Low-dose interleukin 2 antidepressant potentiation in unipolar and bipolar depression: Safety, efficacy, and immunological biomarkers

Immune-inflammatory mechanisms are promising targets for antidepressant pharmacology. Immune cell abnormalities have been reported in mood disorders showing a partial T cell defect. Following this line of reasoning we defined an antidepressant potentiation treatment with add-on low-dose interleukin 2 (IL-2). IL-2 is a T-cell growth factor which has proven anti-inflammatory efficacy in autoimmune conditions, increasing thymic production of naïve CD4 + T cells, and possibly correcting the partial T cell defect observed in mood disorders. We performed a single-center, randomised, double-blind, placebo-controlled phase II trial evaluating the safety, clinical efficacy and biological responses of low-dose IL-2 in depressed patients with major depressive (MDD) or bipolar disorder (BD). 36 consecutively recruited inpatients at the Mood Disorder Unit were randomised in a 2:1 ratio to receive either aldesleukin (12 MDD and 12 BD) or placebo (6 MDD and 6 BD). Active treatment significantly potentiated antidepressant response to ongoing SSRI/SNRI treatment in both diagnostic groups, and expanded the population of T regulatory, T helper 2, and percentage of Naive CD4+/CD8 + immune cells. Changes in cell frequences were rapidly induced in the first five days of treatment, and predicted the later improvement of depression severity. No serious adverse effect was observed. This is the first randomised control trial (RCT) evidence supporting the hypothesis that treatment to strengthen the T cell system could be a successful way to correct the immuno-inflammatory abnormalities associated with mood disorders, and potentiate antidepressant response.

Choroid plexus volume is increased in mood disorders and associates with circulating inflammatory cytokines

Depressed patients exhibit altered levels of immune-inflammatory markers both in the peripheral blood and in the cerebrospinal fluid (CSF) and inflammatory processes have been widely implicated in the pathophysiology of mood disorders. The Choroid Plexus (ChP), located at the base of each of the four brain ventricles, regulates the exchange of substances between the blood and CSF and several evidence supported a key role for ChP as a neuro-immunological interface between the brain and circulating immune cells. Given the role of ChP as a regulatory gate between periphery, CSF spaces and the brain, we compared ChP volumes in patients with bipolar disorder (BP) or major depressive disorder (MDD) and healthy controls, exploring their association with history of illness and levels of circulating cytokines. Plasma levels of inflammatory markers and MRI scans were acquired for 73 MDD, 79 BD and 72 age- and sex-matched healthy controls (HC). Patients with either BD or MDD had higher ChP volumes than HC. With increasing age, the bilateral ChP volume was larger in patients, an effect driven by the duration of illness; while only minor effects were observed in HC. Right ChP volumes were proportional to higher levels of circulating cytokines in the clinical groups, including IFN-γ, IL-13 and IL-17. Specific effects in the two diagnostic groups were observed when considering the left ChP, with positive association with IL-1ra, IL-13, IL-17, and CCL3 in BD, and negative associations with IL-2, IL-4, IL-1ra, and IFN-γ in MDD. These results suggest that ChP could represent a reliable and easy-to-assess biomarker to evaluate the brain effects of inflammatory status in mood disorders, contributing to personalized diagnosis and tailored treatment strategies.

Circulating cytotoxic immune cell composition, activation status and toxins expression associate with white matter microstructure in bipolar disorder

Patients with bipolar disorder (BD) show higher immuno-inflammatory setpoints, with in vivo alterations in white matter (WM) microstructure and post-mortem infiltration of T cells in the brain. Cytotoxic CD8+ T cells can enter and damage the brain in inflammatory disorders, but little is known in BD. Our study aimed to investigate the relationship between cytotoxic T cells and WM alterations in BD. In a sample of 83 inpatients with BD in an active phase of illness (68 depressive, 15 manic), we performed flow cytometry immunophenotyping to investigate frequencies, activation status, and expression of cytotoxic markers in CD8+ and tested for their association with diffusion tensor imaging (DTI) measures of WM microstructure. Frequencies of naïve and activated CD8+ cell populations expressing Perforin, or both Perforin and Granzyme, negatively associated with WM microstructure. CD8+ Naïve cells negative for Granzyme and Perforin positively associates with indexes of WM integrity, while the frequency of CD8+ memory cells negatively associates with index of WM microstructure, irrespective of toxins expression. The resulting associations involve measures representative of orientational coherence and myelination of the fibers (FA and RD), suggesting disrupted oligodendrocyte-mediated myelination. These findings seems to support the hypothesis that immunosenescence (less naïve, more memory T cells) can detrimentally influence WM microstructure in BD and that peripheral CD8+ T cells may participate in inducing an immune-related WM damage in BD mediated by killer proteins.

Association between NTRK2 Polymorphisms, Hippocampal Volumes and Treatment Resistance in Major Depressive Disorder

Despite the increasing availability of antidepressant drugs, a high rate of patients with major depression (MDD) does not respond to pharmacological treatments. Brain-derived neurotrophic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling is thought to influence antidepressant efficacy and hippocampal volumes, robust predictors of treatment resistance. We therefore hypothesized the possible role of BDNF and neurotrophic receptor tyrosine kinase 2 (NTRK2)-related polymorphisms in affecting both hippocampal volumes and treatment resistance in MDD. A total of 121 MDD inpatients underwent 3T structural MRI scanning and blood sampling to obtain genotype information. General linear models and binary logistic regressions were employed to test the effect of genetic variations related to BDNF and NTRK2 on bilateral hippocampal volumes and treatment resistance, respectively. Finally, the possible mediating role of hippocampal volumes on the relationship between genetic markers and treatment response was investigated. A significant association between one NTRK2 polymorphism with hippocampal volumes and antidepressant response was found, with significant indirect effects. Our results highlight a possible mechanistic explanation of antidepressant action, possibly contributing to the understanding of MDD pathophysiology.

Melatonin secretion patterns are associated with cognitive vulnerability and brain structure in bipolar depression

Circadian rhythm disruption is a core symptom of bipolar disorder (BD), also reflected in altered patterns of melatonin release. Reductions of grey matter (GM) volumes are well documented in BD. We hypothesized that levels and timing of melatonin secretion in bipolar depression could be associated with depressive psychopathology and brain GM integrity. The onset of melatonin secretion under dim light conditions (DLMO) and the amount of time between DLMO and midsleep (i.e. phase angle difference; PAD) were used as circadian rhythm markers. To study the time course of melatonin secretion, an exponential curve fitting the melatonin values was calculated, and the slope coefficients (SLP) were obtained for each participant. Significant differences were found between HC and BD in PAD measures and melatonin profiles. Correlations between PAD and depressive psychopathology were identified. Melatonin secretion patterns were found to be associated with GM volumes in the Striatum and Supramarginal Gyrus in BD. Our findings emphasized the role of melatonin secretion role as a biological marker of circadian synchronization in bipolar depression and provided a novel insight for a link between melatonin release and brain structure.

Insulin resistance disrupts white matter microstructure and amplitude of functional spontaneous activity in bipolar disorder

BACKGROUND

Bipolar disorder (BD) is linked to several structural and functional brain alterations. In addition, BD patients have a three-fold increased risk of developing insulin resistance, which is associated with neural changes and poorer BD outcomes. Therefore, we investigated the effects of insulin and two derived measures (insulin resistance and sensitivity) on white matter (WM) microstructure, resting-state (rs) functional connectivity (FC), and fractional amplitude of low-frequency fluctuation (fALFF).

METHODS

BD patients (n = 92) underwent DTI acquisition, and a subsample (n = 22) underwent rs-fMRI. Blood samples were collected to determine insulin and glucose levels. The Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) were computed. DTI data were analyzed via tract-based spatial statistics and threshold-free cluster enhancement. From rs-fMRI data, both ROI-to-ROI FC matrices and fALFF maps were extracted.

RESULTS

Insulin showed a widespread negative association with fractional anisotropy (FA) and a positive effect on radial diffusivity (RD) and mean diffusivity (MD). HOMA-IR exerted a significant effect on RD in the right superior longitudinal fasciculus, whereas QUICKI was positively associated with FA and negatively with RD and MD in the left superior longitudinal fasciculus, left anterior corona radiata, and forceps minor. fALFF was negatively modulated by insulin and HOMA-IR and positively associated with QUICKI in the precuneus. No significant results were found in the ROI-to-ROI analysis.

CONCLUSION

Our findings suggest that WM microstructure and functional alterations might underlie the effect of IR on BD pathophysiology, even if the causal mechanisms need to be further investigated.

Long-term effect of childhood trauma: Role of inflammation and white matter in mood disorders

Bipolar disorder (BD) and major depressive disorder (MDD) are severe psychiatric illnesses that share among their environmental risk factors the exposure to adverse childhood experiences (ACE). Exposure to ACE has been associated with long-term changes in brain structure and the immune response. In the lasts decades, brain abnormalities including alterations of white matter (WM) microstructure and higher levels of peripheral immune/inflammatory markers have been reported in BD and MDD and an association between inflammation and WM microstructure has been shown. However, differences in these measures have been reported by comparing the two diagnostic groups. The aim of the present study was to investigate the interplay between ACE, inflammation, and WM in BD and MDD. We hypothesize that inflammation will mediate the association between ACE and WM and that this will be different in the two groups. A sample of 200 patients (100 BD, 100 MDD) underwent 3T MRI scan and ACE assessment through Childhood Trauma Questionnaire. A subgroup of 130 patients (75 MDD and 55 BD) underwent blood sampling for the assessment of immune/inflammatory markers. We observed that ACE associated with higher peripheral levels of IL-2, IL-17, bFGF, IFN-γ, TNF-α, CCL3, CCL4, CCL5, and PDGF-BB only in the BD group. Further, higher levels of CCL3 and IL-2 associated with lower FA in BD. ACE were found to differently affect WM microstructure in the two diagnostic groups and to be negatively associated with FA and AD in BD patients. Mediation analyses showed a significant indirect effect of ACE on WM microstructure mediated by IL-2. Our findings suggest that inflammation may mediate the detrimental effect of early experiences on brain structure and different mechanisms underlying brain alterations in BD and MDD.

Selective association of cytokine levels and kynurenine/tryptophan ratio with alterations in white matter microstructure in bipolar but not in unipolar depression

Bipolar (BD) and major depression (MDD) disorders are severe mental illnesses characterised by altered levels of immune/inflammatory markers and disrupted white matter (WM) microstructure. A pro-inflammatory state was suggested to activate indoleamine 2,3-dioxygenase which, in turn, increases the amount of tryptophan (Trp) converted into kynurenine (Kyn). We investigated whether plasma levels of Trp, Kyn and Kyn/Trp ratio are associated with peripheral levels of immune/inflammatory markers and whether they are related to WM integrity in 100 MDD and 66 BD patients. Patients also underwent MRI, and fractional anisotropy (FA) was estimated as a measure of WM microstructure. BD patients showed higher Kyn levels and Kyn/Trp ratio than MDD patients, and lower FA in several WM tracts, including the corpus callosum and the inferior fronto-occipital fasciculus (IFO). Lower Trp levels associated with a more severe depressive symptomatology irrespective of diagnosis and with lower FA in the corpus callosum (CC) and external capsule (EC). We found an association of immune/inflammatory markers with Kyn/Trp ratio selectively in BD patients: IL-1β and TNF-α showed a positive relationship and IL-2 and IL-9 a negative relationship; in addition, higher IL-4 correlated with lower Kyn levels; higher Kyn/Trp ratio and IL-1β correlated with lower FA in the CC and IFO. Notably, the detrimental effect of IL-1β on the IFO was moderated by the Kyn/Trp ratio. These data suggest that in BD, cytokines and the conversion of Trp into Kyn may affect WM microstructure and support the idea that distinct mechanisms underlie the pathophysiology of BD and MDD.

Cognition in Schizophrenia: Modeling the Interplay between Interleukin-1β C-511T Polymorphism, Metabolic Syndrome, and Sex

INTRODUCTION

Cognitive deficits and metabolic disturbances are among the main determinants of functional impairment and reduced life expectancy in patients with schizophrenia, and they may share underlying biological mechanisms. Among these, interleukin-1β (IL-1β), a key mediator of inflammatory response, is of particular interest. IL-1β C-511T polymorphism has been associated with neuropsychiatric conditions and, in the general population, with cognitive and metabolic alterations. This study aims to evaluate the effects of the IL-1β C-511T polymorphism on both cognition and metabolic syndrome in a sample of patients affected by schizophrenia, with a focus on sex differences.

METHODS

138 patients with schizophrenia were assessed for metabolic parameters and neurocognitive measures by means of the Brief Assessment of Cognition Scale. The effects of IL-1β C-511T polymorphism on cognition and metabolic syndrome were evaluated in the context of general linear models.

RESULTS

The analysis showed a significant interaction between IL-1β genotype and sex on 2 core cognitive domains. In detail, among CC homozygous, females outperformed males on processing speed, while among T carriers, males outperformed females on executive functions. A significant interaction also emerged between metabolic syndrome, sex, and IL-1β genotype for executive functions, with worse performance for T carrier females with metabolic syndrome. No significant direct effect was observed for metabolic syndrome on cognition.

CONCLUSION

These findings support the hypothesis that IL-1β polymorphism could play a key role in mediating the complex and refined relationship between metabolic syndrome and cognitive performance.

Adiponectin predicts poor response to antidepressant drugs in major depressive disorder

OBJECTIVE

Produced by adipocytes, adiponectin crosses the blood-brain barrier to bind with specific receptors in the hypothalamus, brainstem, hippocampus, and cortex. In patients with major depressive disorder (MDD), circulating levels of adiponectin inversely related with antidepressant response to ketamine, and predicted a better response to multi-target drug combinations than to escitalopram. We investigated the effect of adiponectin on response to antidepressants in a naturalistic setting.

METHODS

We assessed baseline plasma levels of adiponectin in 121 MDD inpatients, treated with antidepressant drug monotherapy based on clinical need (selective serotonin reuptake inhibitors, venlafaxine, duloxetine) in a specialized hospital setting. Severity of depression was weekly assessed with Hamilton scale ratings.

RESULTS

Adiponectin plasma levels were higher in patients with MDD compared with healthy controls, and negatively influenced the pattern of antidepressant response (higher baseline levels, worse response) independent of the drug class and of the baseline severity of depression, and of age, sex, and body mass index.

CONCLUSIONS

The identification of adiponectin as a predictor of antidepressant response to drugs of different mechanism of action, such as ketamine, SSRIs, and SNRIs, and both in experimental and in clinical settings, warrants interest for further study of its pathways to search for novel biomarkers and therapeutic targets.

Effective Antidepressant Chronotherapeutics (Sleep Deprivation and Light Therapy) Normalize the IL-1β:IL-1ra Ratio in Bipolar Depression

Background

Mood disorders associate with peripheral markers of low-grade inflammation, among which circulating levels of interleukin-1β (IL-1β) consistently predict diagnosis and poor outcomes. Antidepressant chronotherapeutics (total sleep deprivation and light therapy, TSD+LT) prompts response in drug-resistant bipolar depression, but its effect on peripheral inflammation were never assessed. Here we explored the effects of TSD+LT on IL-1β signaling.

Methods

We studied the ratio between IL-1β and its receptor antagonist (IL-1β:IL1ra) in 33 healthy participants, and in 26 inpatients with a major depressive episode in course of Bipolar Disorder, before and after treatment with three cycles of repeated TSD+LT, interspersed with sleep recovery nights, administered during 1 week. Treatment effects of mood and on IL-1β:IL1ra were analyzed in the context of the Generalized Linear Model (GLM).

Results

At baseline, patients had higher IL-1β, IL1ra, and IL-1β:IL1ra than controls. Treatment significantly decreased IL-1β:IL1ra, by decreasing IL-1β and increasing IL1ra, the effect being proportional to baseline levels and normalizing values. Patients with higher baseline levels showed the highest decrease in IL-1β:IL-1ra, which associated with the immediate antidepressant response at the first cycle; while patients with lower baseline values showed negligible changes in the IL-1β:IL-1ra, unrelated to treatment response.

Conclusion

We observed a parallel change of inflammatory biomarkers and severity of depression after chronotherapeutics, suggesting that a reduction in inflammation associated with depression could contribute to the mechanism of action of TSD+LT, and warranting interest for controlled studies addressing the role of inflammation in the recovery from bipolar depression.

Circulating inflammatory markers impact cognitive functions in bipolar depression

BACKGROUND

Cognitive impairment is a core feature of bipolar disorder, with a prevalence of about 64.4% during episodes and 57.1% in euthymia. Recent evidences suggest that cognitive deficits in BD may follow immune dysfunction and elevated levels of inflammatory cytokines have been reported during periods of depression, mania and euthymia, suggesting the presence of a chronic, low-grade inflammatory state. The aim of the study is to investigate if immune/inflammatory markers and especially chemokines associate to cognitive performances.

METHODS

Seventy-six consecutively admitted inpatients with a depressive episode in course of bipolar disorder performed a neuropsychological evaluation with the Brief Assessment of Cognition in Schizophrenia and plasma blood levels of cytokines, chemokines and growth factors were analyzed with Luminex technology.

RESULTS

Higher levels of IL-1β, IL-6, CCL2, CCL4, CCL5, CXCL10, and bFGF are associated with the likelihood of having a poor cognitive performance.

LIMITATIONS

Limitation include the lack of a group of healthy controls and the lack of information regarding previous psychopharmacological treatments, alcohol and tobacco use.

CONCLUSIONS

Our results confirm the importance of chemokines in bipolar disorder and suggest that inflammatory markers suggestive of a low-grade inflammatory state could contribute to the neurocognitive deficits observed in depressed patients.

The role of periodontal bacteria, Porphyromonas Gingivalis, in Alzheimer's disease pathogenesis and aggravation: a review

The aim of this study was to establish the role of Porphyromonas gingivalis in Alzheimer's disease. An electronic search of publications was established from three electronic databases: Cochrane, PubMed and Web of Science. The search strategy used a combination of controlled vocabulary and free-text words. Inclusion and exclusion criteria were defined by the authors before the start of the study. The inclusion criteria were: all studies published in English language; in vitro analysis; in vivo on animals and postmortem biopsies on humans; studies analyzing the correlation between periodontal disease and Alzheimer. The search resulted in 262 titles. Only 9 articles were included in the quantitative analysis. An inflammatory status in the oral cavity might be connect to a brain degeneration syndrome such as dementia and AD. However, a strictly connection is still not evincible. More trials are recommended in order to investigate the role of periodontal bacteria and Porphyromonas gingivalis in AD pathogenesis and aggravation.

Upper-lip laser frenectomy with a diode laser in a pediatric patient: a case report

The case report aims to describe the parameters of performing upper labial frenectomy with the use of diode laser beams without infiltrated local anaesthesia. A 6-year-old patient was referred by the orthodontist for assessment of the upper anterior labial frenum. The dental treatment plan reported only the presence of caries on deciduous teeth and seals on the first permanent molars. The clinical examination reported the presence of a high attachments of labial frenum with a pathologically attachment and the presence of a diastema supports this theory. The laser used to remove the frenulum was a diode laser used with a wavelength of 980 nm with 320 microns of fiber in contact with a power of 2.0 W in continuous wave mode. The clinical examination showed an acceptable healing by secondary intention of the wound and the initial functional recovery of a physiological upper lip movements. The patient reported that the procedure was well tolerated. The diode laser can be used with good result for the removal of pathological frenum. The diode laser can be used in pediatric dentistry because of its application, adequate coagulation, no need for sutures and less inflammation and pain.

Short implants (≤6mm) as an alternative treatment option to maxillary sinus lift

The aim of this systematic review was to evaluate survival rate of short dental implants placed in the posterior area of the maxilla. The electronic literature search of studies published between January 1, 2010 and February 29, 2020 was performed using specific word combinations. The outcome was to meta-analyse the implant survival rate (ISR). The search generated 238 potential studies. After screening procedures, only nine randomized controlled trials fulfilled the inclusion criteria and were selected for qualitative and quantitative analysis. ISR of short implants ranged from 91.9% to 100%, while standard-length implants ISR ranged from 82.9% to 100% with a follow-up from 1 to 5 years in function. The risk ratio difference was 1.24 (95% confidence interval: 0.63-2.45, P=0.52) for short dental implants failure when compared with standard dental implants, and was not statistically significant. Based on the evidence of the included studies, short implants (≤6mm) reported high survival rates over short to medium follow-up in posterior maxilla, but the long-term success is as yet not demonstrated.

Higher baseline interleukin-1β and TNF-α hamper antidepressant response in major depressive disorder

Raised pro-inflammatory immune/inflammatory setpoints, leading to an increased production of peripheral cytokines, have been associated with Major Depressive Disorder (MDD) and with failure to respond to first-line antidepressant drugs. However, the usefulness of these biomarkers in clinical psychopharmacology has been questioned because single findings did not translate into the clinical practice, where patients are prescribed treatments upon clinical need. We studied a panel of 27 inflammatory biomarkers in a sample of 108 inpatients with MDD, treated with antidepressant monotherapy for 4 weeks upon clinical need in a specialized hospital setting, and assessed the predictive effect of baseline peripheral measures of inflammation on antidepressing efficacy (response rates and time-lagged pattern of decrease of depression severity) using a machine-learning approach with elastic net penalized regression, and multivariate analyses in the context of the general linear model. When considering both categorical and continuous measures of response, baseline levels of IL-1β predicted non-response to antidepressants, with the predicted probability to respond being highly dispersed at low levels of IL-1β, and stratifying toward non-response when IL-1β is high. Significant negative effects were also detected for TNF-α, while IL-12 weakly predicted response. These findings support the usefulness of inflammatory biomarkers in the clinical psychopharmacology of depression, and add to ongoing research efforts aiming at defining reliable cutoff values to identify depressed patients in clinical settings with high inflammation, and low probability to respond.

Diode laser as an adjunct to nonsurgical chronic periodontitis therapy: a review

The aim of this review was to investigate the additional effects of diode laser irradiation in combination with nonsurgical periodontal therapy. An electronic search of publications was established from three electronic databases: Cochrane, PubMed and Web of Science. The search strategy used a combination of controlled vocabulary and free-text words. Inclusion and exclusion criteria were defined by the authors before the start of the study. The inclusion criteria were all studies published in English language, randomized controlled trials, based on human subjects. All trials were designed to evaluate the efficacy of the diode laser therapy as an adjunct to nonsurgical periodontal therapy in the treatment of chronic periodontitis patients. All studies analyzed are not older than five years. The search resulted in 188 titles. After the analysis of the abstracts, an article was excluded because it was not relevant for the study and two because it treated aggressive periodontitis. At the end only 6 articles were included in the qualitative analysis. The potential role in chronic periodontal disease treatment of diode laser is still not demonstrated. Several studies regard the diode laser therapy, but there is still heterogeneity for what it concerns research and clinical protocols. As a result, several randomized controlled trials are needed to obtain certain data.

A single nucleotide polymorphism in SLC1A1 gene is associated with age of onset of obsessive-compulsive disorder

Different genetic polymorphisms in the SLC1A1 have been shown to be associated with obsessive-compulsive disorder. Rs301430 is a T/C functional polymorphism affecting the gene expression and extrasynaptic glutamate concentration.We observed that Rs301430 influence age at onset in obsessive-compulsive disorder.

Cortico-limbic functional connectivity mediates the effect of early life stress on suicidality in bipolar depressed 5-HTTLPR*s carriers

BACKGROUND

In bipolar disorder (BD) the risk of suicide in adult life can be influenced by the interaction of adverse childhood experiences with the serotonin transporter polymorphism (5-HTTLPR). The cortico-limbic connectivity is a candidate endophenotype for the disorder, also related to suicidality and affected by the 5-HT system.

METHODS

In 64 (*s carriers = 41; l/l = 23) depressed BD patients, we explored the effect of 5-HTTLPR on corticolimbic functional connectivity (FC) during emotional processing, and the role of FC in moderating/mediating the effect of early stressful events on suicidality among 5-HTTLPR groups, by implementing Generalized Structural Equation Model.

RESULTS

5-HTTLPR affects FC between amygdala (Amy) and anterior cingulate cortex (ACC), temporal pole, putamen/thalamus, and precuneus. The short allele was associated to a more inefficient corticolimbic connectivity. In 5-HTTLPR*s carriers, but not in l/l, the Amy-ACC functional coupling mediated the relationship between stress load and current suicidality.

LIMITATIONS

Patients were not drug-naive, and the recruitment took place in a single center, thus raising the possibility of population stratifications. The sample size is relatively small, but our findings can provide the background for replication study in independent and larger datasets.

CONCLUSIONS

Our results confirm the link between the 5-HTT promoter polymorphism and susceptibility to stress in BD, and suggest that cortico-limbic functional connectivity mediates these effects. This pattern could identify a vulnerability factor for the exacerbation of mood episodes after stressful life events particularly relevant in *s carriers.

Proinflammatory Cytokines Predict Brain Metabolite Concentrations in the Anterior Cingulate Cortex of Patients With Bipolar Disorder

Bipolar disorder (BD) is a severe psychiatric illness characterized by abnormalities in the immune/inflammatory function and in brain metabolism. Evidences suggest that inflammation may affect the levels of brain metabolites as measured by single-proton magnetic resonance spectroscopy (¹H-MRS). The aim of the study was to investigate whether a wide panel of inflammatory markers (i.e., cytokines, chemokines, and growth factors) can predict brain metabolite concentrations of glutamate, myo-inositol, N-acetylaspartate, and glutathione in a sample of 63 bipolar patients and 49 healthy controls. Three cytokines influenced brain metabolite concentrations: IL-9 positively predicts glutamate, IL-1β positively predicts Myo-inositol, and CCL5 positively predicts N-acetylaspartate concentrations. Furthermore, patients showed higher concentrations of glutamate, Myo-inositol, and glutathione and lower concentrations of N-acetylaspartate in respect to healthy controls. Our results confirm that inflammation in BD alters brain metabolism, through mechanisms possibly including the production of reactive oxygen species and glia activation.

Comparison of the accuracy of intraoral scanning and conventional impression techniques on implants: a review

The aim of this review was to collect available evidence and evaluate accuracy outcomes of dental implant impression techniques, and to compare the accuracy of conventional implant impression versus digital implant impression. Inclusion and exclusion criteria were defined by the authors before the start of the study. The inclusion criteria were: all studies published in English language; studies no older than five years; analyzing the accuracy of digital vs conventional technique impression on implants. The exclusion criteria were: publications that reported the same data as later publications by the same authors and systematic reviews; commentaries and letters to the editor; case report and case series. The search resulted in 106 titles. Following the first stage of screening, after the records identification through database manual searching, 112 potentially relevant studies were identified. After the second stage screening, 33 full text publications were obtained and analyzed and 17 were excluded. Afterwards, 18 articles resulted eligible after full text reading and a cross search of the articles' references was accomplished; 3 articles were consequently added. At the end only 7 articles were included in the quantitative analysis. Within the limitations of this systematic review, digital impression on dental implants offers a comparable accuracy compared with conventional impressions technique. More clinical trials are recommended to investigate the accuracy of these scanners and their validity in clinical use.

Fit evaluation of cad/cam fabricated all-ceramic restorations based on direct and indirect digitalization in vivo: a systematic review

The aim of this study was to compare the fit of all-ceramic restorations on natural teeth fabricated through a direct digital workflow or an indirect digital workflow. An electronic search of publications was established from three electronic databases: Cochrane, PubMed and Web of Science. The search strategy used a combination of controlled vocabulary and free-text words. The detailed search design and strategies, including keywords, are presented below. The authors used two filters to follow data for the research: papers written in English and published in the last 5 years. The search resulted in 3042 titles. Following the first stage of screening, after the records identification through database manual searching, 3047 potentially relevant studies were identified. After the second stage screening, 38 full text publications were obtained and analyzed and 17 were excluded. Afterwards, 22 articles resulted eligible after full text reading and a cross search of the articles references was accomplished and 5 articles were consequently added. At last, 6 articles were included in the quantitative analysis. This study was designed to compare the fit of restorations obtained by means of a direct or indirect digital workflow. The values reported on the maximum acceptable gap in scientific literature range from 50 to 200 μm, so there does not seem to be an objective limit based on scientific evidence. According to the most accepted marginal discrepancy in the literature, most of the values of the studies examined are in the 200 μm acceptability range. Within the limitations of this systematic review, computer-aided design and computer-aided manufacturing (CAD/CAM) fabricated restorations obtained by means of an intraoral scanner (IOS) showed better marginal and internal fit than restorations obtained through conventional impression and subsequent laboratory scanning. According to the results of this systematic review, the direct digital workflow resulted as a valid alternative to the indirect digital workflow to produce CAD/CAM all-ceramic restorations.

Radiosurgery in dentistry: a review

The aim of the present study was to analyse the clinical potential of radiosurgery applied to modern dentistry through a revision of the indexed literature. Radiosurgery represents a recent form of electrosurgery working at a frequency of 3.0-4.0 MHz. The depth of penetration of the waves is inversely proportional to the frequency. Radiowaves working at high frequency express a lower penetration with a consequent lower tissue alteration. The authors analyzed the literature in order to give to the scientific community an overview of the possible applications of radiosurgery in the clinical dental practice and their effectiveness. Radiosurgery can be used in prosthodontics, in periodontal and implant surgery, in the treatment of trigeminal neuralgia, in the treatment of obstructive sleep apnea syndromes (OSAS) and in endodontics. Our analysis shows that although there are few articles in indixed literature on the applications of radiosurgery in dentistry, thanks to the benefits that derive from it, radiosurgery will spread more in the daily clinical practice of the dentists.

Neurobiology of cognitive remediation in schizophrenia: Effects of EAAT2 polymorphism

Cognitive deficits represent core features of schizophrenia, affecting quality of life and functioning. The excitatory amino acid transporter 2 (EAAT2) is responsible for the majority of glutamate reuptake and its activity is crucial for glutamatergic neurotransmission, prevention of excitotoxic damage and cerebral metabolism. Different studies reported that EAAT2 rs4354668 (-181 T/G) influences cognitive functions and brain structures in patients with schizophrenia. Specifically, the G allele, linked to lower EAAT2 expression, was associated with impaired prefrontal cognitive performance and reduced grey matter volumes. Cognitive remediation therapy (CRT) is one of the best available tool to treat cognitive deficits in schizophrenia, able to induce a neuroplastic modulation of cognitive functions. The present study aims to investigate the effects of rs4354668 on CRT outcome, also considering possible genotype interaction with antipsychotic (AP) treatment, since EAAT2 expression is negatively influenced by clozapine. We examined rs4354668 in 88 clinically stabilized patients with schizophrenia, treated with CRT and assessed at enrolment, at the end of CRT and after 3 months. We observed greater working memory improvements among patients carrying the T/T genotype, regardless of AP treatment. Moreover, we reported a significant interaction between pharmacological treatment and rs4354668 on executive functions, with greater improvements among T/T patients treated with APs other than clozapine. These observations suggest that impaired EAAT2 expression may attenuate CRT outcome. Moreover, our results indicate the possibility that rs4354668 could also differentially influence the response to CRT depending on the AP treatment.

A Glutamate Transporter EAAT1 Gene Variant Influences Amygdala Functional Connectivity in Bipolar Disorder

Bipolar disorder (BD) is a severe illness characterized by recurrent depressive and manic episodes and by emotional dysregulation. Altered cortico-limbic connectivity could account for typical symptoms of the disorder such as mood instability, emotional dysregulation, and cognitive deficits. Functional connectivity positively associated with glutamatergic neurotransmission. The inactivation of glutamate is handled by a series of glutamate transporters, among them, the excitatory amino acid transporter 1 (EAAT1) which is modulated by a SNP rs2731880 (C/T) where the C allele leads to increased EAAT1 expression and glutamate uptake. We hypothesized that rs2731880 would affect cortico-limbic functional connectivity during an implicit affective processing task. Sixty-eight BD patients underwent fMRI scanning during implicit processing of fearful and angry faces. We explored the effect of rs2731880 on the strength of functional connectivity from the amygdalae to the whole brain. A significant activation in response to emotional processing was observed in two main clusters encompassing the right and left amygdala. Amygdalae to whole-brain functional connectivity analyses revealed a significant interaction between rs2731880 and the task (emotional stimuli vs geometric shapes) for the functional connections between the right amygdala and right subgenual anterior cingulate cortex. Post-hoc analyses revealed that T/T patients showed a significant negative connectivity between the amygdala and anterior cingulate cortex compared to C carriers. T/T subjects also performed significantly better in the face-matching task than rs2731880*C carriers. Our findings reveal an EAAT1 genotype-associated difference in cortico-limbic connectivity during affective regulation, possibly identifying a neurobiological underpinning of emotional dysfunction in BD.

Radiosurgery-assisted gingival displacement: a proof of concept technique to enhance the efficiency of intraoral digital impression

Nowadays, an increasing number of dentists are using intraoral scanners (IOS) in their daily practice as an alternative to conventional impression taking. One of the main concerns is related to the capability of scanning the subgingival anatomy of the die, usually very challenging due to the limited operative field and the presence of oral fluids. The radiosurgery assisted gingival displacement technique (RAGD) may enhance the intraoral optical scanning of the finish line and neighbor tooth anatomy. The contour of the interim prosthesis is used to drive the tip of radiosurgery electrode along the tooth surface and open selectively the gingival crevice with a prosthetically-driven and minimally invasive approach. The clinical implication of this technique is related to increasing the efficiency and accuracy of the digital impression technique in the critical zone of the prosthetic shoulder.

The effect of childhood trauma on serum BDNF in bipolar depression is modulated by the serotonin promoter genotype

In healthy humans, both childhood trauma and the short form of the serotonin promoter transporter genotype (5-HTTLPR) are associated with lower levels of brain-derived neurotrophic factor (BDNF). In subjects with bipolar disorder (BD), lower levels of BDNF and a higher degree of childhood trauma were observed compared with healthy controls. However, is still unknown if the functional 5-HTTLPR polymorphisms exerts an effect on both abnormalities. In 40 inpatients affected by a major depressive episode in the course of BD, we genotyped 5-HTTLPR, measured serum BDNF with ELISA, and assessed early adversities by the childhood trauma questionnaire (CTQ). Data were analyzed in the context of the general linear model correcting for age, sex, ongoing lithium treatment, severity of current depression, and CTQ minimization/denial scores to investigate the effect of 5-HTTLPR polymorphism and childhood trauma on BDNF levels. Early trauma were negatively associated with BDNF serum levels (higher CTQ scores, lower BDNF; p=0.0019). 5-HTTLPR l/l homozygotes showed significantly higher BDNF levels than 5-HTTLPR*s carriers (30.57±6.13 vs 26.82±6.41; p=0.0309). A separate-slopes analysis showed that 5-HTTLPR significantly influenced the relationship between early trauma and adult BDNF (interaction of 5-HTTLPR with CTQ scores: p=0.0023), due to a significant relationship between trauma and BDNF in 5-HTTLPR*s carriers, but not among l/l homozygotes. Putatively detrimental effects of childhood trauma exposure on adult BDNF serum levels are influenced by 5-HTTLPR genotype in patients affected by BD. Possible mechanisms include epigenetic modulation of BDNF gene expression, due to different reactivity to stressors in 5-HTTLPR genotype groups.

Catechol-O-methyltransferase Val(108/158)Met polymorphism affects fronto-limbic connectivity during emotional processing in bipolar disorder

Catechol-O-methyltransferase (COMT) inactivates catecholamines, Val/Val genotype was associated to an increased amygdala (Amy) response to negative stimuli and can influence the symptoms severity and the outcome of bipolar disorder, probably mediated by the COMT polymorphism (rs4680) interaction between cortical and subcortical dopaminergic neurotransmission. The aim of this study is to explore how rs4680 and implicit emotional processing of negative emotional stimuli could interact in affecting the Amy connectivity in bipolar depression. Forty-five BD patients (34 Met carriers vs. 11 Val/Val) underwent fMRI scanning during implicit processing of fearful and angry faces. We explore the effect of rs4680 on the strength of functional connectivity from the amygdalae to whole brain. Val/Val and Met carriers significantly differed for the connectivity between Amy and dorsolateral prefrontal cortex (DLPFC) and supramarginal gyrus. Val/Val patients showed a significant positive connectivity for all of these areas, where Met carriers presented a significant negative one for the connection between DLPFC and Amy. Our findings reveal a COMT genotype-dependent difference in corticolimbic connectivity during affective regulation, possibly identifying a neurobiological underpinning of clinical and prognostic outcome of BD. Specifically, a worse antidepressant recovery and clinical outcome previously detected in Val/Val patients could be associated to a specific increased sensitivity to negative emotional stimuli.

Full digital workflow for implant-prosthetic rehabilitations: a case report

OBJECTIVES

The aim of the present study was to describe a proof of concept digital workflow for the implant-prosthetic treatment in partially edentate patients and evaluate its clinical performance.

METHODS

A 55-year-old woman with a Kennedy class III bilateral edentulism in the mandible has been selected for a computer guided implantology according with the Smart Fusion® protocol (NobelBiocare, Kloten, Switzerland). After the template-guided implant placement, an immediate loading of the implants has been performed. QuickTemp conical temporary abutments were selected to deliver immediately prefabricated cement-retained provisionals. Two months after an impression was taken with an intraoral digital scanner (3Shape Trios3, Copenhagen, Denmark). The provisional restoration optical scanning was used to transfer the functionalized prosthetic contour to be duplicated into the definitive porcelain fused to zirconia restoration cemented on customized titanium abutments.

RESULTS

A satisfying esthetic and functional result has been achieved. No biological and mechanical complications were recorded.

CONCLUSIONS

The investigated fully digital implant-prosthetic protocol provided a smooth, complication free and time effective treatment alternative to the conventional workflow. Besides the fully digital workflow allowed the surgical and prosthetic decision making and the communication within the dental team and with the patient. Further improvements heading to a direct match between the intraoral scan and the CBCT are strongly advised in order to create the so-called virtual patient.

Sleep homeostatic pressure and PER3 VNTR gene polymorphism influence antidepressant response to sleep deprivation in bipolar depression

BACKGROUND

Combined Total sleep deprivation (TSD) and light therapy (LT) cause a rapid improvement in bipolar depression which has been hypothesized to be paralleled by changes in sleep homeostasis. Recent studies showed that bipolar patients had lower changes of EEG theta power after sleep and responders to antidepressant TSD+LT slept less and showed a lower increase of EEG theta power then non-responders. A polymorphism in PER3 gene has been associated with diurnal preference, sleep structure and homeostatic response to sleep deprivation in healthy subjects. We hypothesized that the individual variability in the homeostatic response to TSD could be a correlate of antidepressant response and be influenced by genetic factors.

METHODS

We administered three TSD+LT cycles to bipolar depressed patients. Severity of depression was rated on Hamilton Depression Rating Scale. Actigraphic recordings were performed in a group of patients.

RESULTS

PER3 polymorphism influenced changes in total sleep time (F=2.24; p=0.024): while PER3(4/4) and PER3(4/5) patients showed a reduction in it after treatment, PER3(5/5) subjects showed an increase of about 40min, suggesting a higher homeostatic pressure. The same polymorphism influenced the change of depressive symptomatology during treatment (F=3.72; p=0.028).

LIMITATIONS

Sleep information was recorded till the day after the end of treatment: a longer period of observation could give more information about the possible maintenance of allostatic adaptation.

CONCLUSIONS

A higher sleep homeostatic pressure reduced the antidepressant response to TSD+LT, while an allostatic adaptation to sleep loss was associated with better response. This process seems to be under genetic control.

Sterol Regulatory Element Binding Transcription Factor-1 Gene Variation and Medication Load Influence White Matter Structure in Schizophrenia

BACKGROUND

Diffusion tensor imaging (DTI) studies have shown a widespread disruption of white matter (WM) microstructure in schizophrenia. Furthermore, higher fractional anisotropy (FA) has been consistently correlated with the severity of psychotic symptoms. Antipsychotic drugs (APDs) affect lipid homeostasis. Gene polymorphisms in sterol regulatory element binding transcription factor (SREBF)-1 and SREBF-2 have been associated with schizophrenia.

METHODS

In a sample of 65 patients affected by chronic schizophrenia, we investigated the effect of ongoing APD medication, SREBF-1 rs11868035 polymorphism and SREBF-2 rs1052717 polymorphism on the WM microstructure, using tract-based spatial statistics with threshold-free cluster enhancement.

RESULTS

We reported increased FA associated with the risk rs11868035 G/G genotype in several WM tracts, mainly located in the left hemisphere, and opposite effects of the APD medication load, with reduced FA and generally increased diffusivity. These opposite effects overlapped in the forceps minor, cingulum, uncinate fasciculus, the superior and inferior longitudinal fasciculi, the corticospinal tract, inferior fronto-occipital fasciculus and the anterior thalamic radiation.

CONCLUSION

We suggest that changes of WM structure could be an as yet poorly explored biomarker of the effects of APDs, to be further investigated in prospective studies correlating long-term clinical effects with changes of DTI measures in specific WM tracts contributing to the functional integrity of the brain. © 2015 S. Karger AG, Basel.

Lithium and GSK-3β promoter gene variants influence cortical gray matter volumes in bipolar disorder

RATIONALE

Lithium is the mainstay for the treatment of bipolar disorder (BD) and inhibits glycogen synthase kinase-3β (GSK-3β). The less active GSK-3β promoter gene variants have been associated with less detrimental clinical features of BD. GSK-3β gene variants and lithium can influence brain gray and white matter structure in psychiatric conditions, so we studied their combined effect in BD.

OBJECTIVES

The aim of this study is to investigate the effects of ongoing long-term lithium treatment and GSK-3β promoter rs334558 polymorphism on regional gray matter (GM) volumes of patients with BD.

MATERIALS AND METHODS

GM volumes were estimated with 3.0 Tesla MRI in 150 patients affected by a major depressive episode in course of BD. Duration of lifetime lithium treatment was retrospectively assessed. Analyses were performed by searching for significant effects of lithium and rs334558 in the whole brain.

RESULTS

The less active GSK-3β rs334558*G gene promoter variant and the long-term administration of lithium were synergistically associated with increased GM volumes in the right frontal lobe, in a large cluster encompassing the boundaries of subgenual and orbitofrontal cortex (including Brodmann areas 25, 11, and 47). Effects of lithium on GM revealed in rs334558*G carriers only, consistent with previously reported clinical effects in these genotype groups, and were proportional to the duration of treatment.

CONCLUSIONS

Lithium and rs334558 influenced GM volumes in areas critical for the generation and control of affect, which have been widely implicated in the process of BD pathophysiology. In the light of the protective effects of lithium on white matter integrity, our results suggest that the clinical effects of lithium associate with a neurotrophic effect on the whole brain, probably mediated by GSK-3β inhibition.

Exploring effects of EAAT polymorphisms on cognitive functions in schizophrenia

AIM

To evaluate the effect of functional polymorphisms (rs4354668 and rs2731880) of the excitatory amino acid transporters (EAAT1 and 2) on the cognitive dysfunction that characterizes schizophrenia.

MATERIALS & METHODS

One hundred and ninety two subjects diagnosed with schizophrenia were assessed with Brief Assessment of Cognition in Schizophrenia, Wisconsin Card Sorting Test, Continuous Performance Test and N-back test and genotyped for rs4354668 and rs2731880.

RESULTS

ANOVA showed a significant difference among both EAAT1 and EAAT2 genotype groups on different cognitive measures. Worse performances were observed among carriers of the genotypes associated with lower EAAT expression.

CONCLUSION

RESULTS suggest that impaired activity and EAAT expression could influence cognitive performances in schizophrenia, thus representing a target of interest for development of pharmacological strategies aimed to improve cognition.

COMT Val158Met and 5-HT1A-R -1019 C/G polymorphisms: effects on the negative symptom response to clozapine

Aim: Clozapine is still considered the gold standard for treatment-resistant schizophrenia patients; however, up to 40% of patients do not respond adequately. Identifying potential predictors of clinical response to this last-line antipsychotic could represent an important goal for treatment. Among these, functional polymorphisms involved in dopamine system modulation, known to be disrupted in schizophrenia, may play a role. We examined the COMT Val158Met polymorphism, which plays a key role in dopamine regulation at the prefrontal level, and the 5-HT1A-R -1019 C/G polymorphism, a target of clozapine activity involved in the interaction between the serotonin and dopamine systems. Materials & methods: 107 neuroleptic-refractory, biologically unrelated Italian patients (70 males and 37 females) with a DSM-IV diagnosis of schizophrenia who were being treated with clozapine were recruited. Psychopathology was assessed by the Positive and Negative Symptoms Scale (PANSS) at the beginning of treatment, and at weeks 8 and 12. Genomic DNA was extracted from venous blood samples. COMT rs4680 (Val158Met) and 5-HT1A-R rs6295 (-1019 C/G) polymorphisms were analyzed by PCR-based restriction fragment length and direct sequencing, respectively. Results: We found a significant effect of COMT and 5-HT1A-R on the PANSS Negative Subscale variation, with greater improvement among COMT Val/Val and 5-HT1A-R G/G subjects. Conclusion: The findings support the hypothesis that COMT rs4680 and 5-HT1A-R rs6295 polymorphisms could influence the negative symptom response to clozapine, probably through modulation of the dopaminergic system.

Original submitted 26 February 2014; Revision submitted 15 October 2014

The serotonin transporter genotype modulates the relationship between early stress and adult suicidality in bipolar disorder

OBJECTIVE

Bipolar disorder (BD) is associated with a higher risk of suicide and with worse early life stress. A serotonin (5-hydroxytryptamine; 5-HT) transporter-linked polymorphic region (5-HTTLPR) has been shown to influence the relationship between stress and the risk of attempting suicide in the general population, but has not been investigated in BD.

METHODS

We studied 136 inpatients (93 females, 43 males) with a major depressive episode in the course of BD. Early and recent stressful life events were scored on the Social Readjustment Rating Scale (SRRS). Regional gray matter (GM) volumes were analyzed, acquiring T1-weighted images on a 3.0 Tesla scanner.

RESULTS

Homozygote l/l patients attempted suicide in a higher proportion than *s carriers. A separate-slopes logistic regression showed a significant effect of 5-HTTLPR on the relationship between stress, depression, and suicide among *s carriers, but not among l/l homozygotes, early stress associated with worse probability of attempting suicide and with earlier age at onset of BD. Exposure to early stress correlated with GM volumes in the right prefrontal cortex (Brodmann area 46) - again, in *s carriers only.

CONCLUSIONS

5-HTTLPR modulated the relationship between early life stress and the core features of bipolar illness. 5-HTTLPR*s carriers showed a higher sensitivity to the effects of stress; when exposed to low levels of early stress, they were protected against suicide in respect to l/l, but higher levels of stress progressively increased their risk of suicide and reduced the age at onset of illness.

COMT and STH polymorphisms interaction on cognition in schizophrenia

Catechol-O-methyltransferase (COMT) gene, a key regulator of prefrontal cortex (PFC) dopamine (DA) availability, has been extensively studied in relation to cognitive domains, mainly executive functions, that are impaired in schizophrenia, but results are still controversial. Since recent studies in patients affected by neurodegenerative and psychiatric disorders suggested a role of saitohin (STH) gene as a concurring factor in hypofrontality, we hypothesize that STH and COMT polymorphisms could have an additive effect on cognition in schizophrenia. Three forty three clinically stabilized patients with schizophrenia were assessed with a broad neuropsychological battery including the Brief Assessment of Cognition in Schizophrenia, the Wisconsin Card Sorting Test and the Continuous Performance Test and were genotyped for COMT Val108/158Met and STH Q7R polymorphisms. We observed the effects of COMT on speed of processing and executive functions, as well as a significant effect of STH on executive functions performances. Moreover, a significant interaction between COMT and STH polymorphisms was found on executive functions, with COMT Val/Val and STH R carriers performing worse. Our results showed a significant interaction effect of COMT and STH polymorphisms on cognitive performances, strengthening the involvement of STH in cognitive impairments, especially in the domains commonly impaired in schizophrenia.

Factors affecting cognitive remediation response in schizophrenia: the role of COMT gene and antipsychotic treatment

Cognitive remediation is the best available tool to treat cognitive deficits in schizophrenia and has evidence of biological validity; however results are still heterogeneous and significant predictors are lacking. Previous studies showed that cognitive remediation is able to induce changes in PFC function and dopaminergic transmission and thus the study of possible sources of variability at these levels (i.e. antipsychotic treatments and genetic variability) might help to gain a deeper understanding of neurobiological correlates and translate into optimization and personalization of interventions. In the present study, we analyzed the interaction between pharmacological treatment (clozapine vs typical/atypical D2 blockers) and COMT rs4680 polymorphism on cognitive changes after cognitive remediation therapy, in a sample of 98 clinically stabilized patients with schizophrenia. The General Linear Model showed a significant interaction of pharmacological treatment and COMT polymorphism on the improvement in "Symbol Coding" subtest, a global measure of speed of processing. Post-hoc analysis revealed a significant difference between COMT genotypes, when treated with D2 blockers, with worse results among Val/Val patients. These preliminary results suggest that genetic variability, influencing prefrontal dopamine, might affect individual capacity to improve with different patterns, depending on antipsychotic treatment.

Effect of early stress on hippocampal gray matter is influenced by a functional polymorphism in EAAT2 in bipolar disorder

Current views on the pathogenesis of psychiatric disorders focus on the interplay between genetic and environmental factors, with individual variation in vulnerability and resilience to hazards being part of the multifactorial development of illness. The aim of the study is to investigate the effect of glutamate transporter polymorphism SLC1A2-181A>C and exposure to Adverse Childhood Experiences (ACE) on hippocampal gray matter volume of patients with bipolar disorder (BD). Patients exposed to higher levels of ACE reported lower gray matter volume. The effect of SLC1A2-181A>C revealed itself only among patients exposed to lower levels of ACE, with T/T homozygotes showing the lowest, and G/G the highest, gray matter volume. The greatest difference between high and low exposures to ACE was observed in carriers of the G allele. Since the mutant G allele has been associated with a reduced transcriptional activity and expression of the transporter protein, we could hypothesize that after exposure to highest levels of ACE G/G homozygotes are more vulnerable to stress reporting the highest brain damage as a consequence of an excess of free glutamate.