Hippocampal volume and verbal memory performance in late-stage bipolar disorder

Abstract

Studies about changes in hippocampal volumes in subjects with bipolar disorder (BD) have been contradictory. Since the number of manic episodes and hospitalization has been associated with brain changes and poor cognitive outcomes among BD patients, we have hypothesized that these variables could clarify this issue. We stratified subjects with BD in early (BD-Early), intermediate (BD-intermediate) and late (BD-Late) stages as a function of number of manic episodes and prior hospitalization. Then, we compared their hippocampal volumes and California Verbal Learning Test-II (CVLT-II) scores with healthy controls (HC) using the general linear model. A total of 173 subjects were included in the study (112 HC, 15 BD-Early, 30 BD-Intermediate, and 16 BD-Late). We found a significant group effect on hippocampus volume (F(3,167) = 3.227, p = 0.024). Post-hoc analysis showed that BD-Late subjects had smaller hippocampus than HC (p = 0.017). BD-Early and BD-Intermediate subjects showed no significant difference in hippocampus volume compared to HC and BD-Late subjects. The CVLT trial 1 to 5 scores were significantly different across the groups (F(3,167) = 6.371, p < 0.001). Post-hoc analysis showed that BD-Intermediate (p = 0.006) and BD-Late (p = 0.017) subjects had worse memory performance during immediate recall than HC, while the performance difference between BD-Early subjects and HC was not significant (p = 0.208). These findings add to the notion that BD is a neuroprogressive disorder with brain changes and cognitive impairment according to prior morbidity (number of manic episodes and hospitalization). Also, they suggest that hippocampus is a brain marker and a potential therapeutic target for patients at late stage.

Mood disorders in the elderly: prevalence, functional impact, and management challenges

“…In a recent cross-sectional study in BD type 1, Cao et al67 examined verbal memory and hippocampal volume at late stages of the disease (defined according to the number of manic episodes and hospitalizations); results indicated that memory loss was associated with reduced hippocampal volume in patients with severe forms of BD (ie, ten or more manic episodes and at least one hospitalization due to acute mania or depression), suggesting that hippocampal atrophy may be a late marker of the disease in the brain. Another study by Abé et al68 examined cortical thickness, volume, and surface area in BD patients types I and II; compared to healthy controls, BD patients had lower cortical thickness in several structures, including frontal regions, anterior cingulate cortex, temporal regions, insula, and medial occipital lobe.…”

612. Hippocampal Subfield Volumes in Mood Disorders

“…Based on several studies on the neuroprogression of bipolar disorder and major depressive disorder, the number of episodes was consistent with several aspects of the disorder, such as the brain atrophy and the general functioning. 23,[42][43][44][45][46] The partial correlations were performed between the hippocampal subfield volumes and the illness duration, as well as the numbers of manic, hypomanic, mixed and depressive episodes for BD-I, BD-II, and MDD controlling for age, gender, and ICV. Because a significant portion of patients reported more than 30 mood episodes, we considered the numbers of episodes as ordinal variables instead of scale variables in the correlation analysis.…”

“…[19][20][21][22] A recent study, however, reported that patients with BD have reductions in hippocampus according to prior morbidity (number of manic episodes and hospitalization). 23 Regarding MDD, a recent meta-analysis of 32 magnetic resonance imaging (MRI) studies have confirmed the difference in hippocampal volume between patients and controls, but only among patients with MDD whose duration of illness was longer than two years or who had more than one mood episode. 24 These findings point to a progressive reduction of the hippocampus as a function of prior morbidity in mood disorders.…”

577. Lifespan Gyrification Trajectories of Human Brain in Healthy Individuals and Patients with Major Psychiatric Disorders

“…The trajectory of brain cortical gyrification from childhood to old age in human is still unknown. Additionally, it was hypothesized that major psychiatric disorders, such as major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SCZ), are progressive disorders associated with altered development and aging [6][7][8][9][10][11][12][13] . This hypothesis is based on the association of these disorders with higher prevalence and earlier age of onset of age-related medical conditions 14, 15 (e.g.…”