Department of Psychiatry, Bellvitge University Hospital-IDIBELL, and CIBERSAM, Barcelona-Spain

Author Of 2 Presentations

Neuropsychology and Cognition Poster Presentation

P0811 - Higher hippocampal functional connectivity in preclinical and initial stages of multiple sclerosis (ID 1724)

Abstract

Background

Memory impairment affects more than 50% of patients with multiple sclerosis (MS), strongly impacting their life quality. Previous studies have suggested a correlation between functional hippocampal alterations and episodic memory impairments in MS. Nevertheless, these studies are rarely focused on preclinical nor initial stages of the disease, essential to develop targeted interventions to prevent or delay memory impairment in MS.

Objectives

To investigate episodic memory performance and hippocampal functional connectivity abnormalities in the preclinical and initial stages of MS.

Methods

Cross-sectional study of 50 subjects: 30 healthy controls and 20 patients with clinical and radiological isolated syndrome (CIS/RIS) (n=13 and 7, respectively). Episodic memory capabilities were assessed with a modified version of Rey Auditory Verbal Learning Test (RAVLTm): introduction of two recognition trials in the five learning trials. Moreover, participants underwent a magnetic resonance imaging session on which resting-state sequences were acquired. Regression models were used to evaluate between-group differences in memory capabilities. Two-sample t-tests models were used to assess whole-brain differences in the seed-based functional connectivity (FC) of the bilateral hippocampus. All analysis were controlled for gender, age, educational level and presence of anxiety and/or depressive symptoms.

Results

No between-group differences emerged in the sum of the words of the learning trials (p=0.164), the delayed recall trial (p=0.193) nor the three recognition trials as measured by discriminability index (d’) (p=0.775, p=0.954, p=0.395, respectively) and Criterion Level (C) (p=0.860, p=0.864, p=0.858, respectively). Nevertheless, compared to controls, CIS/RIS showed higher FC in the hippocampi-right angular gyrus network (t= 5.18, p<0.001).

Conclusions

Prior any sign of episodic memory dysfunction in preclinical and initial stages of MS, higher FC in the hippocampi-right angular gyrus are detected. These findings could be explained as compensatory mechanism used by CIS/RIS to achieve the same performance in episodic memory task as healthy controls. At the same time, such FC increase could be an early sign of future episodic memory problems.

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Neuropsychology and Cognition Poster Presentation

P0812 - Hippocampal resting-state functional connectivity in Multiple Sclerosis subtypes (ID 1733)

Presentation Number
P0812
Presentation Topic
Neuropsychology and Cognition

Abstract

Background

Memory impairment is commonly found in multiple sclerosis (MS), presented in between 40 to 75% of patients. It is accepted that hippocampus plays a critical role in memory function therefore studying this brain structure is crucial to understand the nature of memory deficits. However, there is a lack of knowledge regarding how functional connectivity changes in memory-related brain regions, such as the hippocampus, exist between MS subtypes.

Objectives

To investigate hippocampal resting-state functional connectivity changes between MS subtypes and healthy controls, and associations with the presence of total white matter (WM) lesions.

Methods

30 healthy controls and 78 MS patients (34 relapsing-remitting (RRMS)), 24 primary or secondary progressive subtypes (PMS) and 20 clinical or radiological isolated syndrome (CIS/RIS)) underwent a magnetic resonance imaging session. Univariate ANOVA models in SPM12 were used to assess whole-brain differences in the seed-based functional connectivity (FC) of the bilateral hippocampus, between controls and MS subtypes. Regression models then assessed whether the FC strength in the identified hippocampal networks showed a significant association with total WM lesions.

Results

Mean total WM lesion volume was different among MS subtypes (F=18.493; p<0.001), with PMS showing the highest lesioned volume (16.32±14.09ml), followed by RRMS (8.93±9.46ml) and CIS/RIS (2.07±2.67ml). Compared to controls, both the PMS and RRMS showed lower FC in the hippocampi-right middle frontal gyrus network, while RRMS additionally showed lower FC with the rostral anterior cingulate cortex. Conversely, CIS/RIS showed higher FC in the hippocampi-right angular gyrus network. The lower FC in the hippocampi-right middle frontal gyrus network in PMS and RRMS was also significant compared with CIS/RIS, with PMS additionally showing lower FC in the hippocampi-dorsomedial frontal cortex. Finally, RRMS showed lower FC in the hippocampi-left insula network when directly compared to PMS. The strength of FC in the hippocampi-dorsomedial prefrontal cortex network was negatively associated with the total WM lesion volume (R2= 0.085, F= 6.76, p= 0.011) across the MS patients.

Conclusions

Hippocampal FC differences exist depending on MS subtypes, and the highest presence of total WM lesions impacts the FC with medial prefrontal cortex regions. Future studies are necessary to link such hippocampal changes with specific memory impairment.

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