (Childhood Trauma Questionnaire) and its effect on GM were analyzed. RESULTS: Voxel-based whole-brain interaction analysis revealed three large clusters (FWE-corrected) of reduced GM volumes comprising the bilateral insula, the superior and middle temporal gyrus, the bilateral hippocampus, the right amygdala, and the bilateral anterior cingulate cortex in abused TT carriers. These results were not confounded by major depressive disorders. In region of interest analyses, highly significant volume reductions in the right hippocampus/parahippocampus, the bilateral anterior and middle cingulate cortex, the insula, and the amygdala were confirmed in abused TT carriers compared with abused CT/CC carriers. CONCLUSION: The results supported the hypothesis that the FKBP5 rs1360780 TT genotype predisposes subjects who have experienced childhood abuse to widespread structural brain changes in the subcortical and cortical emotion-processing brain areas. Those brain changes might contribute to an increased vulnerability of stress-related disorders in TT genotype carriers.

From Childhood Trauma to Adult Dissociation: The Role of PTSD and Alexithymia.

BACKGROUND: The mechanism of how childhood trauma leads to increased risk for adult dissociation is not sufficiently understood. We sought to investigate the predicting effects and the putatively mediating roles of PTSD and alexithymia on the path from childhood trauma to adult dissociation. METHODS: A total of 666 day-clinic outpatients were administered the Childhood Trauma Questionnaire (CTQ), the Toronto Alexithymia Scale (TAS-20), the Posttraumatic Diagnostic Scale (PDS), and the Dissociative Experiences Scale (DES) and controlled for sex, age, and the Global Symptom Index (GSI). Linear regression analyses and mediation analyses were applied. RESULTS: Independent predictive effects on dissociation were found for childhood trauma, alexithymia and PDS, even after adjusting for GSI. Effects of childhood neglect on dissociation were slightly stronger than of abuse. Alexithymia did not mediate the path from childhood trauma to dissociation. Mediation by PDS was specific for childhood abuse, with all PTSD symptom clusters being significantly involved. CONCLUSIONS: Childhood abuse and neglect are important predictors of dissociation. While the effects of abuse are mediated by PTSD, the mechanism of how neglect leads to dissociation remains unclear. The results further support the predictive value of alexithymia for adult dissociation above and beyond the effects of childhood trauma, PTSD, and GSI scores.

Association between waist circumference and gray matter volume in 2344 individuals from two adult community-based samples.

We analyzed the putative association between abdominal obesity (measured in waist circumference) and gray matter volume (Study of Health in Pomerania: SHIP-2, N=758) adjusted for age and gender by applying volumetric analysis and voxel-based morphometry (VBM) with VBM8 to brain magnetic resonance (MR) imaging. We sought replication in a second, independent population sample (SHIP-TREND, N=1586). In a combined analysis (SHIP-2 and SHIP-TREND) we investigated the impact of hypertension, type II diabetes and blood lipids on the association between waist circumference and gray matter. Volumetric analysis revealed a significant inverse association between waist circumference and gray matter volume. VBM in SHIP-2 indicated distinct inverse associations in the following structures for both hemispheres: frontal lobe, temporal lobes, pre- and postcentral gyrus, supplementary motor area, supramarginal gyrus, insula, cingulate gyrus, caudate nucleus, olfactory sulcus, para-/hippocampus, gyrus rectus, amygdala, globus pallidus, putamen, cerebellum, fusiform and lingual gyrus, (pre-) cuneus and thalamus. These areas were replicated in SHIP-TREND. More than 76% of the voxels with significant gray matter volume reduction in SHIP-2 were also distinct in TREND. These brain areas are involved in cognition, attention to interoceptive signals as satiety or reward and control food intake. Due to our cross-sectional design we cannot clarify the causal direction of the association. However, previous studies described an association between subjects with higher waist circumference and future cognitive decline suggesting a progressive brain alteration in obese subjects. Pathomechanisms may involve chronic inflammation, increased oxidative stress or cellular autophagy associated with obesity.

Alexithymia and self-directedness as predictors of psychopathology and psychotherapeutic treatment outcome.

OBJECTIVE: Alexithymia, a common personality style of patients seeking psychotherapeutic help, is associated with illness severity and negative treatment outcome in various mental disorders. Still, it remains unclear how alexithymia influences psychopathology and the therapeutic processes. In previous studies, a strong association of alexithymia with self-directedness (SD), a dimension of Cloninger's Temperament and Character Inventory (TCI) has been shown. In this study, we investigated the interaction of alexithymia and SD, and their impact on general psychopathology and on treatment outcome. METHOD: 716 consecutively admitted day-clinic outpatients were examined at admission (t0) and discharge (t1). The Toronto Alexithymia Scale 20 (TAS-20), the SD subscale of the TCI and the Symptom Checklist 90 (SCL-90-R) were administered. Linear regression analyses were performed to calculate associations and the predictive power of TAS-20 and SD on psychopathology at admission and treatment outcome. ANOVA was used to calculate interactions of TAS-20 and SD on treatment outcome. A general linear model was applied to compare the outcome of four subgroups, defined by high/low TAS-20 and SD scores. RESULTS: Regression analyses revealed significant prediction of the baseline General Severity Index (GSIt0) by TAS-20 (df=4, 711; Beta: 0.385; p<0.001) and SD (Beta: -0.365; p<0.001). The whole model accounted for 41% of the explained variance. On subscale level, the 'Difficulties in identifying feelings' facet (DIF) of TAS-20 was the strongest predictor of GSIt0 (Beta: 0.478, P<0.001) and GSIt1 (Beta: 0.072, p=0.049). Therapeutic outcome measured by GSIt1 was significantly predicted by SD (df=5, 710; Beta: -0.065; p=0.041), but not by TAS-20 (Beta: 0.042; p=0.179). Change scores (∆) of TAS-20 and SD predicted GSIt1 (df=5, 710; TAS-20∆ Beta: -0.268; p<0.001; SD∆ Beta: 0.191; p<0.001) as well as GSI∆ (df=5, 710; TAS∆ Beta: 0.384; p<0.001; SD∆: -0.274; p<0.001) significantly. ANOVA revealed no significant interactions of TAS-20 and SD at admission on the treatment outcome (p>0.05). CONCLUSION: Low SD was shown to be a common problem of alexithymic patients and both, alexithymia and SD were highly associated with general symptom severity. SD was found to have a greater impact on treatment outcome while adjusting for baseline GSI. Alexithymia and SD act as independent factors with no significant interaction in their impact on psychopathology at admission and discharge. As different interventions were shown to improve SD scores in previous studies, SD may represent a relevant psychotherapeutic target, worthy to be addressed especially in alexithymic patients. Future studies should investigate other dimensions of the TCI, especially harm avoidance and reward dependence.

Alexithymia and brain gray matter volumes in a general population sample.

Alexithymia is perceived as a personality construct involving deficits in the cognitive processing of emotion. Brain areas that process emotions might be structurally altered in affected people. Subjects from the Study of Health in Pomerania who underwent whole body magnetic resonance imaging were investigated. After quality control procedures 2,589 subjects with Toronto Alexithymia Scale 20 (TAS-20) data and interview-based information on major depressive disorder (MDD) were available. After exclusion of study participants who were older than 65 years or had MDD in their lifetime, 1,685 subjects were included in the voxel-based morphometric (VBM 8) analyses. In whole-brain analyses, the TAS-20 total score was associated with less gray matter (GM) volumes of the bilateral dorsal anterior cingulate cortex (dACC). The TAS-20 factor scale difficulty identifying feelings (DIF) was associated with less GM volume in three clusters: dACC, left middle and inferior temporal gyrus, left fusiform gyrus and cerebellum. The lower GM volume in the left fusiform gyrus was specific for females. Absolute GM volume analyses also revealed associations between the factor scales difficulty describing feelings, external orientated thinking and the dACC. Adjustment for current symptoms of anxiety and depression did not change the effects sizes substantially. In conclusion, lower GM volume in the dACC represents the major structural correlate of alexithymia. Associations with DIF suggest a prominent involvement of left temporal areas. These areas represent language and semantic processing and might be involved in the cognitive processing of emotions and the conscious identification of feelings.

Interaction among childhood trauma and functional polymorphisms in the serotonin pathway moderate the risk of depressive disorders.

Depressive disorders are influenced by a complex interplay between genetic and environmental factors. Multiple studies support a role of serotonergic pathways in the pathophysiology of depressive disorders. As a rate-limiting enzyme of serotonin synthesis in the brain, tryptophan hydroxylase 2 (TPH2) represents a plausible candidate gene. This also applies to the serotonin reuptake transporter (5-HTTLPR) regulating the availability of serotonin in the synaptic gap. We hypothesize that functional polymorphisms (TPH2: rs7305115, 5-HTTLPR and rs25531) within both genes contribute to the risk of depressive disorders after childhood abuse in adult life. To confirm our results, we investigated two independent samples of Caucasian subjects from the study of health in Pomerania (SHIP-LEGEND: n = 2,029 and SHIP-TREND-0: n = 2,475). Depression severity was assessed by the Beck depression inventory (BDI-II) for LEGEND and the patient health questionnaire (PHQ-9) for TREND-0. Childhood abuse was assessed by the childhood trauma questionnaire. Rs7305115 (TPH2) revealed significant effects in SNP × abuse and SNP × SNP as well as in the three-way interaction. This three-way interaction among abuse, TPH2 and 5-HTTLPR showed a significant effect on depression score (p = 0.023). The SS genotype of 5-HTTLPR was associated with increased depression scores after childhood abuse only in carriers of the low-expression TPH2 GG genotype, whereas the TPH2 AA genotype reversed this effect. Our results support the role of interaction effects of genetic variants within serotonergic pathways. Genetic variants that may decrease the presynaptic serotonin concentration were associated with increased adult depressive symptoms in subjects with childhood abuse.

[18F]GE-180-PET and Post Mortem Marker Characteristics of Long-Term High-Fat-Diet-Induced Chronic Neuroinflammation in Mice.

Obesity is characterized by immoderate fat accumulation leading to an elevated risk of neurodegenerative disorders, along with a host of metabolic disturbances. Chronic neuroinflammation is a main factor linking obesity and the propensity for neurodegenerative disorders. To determine the cerebrometabolic effects of diet-induced obesity (DIO) in female mice fed a long-term (24 weeks) high-fat diet (HFD, 60% fat) compared to a group on a control diet (CD, 20% fat), we used in vivo PET imaging with the radiotracer [18F]FDG as a marker for brain glucose metabolism. In addition, we determined the effects of DIO on cerebral neuroinflammation using translocator protein 18 kDa (TSPO)-sensitive PET imaging with [18F]GE-180. Finally, we performed complementary post mortem histological and biochemical analyses of TSPO and further microglial (Iba1, TMEM119) and astroglial (GFAP) markers as well as cerebral expression analyses of cytokines (e.g., Interleukin (IL)-1ß). We showed the development of a peripheral DIO phenotype, characterized by increased body weight, visceral fat, free triglycerides and leptin in plasma, as well as increased fasted blood glucose levels. Furthermore, we found obesity-associated hypermetabolic changes in brain glucose metabolism in the HFD group. Our main findings with respect to neuroinflammation were that neither [18F]GE-180 PET nor histological analyses of brain samples seem fit to detect the predicted cerebral inflammation response, despite clear evidence of perturbed brain metabolism along with elevated IL-1ß expression. These results could be interpreted as a metabolically activated state in brain-resident immune cells due to a long-term HFD.