Rowena G. Gomez

Cortisol circadian rhythm alterations in psychotic major depression.

BACKGROUND Increased hypothalamic-pituitary-adrenal axis activity is well described in psychotic depression with an emphasis on 24-hour, urinary free cortisol levels or dexamethasone suppression tests. There are limited data on cortisol levels during specific times of the day. METHODS Patients with depression with (PMD) and without (NPMD) psychosis and healthy control subjects were studied using rating scales of depression and psychosis and measures of HPA activity, including overnight cortisol and adrenocorticotropin levels. We used analysis of variance to determine group differences and regression analyses to assess contributions of specific measures to cortisol levels. RESULTS PMDs had higher cortisol during the evening hours than did NPMDs or control subjects, who did not differ from one another. Regression analyses suggest that depression and the combination of depressive and psychotic symptoms were important contributors to variance in evening cortisol. CONCLUSIONS PMD is associated with increased cortisol levels during the quiescent hours. Enhanced cortisol activity, particularly a higher nadir, was related to depression severity and the interaction of depressive and psychotic symptoms. This increase suggests a defect in the action of the circadian timing system and HPA axis, creating a hormonal milieu similarly seen in early Cushings syndrome and potentially an (im)balance of mineralocorticoid and glucocorticoid receptor activity.

Hippocampal and Amygdalar Volumes in Psychotic and Nonpsychotic Unipolar Depression

OBJECTIVE The limbic system is thought to underlie dysfunctional affective and cognitive processes in individuals with depression. Neuroanatomical studies of subjects with depression have often examined hippocampal and amygdalar structures, since they are two key structures of the limbic system. Research has often but not always found reduced hippocampal volume in patients with major depression. The purpose of the present study was to examine differences in hippocampal and amygdalar volumes in patients with depression subtypes relative to healthy comparison subjects. METHOD Participants were 1) patients with major depression with psychosis, 2) patients with major depression without psychosis, and 3) healthy comparison subjects. To examine hippocampal and amygdalar volumes, all participants underwent structural magnetic resonance imaging (MRI). The authors further examined the effects of clinical and chronicity data on these two brain structures. RESULTS After age, gender, and total brain volume were controlled, depressed patients with psychosis had a significantly smaller mean amygdala volume relative to depressed patients without psychosis and healthy comparison subjects. There were no differences between depressed patients without psychosis and healthy comparison subjects. Correlational analyses suggested that age of depression onset was strongly associated with amygdala volume. No group differences in hippocampal volume were found. CONCLUSIONS There were no differences between depressed patients and healthy comparison subjects in hippocampal volume. However, psychotic but not nonpsychotic depression was associated with reduced amygdala volume. Reduced amygdala volume was not associated with severity of depression or severity of psychosis but was associated with age at onset of depression. Smaller amygdala volume may be a risk factor for later development of psychotic depression. In addition, chronicity of depression and depression subtype might be two important factors associated with hippocampal and amygdalar volumes in depression.

Aberrant Brain Activation During a Working Memory Task in Psychotic Major Depression

OBJECTIVE The authors sought to better understand the neural circuitry associated with working memory deficits in psychotic major depression by examining brain function during an N-back task. METHOD Study subjects were 16 patients with psychotic major depression, 15 patients with nonpsychotic major depression, and 19 healthy comparison subjects. Functional MRI data were collected while participants responded to letter stimuli that were repeated from the previous trial (1-back) or the one before that (2-back). RESULTS Relative to the healthy comparison group, both the psychotic and nonpsychotic major depression groups had significantly greater activation in the right parahippocampal gyrus during the 2-back task, and the psychotic major depression group showed this overactivation during the 1-back task as well. The nonpsychotic major depression group showed significantly lower activation than other groups in the right dorsolateral prefrontal cortex and greater activation than the healthy comparison group in the superior occipital cortex. The psychotic major depression group was unique in showing greater activation than both other groups in the right temporoparietal junction, a cluster that also demonstrated connectivity with activation in the left prefrontal cortex. CONCLUSIONS The psychotic major depression group showed aberrant parahippocampal activation at a lower demand level than observed in nonpsychotic major depression. While the nonpsychotic major depression group showed abnormalities in frontal executive regions, the psychotic major depression group showed abnormalities in temporoparietal regions associated with orienting to unexpected stimuli. Considering the functional connectivity of this cluster with left dorsolateral prefrontal cortex regions, these findings may reflect neural compensation for sensory gating deficits in psychotic major depression.

Effects of major depression diagnosis and cortisol levels on indices of neurocognitive function

Although many studies have examined separately the effects of depression and cortisol on cognition, no study has examined their relative or potentially additive effects. Our study simultaneously investigated the contributions of clinical status [major depression (MD) versus psychiatrically healthy controls (HC)] and cortisol on a hippocampal/mediotemporal mediated verbal memory task (Paragraph Recall) and a prefrontal cortex/cingulate mediated executive functioning task (Stroop). Thirty-seven unmedicated nondelusional MDs and 18 HCs underwent psychiatric ratings, hourly assessments of cortisol activity over 24 h, and neuropsychological assessments. Hierarchical multiple regressions indicated a significant effect of cortisol but not of diagnosis on verbal memory. Greater cortisol levels were related to poorer memory performance independent of group. In contrast, a significant interaction between cortisol and diagnosis was found for a color-word index of response inhibition. This interaction suggests that the detrimental effect of elevated cortisol level on this type of executive functioning exists only in the healthy control group but not in MDs. On an Interference score, another measure of response inhibition, cortisol had a significant independent effect, but neither the effects of diagnosis and the interaction attained full significance. Our study suggests that cortisol has an independent effect on verbal memory. Also, our study produced evidence of an interaction between diagnosis and cortisol on response inhibition.

The mineralocorticoid receptor agonist, fludrocortisone, differentially inhibits pituitary–adrenal activity in humans with psychotic major depression

INTRODUCTION Hypothalamic-pituitary-adrenal (HPA) axis dysregulation has been linked with major depression, particularly psychotic major depression (PMD), with mineralocorticoid receptors (MRs) playing a role in HPA-axis regulation and the pathophysiology of depression. Herein we hypothesize that the MR agonist fludrocortisone differentially inhibits the HPA axis of psychotic major depression subjects (PMDs), non-psychotic major depression subjects (NPMDs), and healthy control subjects (HCs). METHODS Fourteen PMDs, 16 NPMDs, and 19 HCs were admitted to the Stanford University Hospital General Clinical Research Center. Serum cortisol levels were sampled at baseline and every hour from 18:00 to 23:00h, when greatest MR activity is expected, on two consecutive nights. On the second afternoon at 16:00h all subjects were given 0.5mg fludrocortisone. Mean cortisol levels pre- and post-fludrocortisone and percent change in cortisol levels were computed. RESULTS There were no significant group differences for cortisol at baseline: F(2,47)=.19, p=.83. There were significant group differences for post-fludrocortisone cortisol: F(2,47)=5.13, p=.01, which were significantly higher in PMDs compared to HCs (p=.007), but not compared to NPMDs (p=.18). There were no differences between NPMDs and HCs (p=.61). Also, PMDs had a lower percent change from baseline in cortisol levels at 2200h than NPMDs (p=.01) or HCs (p=.009). CONCLUSIONS Individuals with psychotic major depression compared to healthy control subjects have diminished feedback inhibition of the hypothalamic-pituitary-adrenal (HPA) axis in response to the mineralocorticoid receptor agonist fludrocortisone. To our knowledge, this is the first study to examine HPA axis response to MR stimulation in major depression (with and without psychosis), and only the third study to demonstrate that exogenously administered fludrocortisone can down-regulate the HPA axis in humans.

HPA axis in major depression: cortisol, clinical symptomatology and genetic variation predict cognition.

The hypothalamic–pituitary–adrenal (HPA) axis has been implicated in the pathophysiology of a variety of mood and cognitive disorders. Neuroendocrine studies have demonstrated HPA axis overactivity in major depression, a relationship of HPA axis activity to cognitive performance and a potential role of HPA axis genetic variation in cognition. The present study investigated the simultaneous roles HPA axis activity, clinical symptomatology and HPA genetic variation play in cognitive performance. Patients with major depression with psychotic major depression (PMD) and with nonpsychotic major depression (NPMD) and healthy controls (HC) were studied. All participants underwent a diagnostic interview and psychiatric ratings, a comprehensive neuropsychological battery, overnight hourly blood sampling for cortisol and genetic assessment. Cognitive performance differed as a function of depression subtype. Across all subjects, cognitive performance was negatively correlated with higher cortisol, and PMD patients had higher cortisol than did NPMDs and HCs. Cortisol, clinical symptoms and variation in genes, NR3C1 (glucocorticoid receptor; GR) and NR3C2 (mineralocorticoid receptor; MR) that encode for GRs and MRs, predicted cognitive performance. Beyond the effects of cortisol, demographics and clinical symptoms, NR3C1 variation predicted attention and working memory, whereas NR3C2 polymorphisms predicted memory performance. These findings parallel the distribution of GR and MR in primate brain and their putative roles in specific cognitive tasks. HPA axis genetic variation and activity were important predictors of cognition across the entire sample of depressed subjects and HR. GR and MR genetic variation predicted unique cognitive functions, beyond the influence of cortisol and clinical symptoms. GR genetic variation was implicated in attention and working memory, whereas MR was implicated in verbal memory.

Decreased hypothalamic functional connectivity with subgenual cortex in psychotic major depression.

Hypothalamus communication with the rest of the brain and peripheral target tissues is critically important for many physiological and psychological functions. These functions include maintaining neuroendocrine circadian rhythms and managing affective processes. The hypothalamus maintains both direct neural connections within the brain and it also controls a variety of neuroendocrine processes that can influence target tissues throughout the body. Dysregulation of the hypothalamic pituitary adrenal axis and hyperactivity of the subgenual cortex are both frequently observed in depression. However, many details of how the hypothalamus, the hypothalamic pituitary adrenal (HPA) axis, and the subgenual cingulate interact with each other are unknown. We hypothesized that resting-state functional connectivity between the hypothalamus and the subgenual cortex would be associated with altered circadian rhythm in patients with depression and depressive symptoms. We also hypothesized that this would be most apparent in patients that have major depression with psychotic symptoms, who typically have the most robust HPA-axis dysregulation. Resting-state functional magnetic resonance imaging (fMRI) scans were collected to observe low-frequency resting-state functional connectivity patterns of the hypothalamus in 39 healthy participants, 39 patients with major depression, and 22 patients with major depression with psychotic symptoms. Hourly overnight measures of cortisol secretion and multiple measures of psychiatric symptom severity were also collected on all. Strong hypothalamic functional connectivity with the subgenual cortex was observed in healthy participants. This connectivity was significantly reduced in patients with psychotic major depression. Increased cortisol secretion during the circadian nadir and reduced connectivity were both associated with symptom severity. Reduced connectivity and high cortisol secretion during the circadian nadir are both useful for explaining a significant amount of variance in symptom severity that occurs between healthy participants and depressed patients. However, only cortisol secretion was useful for explaining the severity of symptoms within the depressed groups. This study suggests that the communication between the hypothalamus and the subgenual cortex is disrupted in patients with major depression with psychotic features. It also suggests that these disruptions are associated with increased symptom severity and may be a cause or a consequence of cortisol dysregulation.

Insular Cortex Abnormalities in Psychotic Major Depression: Relationship to Gender and Psychotic Symptoms

Recent data suggests that psychotic major depression (PMD) may be a discrete disorder distinguishable from nonpsychotic major depression (NPMD), and that patients with PMD may be more similar to individuals with schizophrenia than individuals with NPMD. The insula is a brain region in which morphometric changes have been associated with psychotic symptom severity in schizophrenia and affective psychosis. It was hypothesized that insular volumes would be reduced in PMD compared to NPMD and controls, and insular volumes would correlate with psychosis but not depression severity. Insular gray matter volumes were measured in PMD and NPMD patients and matched healthy controls using magnetic resonance images and manual morphometry. Clinical measures of illness severity were obtained to determine their relationship with insular volume. Posterior insular volumes were significantly reduced in PMD compared to HC. There were also significant group-by-gender interactions for total, anterior and posterior insular volumes. Using Pearson product-moment correlations, anterior insular volumes did not correlate with depression severity. Left anterior insular volume was significantly correlated with total and positive symptom psychosis severity in the PMD group. Atypical insular morphometry may be related to the inability to distinguish between internally and externally generated sensory inputs characteristic of psychosis.

The relationships of positive and negative symptoms with neuropsychological functioning and their ability to predict verbal memory in psychotic major depression

Neuropsychological functioning, in relation to positive and negative symptoms in psychotic major depression (PMD), has not been as thoroughly studied as it has been in schizophrenia. Thus, the current study investigated the associations between positive and negative symptoms with cognitive functioning, with an emphasis on verbal memory in PMD. Attention, working memory, and the executive functioning domains were analyzed among 49 PMD participants. Positive symptoms did not correlate significantly with any measures of verbal memory but did correlate with one measure of attention, working memory, and executive functioning. Negative symptoms correlated significantly with two California Verbal Learning Test-II (CVLT-II) measures of verbal memory and three measures of executive function. Hierarchical regressions were conducted to determine if negative symptoms could predict verbal memory performance after controlling for depression. Of the two verbal memory measures, negative symptoms significantly explained additional variance for CVLT Recognition, but not for CVLT Trials 1-5 total score. Our results provide some evidence that, consistent with the schizophrenia literature, negative symptoms contributed more to verbal memory deficits in PMD than positive symptoms, regardless of depression severity.

Diagnostic differences in verbal learning strategies and verbal memory in patients with mood disorders and psychotic disorders

A better understanding of verbal learning strategies can offer insight to the difference in verbal memory performance and learning between patients with schizophrenia and schizoaffective disorders, non-psychotic major depression, and psychotic major depression. To date, a comparison of the use of verbal learning strategies and verbal memory performance amongst these specific diagnostic groups has not been investigated. This study examined differences in verbal learning and memory between psychotic major depression (n = 31), nonpsychotic major depression (n = 30), and schizophrenia spectrum disorders (n = 17) disorders. Verbal learning and memory were assessed through the use of the California Verbal Learning Test-II (CVLT-II). Correlations and multiple regression analyses were conducted to analyze differences in verbal learning and memory amongst these groups. There were no significant differences in the use of Semantic Clustering. Diagnostic differences were observed in the use of Serial and Subjective Clustering. The psychotic major depression group utilized Serial Clustering strategy significantly less than the nonpsychotic major depression group. Learning strategies significantly predicted learning and recall. These findings lend support to the hypothesis that learning strategies predict verbal memory performance across diagnostic groups. The present study contains useful information on diagnostic differences in verbal learning and memory, and a framework by which treatment could be tailored to enhance learning specific to these diagnostic groups.