Structural and Functional Brain Correlates of Neuroprogression in Bipolar Disorder

Increased grey matter volumes in the temporal lobe and its relationship with cognitive functioning in euthymic patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) is characterized by episodic mood dysregulation, although a significant portion of patients suffer persistent cognitive impairment during euthymia. Previous magnetic resonance imaging (MRI) research suggests BD patients may have accelerated brain aging, observed as lower grey matter volumes. How these neurostructural alterations are related to the cognitive profile of BD is unclear.

METHODS

We aim to explore this relationship in euthymic BD patients with multimodal structural neuroimaging. A sample of 27 euthymic BD patients and 24 healthy controls (HC) underwent structural grey matter MRI and diffusion-weighted imaging (DWI). BD patient's cognition was also assessed. FreeSurfer algorithms were used to obtain estimations of regional grey matter volumes. White matter pathways were reconstructed using TRACULA, and four diffusion metrics were extracted. ANCOVA models were performed to compare BD patients and HC values of regional grey matter volume and diffusion metrics. Global brain measures were also compared. Bivariate Pearson correlations were explored between significant brain results and five cognitive domains.

RESULTS

Euthymic BD patients showed higher ventricular volume (F(1, 46) = 6.04; p = 0.018) and regional grey matter volumes in the left fusiform (F(1, 46) = 15.03; pFDR = 0.015) and bilateral parahippocampal gyri compared to HC (L: F(1, 46) = 12.79, pFDR = 0.025/ R: F(1, 46) = 15.25, pFDR = 0.015). Higher grey matter volumes were correlated with greater executive function (r = 0.53, p = 0.008).

LIMITATIONS

We evaluated a modest sample size with concurrent pharmacological treatment.

CONCLUSIONS

Higher medial temporal volumes in euthymic BD patients may be a potential signature of brain resilience and cognitive adaptation to a putative illness neuroprogression. This knowledge should be integrated into further efforts to implement imaging into BD clinical management.

Brain atrophy and cognitive decline in bipolar disorder: Influence of medication use, symptomatology and illness duration

Bipolar disorder (BPD) is a chronic condition characterized by recurrent episodes of mania and depression. To date, the association of biological and psychopathological processes in BPD has not been extensively studied on a cognitive and cortical basis at the same time. We investigated whether brain atrophy (in prefrontal, temporal and occipital cortices) was associated with cognitive, biological and clinical processes in patients with BPD and healthy controls (HCs). A total of 104 participants (56 with BPD) completed tasks that measured attention, memory, information processing speed, inhibitory control, visuospatial working memory and cognitive flexibility. In addition, structural brain scans were obtained using high-resolution MRI. Outcomes of the measurements were examined using robust multiple mediation analyses. BPD patients showed greater cortical atrophy across all regions of interest when compared to HCs, linked to cognitive decline. BPD patients had slower reaction times and markedly increased errors of commission on the tasks. The outcomes were significantly influenced by medication use, symptomatology and illness duration. The findings showcase the complexity of brain structures and networks as well as the physiological mechanisms underlying diverse BPD symptomatology and endophenotypes. These differences were pronounced in patients with BPD, motivating further investigations of pathophysiological mechanisms involved in brain atrophy and cognitive decline.

Gray matter abnormalities and associated familial risk endophenotype in individuals with first-episode bipolar disorder: Evidence from whole-brain voxel-wise meta-analysis

Gray matter abnormalities have been widely reported in individuals with and at familial risk for bipolar disorder (BD). However, inconsistent findings were reported, and whether shared abnormalities exist between at-risk individuals and patients which can represent an endophenotype remained unclear. This meta-analysis aimed at identifying robust patterns of gray matter changes in patients with first-episode BD (FEBD) and associated risk endophenotype of BD. A systematic literature search was performed to identify eligible voxel-based morphometry studies comparing FEBD patients and healthy controls. Findings of included studies were integrated using the Seed-based d Mapping toolbox. Common and distinct patterns of gray matter abnormalities between FEBD patients and unaffected at-risk individuals were explored. A total of 16 VBM studies comparing 411 FEBD patients and 521 controls were included. FEBD patients showed increased gray matter volume in the cerebellum, posterior cingulate cortex and striatum, and decreased gray matter volume in the medial superior frontal gyrus and gyrus rectus. No common abnormalities were identified between FEBD patients and unaffected at-risk individuals. More gray matter loss in the medial superior frontal gyrus and insula were found in FEBD patients relative to unaffected at-risk individuals. These findings revealed robust gray matter abnormalities in the cortico-striato-cerebellar and default mode network regions in FEBD, and implicated that gray matter deficits may not represent a familial risk endophenotype of BD.

COVID-19 and first manic episodes: a systematic review

Sars-CoV-2 is a respiratory virus that can access the central nervous system, as indicated by the presence of the virus in patients' cerebrospinal fluid and the occurrence of several neurological syndromes during and after COVID-19. Growing evidence indicates that Sars-CoV-2 can also trigger the acute onset of mood disorders or psychotic symptoms. COVID-19-related first episodes of mania, in subjects with no known history of bipolar disorder, have never been systematically analyzed. Thus, the present study assesses a potential link between the two conditions. This systematic review analyzes cases of first appearance of manic episodes associated with COVID-19. Clinical features, pharmacological therapies, and relationships with pre-existing medical conditions are also appraised. Medical records of twenty-three patients fulfilling the current DSM-5 criteria for manic episode were included. Manic episodes started, on average, after 12.71±6.65 days from the infection onset. Psychotic symptoms were frequently reported. 82.61% of patients exhibited delusions, whereas 39.13% of patients presented hallucinations. A large discrepancy in the diagnostic workups was observed. Mania represents an underestimated clinical presentation of COVID-19. Further studies should focus on the pathophysiological substrates of COVID-19-related mania and pursue appropriate and specific diagnostic and therapeutic workups.

Bipolar disorder treatment according to illness trajectory: a systematic review of clinical trials

The current bipolar disorder treatment guidelines focus mainly on the prevention of recurrence and stabilization of acute mood episodes while neglecting outcomes related to the longitudinal course of illness. We systematically reviewed studies that assess the impact of disease progression in the treatment of patients with bipolar disorder. We searched PubMed, Embase, and Web of Science for clinical trials that moderated treatment effects by number of previous episodes, disease length, or a clinical staging model. We retrieved 6,156 potential abstracts. After deduplication, 5,376 were screened and eight studies met inclusion criteria. Seven trials moderated results by number of prior episodes, and one of those also used a measure of disease length. One trial used a clinical staging model and yielded informing results. Only three studies evaluated pharmacological interventions, the other five assessing psychotherapeutic modalities. Most of the studies were post-hoc analysis of clinical trials not primarily aimed at studying variables associated with illness trajectory. Overall, a loss of efficacy was found according to clinical progression, which supports early intervention. Tailored recommendations according to disease stages cannot be made. Furthermore, we identified methodological weaknesses and strengths in this subfield of research, suggesting the use of clinical staging models for future studies.

Neuroprogression as an Illness Trajectory in Bipolar Disorder: A Selective Review of the Current Literature

Bipolar disorder (BD) is a chronic and disabling psychiatric condition that is linked to significant disability and psychosocial impairment. Although current neuropsychological, molecular, and neuroimaging evidence support the existence of neuroprogression and its effects on the course and outcome of this condition, whether and to what extent neuroprogressive changes may impact the illness trajectory is still poorly understood. Thus, this selective review was aimed toward comprehensively and critically investigating the link between BD and neurodegeneration based on the currently available evidence. According to the most relevant findings of the present review, most of the existing neuropsychological, neuroimaging, and molecular evidence demonstrates the existence of neuroprogression, at least in a subgroup of BD patients. These studies mainly focused on the most relevant effects of neuroprogression on the course and outcome of BD. The main implications of this assumption are discussed in light of specific shortcomings/limitations, such as the inability to carry out a meta-analysis, the inclusion of studies with small sample sizes, retrospective study designs, and different longitudinal investigations at various time points.

Biological Pathways Associated with Neuroprogression in Bipolar Disorder

There is evidence suggesting clinical progression in a subset of patients with bipolar disorder (BD). This progression is associated with worse clinical outcomes and biological changes. Molecular pathways and biological markers of clinical progression have been identified and may explain the progressive changes associated with this disorder. The biological basis for clinical progression in BD is called neuroprogression. We propose that the following intertwined pathways provide the biological basis of neuroprogression: inflammation, oxidative stress, impaired calcium signaling, endoplasmic reticulum and mitochondrial dysfunction, and impaired neuroplasticity and cellular resilience. The nonlinear interaction of these pathways may worsen clinical outcomes, cognition, and functioning. Understanding neuroprogression in BD is crucial for identifying novel therapeutic targets, preventing illness progression, and ultimately promoting better outcomes.

Environmental Risk Factors for Bipolar Disorders and High-Risk States in Adolescence: A Systematic Review

Background and objectives: A deeper comprehension of the role that environmental risk factors play in the development of adolescent Bipolar Disorder (BD), as well as in the evolution of high-risk states for BD, may entangle further prevention and treatment advances. The present systematic review is aimed at critically summarizing evidence about the role that environmental risk factors play in the development of BD in adolescence and their interaction with BD high-risk states. Materials and Methods: MEDLINE/Pubmed, Scopus and Web of Science datasets were systematically searched until 4 September 2020. Original studies that reported information about the role of environmental risk factors in the development of BD during adolescence, or assessing their influence on the development of psychopathology in high-risk states for BD, were considered for inclusion. Two blind researchers performed title/abstract, full-text screening, and hand-screening of relevant references. The risk of bias was assessed by means of the Newcastle-Ottawa Scale. Results: Fourteen studies were included in the review. Negative stressful life events, particularly sexual and physical abuse, but also emotional mistreatment, were associated with more severe psychopathology in adolescents with BD, as well as with higher risk for developing mood disorders in BD offspring. Similar findings were detected for familial environment-related features, such as parental rejection and low perceived care, while no univocal results were found when analyzing familial functioning. Conclusions: The present systematic review confirmed the relevant role that environmental risk factors, particularly negative stressful live events and family-related features, play in the development of BD psychopathology during adolescence. Future studies are expected to clarify possible further environmental factors that may be implicated in the development of BD during youth that may serve as target of prevention and early treatment strategies.