Neurophysiological effects of multiple mood episodes in bipolar disorder

Abstract

Objectives: Bipolar disorder is marked by progressive symptomatic changes, which have been linked with episode-related structural findings-particularly in the prefrontal cortex. However, few studies have examined neurofunctional and neurochemical effects of disease burden. In this study, we compared first-and multi-episode bipolar individuals. We hypothesized that the latter would demonstrate evidence of neurophysiological differences consistent with a model of progressive functional degradation of these networks. Methods:First-and multi-episode manic bipolar subjects participated in functional magnetic resonance imaging (fMRI) including a continuous performance task with emotional distractors, and in single-voxel ( 1 H) magnetic resonance spectroscopy (MRS). A priori fMRI regions-of-interest (ROI) included structures comprising prefrontal-striatal-amygdala networks; ( 1 H)MRS voxels were placed within bilateral ventrolateral prefrontal (VLPFC) and anterior cingulate cortex (ACC). Both ROI and voxel-based brain activation in response to emotional stimuli, and neurochemical concentrations derived from ( 1 H)MRS were compared across bipolar groups.Results: Multi-episode bipolar subjects showed relatively lower regional activation across prefrontal-striatal-amygdala networks, including bilateral VLPFC, orbitofrontal cortex, ACC, putamen, caudate, and amygdala. Exploratory whole-brain, voxel-based analysis suggested additional areas of lower activation extending into Brodmann area 22, posterior parietal regions, and right thalamus. Glutamate and N-acetylaspartate (NAA) concentrations were also relatively lower in the ACC of multi-episode subjects.Conclusions: Disease burden, exemplified by multiple affective episodes is associated with evidence of widespread decrements in affective network activity. Lower ACC NAA concentration is similarly consistent with a model of progressive functional deficits. These findings support the functional significance of previously observed progressive structural changes throughout these regions. K E Y W O R D Sbipolar disorder, fMRI, mania, MRS, neuroprogression

Identifying subtypes of bipolar disorder based on clinical and neurobiological characteristics

“…Furthermore, patients with multiple episodes potentially encounter progressive neuropathological changes when mood episodes relapse 32 , 33 . Previous studies have reported that neuropathological progression includes deactivation of fronto–limbic–striatal regions 34 .…”

Neuroimagen estructural y polaridad predominante en pacientes con trastorno afectivo bipolar tipo I de Antioquia

“…Estudios más recientes que evalúan el efecto de los episodios afectivos recurrentes compararon neuroimágenes funcionales de pacientes en su primer episodio con las de pacientes con múltiples episodios afectivos, y observaron que los pacientes con curso crónico y múltiples descompensaciones presentan menor activación en los tractos prefrontal -estriado -amigdalino y de forma bilateral en los talamos, las cortezas prefrontal ventro lateral, orbitofrontales y cingulada anterior, putamenes, caudados, amígdalas, área 22 de Brodmann y regiones parietales posteriores derecha. Es probable que alteraciones neurofisiológicas asociadas a un mayor número de episodios afectivos lleven a un decremento de la activación de redes neuronales implicadas en la regulación afectiva en pacientes con TAB (47), y a su vez tenga correlación teórica con alteraciones estructurales que pueden variar de acuerdo con la PP.…”

Magnetic Resonance Spectroscopy and Bipolar Disorder: How Feasible Is This Pairing?

“…As mentioned before, this has a direct correlation with the alteration in the kynurenine pathway. However, the specific findings regarding Glx are mixed; although the most common finding is an increase in its concentration, some studies report a decrease, [ 27 ] or no changes at all [ 26 , 28 , 29 ]. This variation may be due to the region studied, to the different subgroups of BD studied, to an undetermined effect of the medication, or to the limited number of patients studied [ 26 ].…”