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Objectives: Glutamatergic transmission and N-methyl-D-aspartate receptors (NMDARs) have been implicated in the pathophysiology schizophrenic spectrum and major depressive disorders. Less is known about the role of NMDARs in bipolar disorder (BD). The present systematic review aimed to investigate the role of NMDARs in BD, along with its possible neurobiological and clinical implications., Methods: We performed a computerized literature research on PubMed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, using the following string: (("Bipolar Disorder"[Mesh]) OR (manic-depressive disorder[Mesh]) OR ("BD") OR ("MDD")) AND ((NMDA [Mesh]) OR (N-methyl-D-aspartate) OR (NMDAR[Mesh]) OR (N-methyl-D-aspartate receptor))., Results: Genetic studies yield conflicting results, and the most studied candidate for an association with BD is the GRIN2B gene. Postmortem expression studies (in situ hybridization and autoradiographic and immunological studies) are also contradictory but suggest a reduced activity of NMDARs in the prefrontal, superior temporal cortex, anterior cingulate cortex, and hippocampus., Conclusions: Glutamatergic transmission and NMDARs do not appear to be primarily involved in the pathophysiology of BD, but they might be linked to the severity and chronicity of the disorder. Disease progression could be associated with a long phase of enhanced glutamatergic transmission, with ensuing excitotoxicity and neuronal damage, resulting into a reduced density of functional NMDARs., (© 2023 The Authors. Bipolar Disorders published by John Wiley & Sons Ltd.)

Background: Psychomotor agitation (PA) or retardation (PR) during major depressive episodes (MDEs) have been associated with depression severity in terms of treatment-resistance and course of illness., Objectives: We investigated the possible association of psychomotor symptoms (PMSs) during a MDE with clinical features belonging to the bipolar spectrum., Methods: The initial sample of 7689 MDE patients was divided into three subgroups based on the presence of PR, PA and non-psychomotor symptom (NPS). Univariate comparisons and multivariate logistic regression models were performed between subgroups., Results: A total of 3720 patients presented PR (48%), 1971 showed PA (26%) and 1998 had NPS (26%). In the PR and PA subgroups, the clinical characteristics related to bipolarity, along with the diagnosis of bipolar disorder (BD), were significantly more frequent than in the NPS subgroup. When comparing PA and PR patients, the former presented higher rates of bipolar spectrum features, such as family history of BD (OR = 1.39, CI = 1.20-1.61), manic/hypomanic switches with antidepressants (OR = 1.28, CI = 1.11-1.48), early onset of first MDE (OR = 1.40, CI = 1.26-1.57), atypical (OR = 1.23, CI = 1.07-1.42) and psychotic features (OR = 2.08, CI = 1.78-2.44), treatment with mood-stabilizers (OR = 1.39, CI = 1.24-1.55), as well as a BD diagnosis according to both the DSM-IV criteria and the bipolar specifier criteria. When logistic regression model was performed, the clinical features that significantly differentiated PA from PR were early onset of first MDE, atypical and psychotic features, treatment with mood-stabilizers and a BD diagnosis according to the bipolar specifier criteria., Conclusions: Psychomotor symptoms could be considered as markers of bipolarity, illness severity, and treatment complexity, particularly if PA is present., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objectives: The Bipolar Disorders: Improving Diagnosis, Guidance and Education (BRIDGE)-II-Mix study aimed to estimate the frequency of mixed states in patients with a major depressive episode (MDE) according to different definitions. The present post-hoc analysis evaluated the association between obesity and the presence of mixed features and bipolarity., Methods: A total of 2811 MDE subjects were enrolled in a multicenter cross-sectional study. In 2744 patients, the body mass index (BMI) was evaluated. Psychiatric symptoms, and sociodemographic and clinical variables were collected, comparing the characteristics of MDE patients with (MDE-OB) and without (MDE-NOB) obesity., Results: Obesity (BMI ≥30) was registered in 493 patients (18%). In the MDE-OB group, 90 patients (20%) fulfilled the DSM-IV-TR criteria for bipolar disease (BD), 225 patients (50%) fulfilled the bipolarity specifier criteria, 59 patients (13%) fulfilled DSM-5 criteria for MDEs with mixed features, and 226 patients (50%) fulfilled Research-Based Diagnostic Criteria for an MDE. Older age, history of (hypo)manic switches during antidepressant treatment, the occurrence of three or more MDEs, atypical depressive features, antipsychotic treatment, female gender, depressive mixed state according to DSM-5 criteria, comorbid eating disorders, and anxiety disorders were significantly associated with the MDE-OB group. Among (hypo)manic symptoms during the current MDE, psychomotor agitation, distractibility, increased energy, and risky behaviors were the variables most frequently associated with MDE-OB group., Conclusions: In our sample, the presence of obesity in patients with an MDE seemed to be associated with higher rates of bipolar spectrum disorders. These findings suggest that obesity in patients with an MDE could be considered as a possible marker of bipolarity., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)