Increased volume of the amygdala and hippocampus in bipolar patients treated with lithium

Abstract

Previous structural neuroimaging studies of bipolar disorder have reported conflicting findings in limbic structures. Medication heterogeneity of patient samples may have contributed to these inconsistencies. Using structural magnetic resonance imaging we assessed whether lithium treatment was associated with differences in amygdala and hippocampal volumes in a sample of bipolar adults. A total of 49 magnetic resonance imaging scans were collected from patients who were currently treated with or without lithium. Amygdala and hippocampal volumes were analyzed using tensor-based morphometry. Statistical between-group comparisons of deformation maps showed that patients treated with lithium exhibited significantly increased volumes of the amygdala and hippocampus compared with patients who were not taking lithium. Our findings may help to explain previous inconsistencies in the bipolar literature.

Smaller hippocampal volumes in patients with bipolar disorder are masked by exposure to lithium: a meta-analysis

“…Among these, 17 nonoverlapping studies provided details about exposure to Li. [19][20][21][22][23][26][27][28][29][30][31][32]47,48,[54][55][56] All but 1 of these studies were included in the meta-analysis. The study by Altshuler and colleagues 19 could not be included as it was the only study of Li-treated patients versus controls that provided results for total hippocampal volumes only.…”

“…22,26,[30][31][32]47,48 With the exception of the study by Foland and colleagues, 47 the other studies were described in the previous comparisons.…”

“…Three of 7 studies reported separate estimates of the duration of illness and number of episodes, which were comparable between the Li and non-Li groups. 26,47,48 A single study separated the episodes into manic and depressive for the Li-treated and the non-Li groups 47 ( Table 1). No study used the duration of illness or the number of episodes as inclusion criteria.…”

“…7 Lithiumexposed patients in retrospective studies have typically shown larger hippocampal volumes than unmedicated participants. 26,47,48 Thus, it is possible that hippocampal volume changes in patients with bipolar disorder are masked by exposure to putative neuroprotective effects of Li. 1,2 In this study we investigated whether there is an association between hippocampal volumes and Li treatment and whether the absence of hippocampal volume differences between patients with bipolar disorder and controls in most available studies was related to the inclusion of Li-treated participants.…”

Emotional and Motivational Processes in Bipolar Disorder: A Neural Network Perspective

“…Mood-stabilizers, such as lithium, were shown to increase the gray matter volume of the amygdala, hippocampus, and anterior cingulate cortex in bipolar disorder [116,[145][146][147][148][149]. In contrast, antipsychotics and anticonvulsants do not seem to influence gray matter volume of structures involved in emotional and motivational processes [150].…”