HPA Axis in Major Depression: Cortisol, Clinical
Symptomatology, and Genetic Variation Predict Cognition
Jennifer Keller, Ph.D.
1
, Rowena Gomez, Ph.D.
1,2
, Gordon Williams, M.D.
3
, Anna Lembke,
M.D.
1
, Laura Lazzeroni, Ph.D., Greer M. Murphy Jr, M.D., Ph.D.
1
, and Alan F. Schatzberg,
M.D.
1
1
Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine
2
Palo Alto University
3
Harvard Medical School and Brigham & Women's Hospital
Abstract
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 psychosis (PMD) and without
psychosis (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 (minercorticoid receptor – MR) that encode for glucocorticoid and
mineralcorticoid receptors, 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 healthy controls. GR and MR genetic variation predicted unique
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Corresponding author: Jennifer Keller, Ph.D., Stanford University School of Medicine, Department of Psychiatry and Behavioral
Sciences, 401 Quarry Road, Stanford, CA 94305-5723, Phone: (650) 724-0070, Fax: 650-723-6811, jkeller@stanford.edu.
Conflict of Interest
: Although there is not a conflict of interest, there may appear to be one with Dr. Schatzberg. He has a significant
interest in Corcept Therapeutics, Inc., which licensed the use patent for mifepristone in psychotic major depression. Some of the data
presented here were part of a larger study examining the effectiveness of mifepristone in psychotic major depression. No data on
mifepristone's effectiveness are presented in the submitted report.
Several authors have been named on a use patent related to the SNPs reported in this manuscript, including Alan Schatzberg, Greer
Murphy, and Jennifer Keller.
Dr. Greer Murphy has been a consultant for Brain Resource, Ltd.
HHS Public Access
Author manuscript
Mol Psychiatry
. Author manuscript; available in PMC 2017 March 24.
Published in final edited form as:
Mol Psychiatry
. 2017 April ; 22(4): 527–536. doi:10.1038/mp.2016.120.
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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.
Keywords
Major depression; psychosis; cortisol; glucocorticoid genes; HPA axis; cognition
Introduction
The stress responsive hypothalamic pituitary adrenal (HPA) axis has been implicated in the
pathophysiology of anxiety and depression as well as cognitive functioning. The axis
consists of stimulating forward and feedback inhibition loops involving the brain, pituitary,
and adrenal glands, which regulates glucocorticoid production. Cortisol released from the
adrenal glands, binds in brain with high affinity to mineralocorticoid receptors (MRs) and
with lower affinity to glucocorticoid receptors (GRs). GR is distributed widely throughout
the primate brain, whereas MR is heavily localized to the hippocampus (1). In addition,
glucorticoid responsive elements are found in the regulatory regions of many genes in brain.
Cortisol exerts its tonic influences predominantly via hippocampal MR, whereas feedback
actions at the level of the pituitary and activated brain areas such as the amygdala are
mediated by GR (2, 3). The development of major depression has been postulated to reflect
a dysregulation of MR and/or GR within the hypothalamic-pituitary-adrenocortical system
(4, 5).
Upwards of 40-60% of depressed patients experience hypercortisolemia (6) or other
disturbances of the HPA system, such as flattened circadian state rhythm (7), or an earlier (8)
or elevated nadir (9). However, we and others have found elevated HPA activity is more
closely associated with specific depression subtypes, such as psychotic features (PMD).
PMD patients demonstrate elevated activity of the HPA axis as compared with nonpsychotic
depressives (NPMD) or healthy controls (HC) (10-13). PMD patients have significantly
elevated evening (11) and afternoon (1-4 pm) (10) serum cortisol levels. Furthermore, PMD
patients demonstrate a blunted response to fludrocortisone, a mixed mineralocorticoid/
glucocorticoid agonist (12, 14), high rates of non-suppression on challenge with
dexamethasone, with particularly high post-dexamethasone cortisol levels (13).
Disrupted cognition is also a feature of depression with the most consistent deficits being in
memory and executive function (15). PMD patients have even greater decrements in
cognition than do NPMDs (16). Furthermore, higher cortisol levels have been associated
with impaired cognitive functioning in both healthy controls and depressed patients (16, 17).
The relative roles of GR and MR in cognitive dysfunction in depression have been a focus of
limited study, although, animal data have long pointed to a role for MR in both cortisol
secretion and memory and executive function performance (18). In HCs, blocking MR
impairs memory and executive function (19). In contrast, fludrocortisone decreases cortisol
in healthy controls and depressives and enhances verbal memory (20); significant
correlations between cortisol inhibition and verbal memory (list learning) performance were
observed. MR stimulation with fludrocortisone inhibits cortisol secretion (21), but
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fludrocortisone inhibition of cortisol is attenuated in patients with PMD suggesting impaired
MR function in those patients (12). Last, there is evidence for decreased MR expression in
the hippocampus and prefrontal cortex in depressed patients (22, 23).
Although mineralocorticoid receptors (MR) mediate neuronal changes required for learning
and memory,
NR3C2
(MR) genetic variation thus far has not been associated with specific
aspects of cognition.
NR3C2
genetic variation has been associated with higher serum levels
of brain derived neurotrophic factor (sBDNF), where those with intermediate and high
exposure to physical neglect showed higher sBDNF levels but only in those with the CC
genotype (24). While APOE gene is confirmed as a high risk of Alzheimer's Disease (AD),
Sun and colleagues (25)examined four large datasets, looking for other potential risk genes.
They concluded that one of 10 potential risk genes was
NR3C2
(MR). Since MR is densely
distributed in the hippocampal region (26) and involved in hemodynamic centers in brain
(27), it may be involved in the progression of AD inresponse to stressful stimuli (28).
Recent studies on specific single nucleotide polymorphisms (SNP's) for GR indicate that
some are associated with altered GR sensitivity (29), and in conjunction with COMT genetic
variation are associated with poorer working memory in healthy controls (30). In addition,
Young's group reported that the GR antagonist mifepristone significantly improves visual
memory in bipolar depression (31). Our group has recently reported that GR (but not MR)
genetic variation accounted for a significant amount of variance in mean cortisol levels and
severity of psychosis (32). However, the relationship of variation in NR3C1 that encodes for
GR gene and the directionality of influence on cognition in depression is not yet known.
We have reported previously on potential relationships of cortisol and cognition in limited
samples of subjects (16), but neither we nor others have explored the relationships among
genetic variation, clinical symptoms, and cognition. The specific aim of this project was to
extend on previous findings on cortisol dysregulation to cognitive performance by exploring
whether HPA axis genetic variation (see Table 1 for list of SNPs) also contributes to specific
cognitive performance beyond that predicted by cortisol or clinical measures.
Methods
Participants
Psychiatric participants were recruited through inpatient and outpatients facilities at Stanford
University or self-referred from online and print study advertisements. Fifty-nine patients
with psychotic major depression (PMD) and 58 patients with nonpsychotic major depression
(NPMD) participated in two waves of a larger study on HPA axis in depression.
Depressed patients were required to have a minimum score of 21 on the 21-item Hamilton
Depression Rating Scale (HDRS) and a minimum score of 6 on the Thase Core
Endogenomorphic Scale, with one exception of a PMD who scored 5. These latter two
criteria were designed to ensure inclusion of participants with similar minimum levels of
severity of endogenous-type symptoms. PMDs were also required to have a minimum total
score of 5 on the positive symptom subscale of the Brief Psychotic Rating Scale (BPRS)
which consists of four items: conceptual disorganization, suspiciousness, hallucinations, and
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unusual thought content. A score of 4 on the PSS indicates no positive psychotic symptoms.
NPMD subjects had no history of psychotic symptoms. All patients met the Diagnostic and
Statistical Manual of Mental Disorders (DSM-IV) criteria for a current major depressive
episode, with or without psychotic features.
Healthy control subjects were recruited through online and print study advertisements.
Overall, 63 healthy controls participated in the larger HPA study and 29 provided blood
samples for genetic analyses. Healthy controls (HC) were assessed for Axis I disorders with
the Structured Clinical Interview for DSM-IV. They had a score of less than 6 on the
HDRS-21 and no psychotic symptoms as measured by the BPRS positive symptom
subscale. Furthermore, they had no current or history of Axis I psychiatric illness.
Participants were allowed to remain on their psychiatric medications but were required to
maintain a stable medication dosing regimen for at least 1 week prior to the start of the
study. Depressed patients were taking a combination of antidepressants, antipsychotics,
anxiolytics, and mood stabilizers (see Table 2).
Of the 153 original subjects, various subsets of patients are used in different analyses. See
Supplemental Figure 1 for a consort chart of usable subjects in each aspect of the omnibus
study. Nine patients had unusable or missing neuropsychological assessments, and 15
additional participants were taking estrogens, so the total sample for neuropsychological
analyses is 129. Nine patients had the CVLT-1 instead of the CVLT-II, so those patients were
dropped only from the CVLT analyses. An additional 6 had missing or unusable cortisol
data, and 44 were missing genetic data. Thus, for the genetic analyses the sample was 80
subjects. The sample sizes were based on effect sizes of our previous work on cortisol and
neuropsychological testing results.
Procedure
The study was approved by the Stanford University Institutional Review Board, and all
subjects gave written informed consent before screening. Eligibility screening procedures
included the SCID, HAM-D, BPRS, clinical laboratory tests, comprehensive metabolic
panel, urine drug screening, and urine screening for pregnancy in female subjects. If
participants met inclusion criteria at eligibility screening, they returned for baseline
procedures.
At baseline, participants were re-administered the HAMD-21 and the BPRS to assess for
clinical symptomatology. Participants then were assessed for cognitive function. Overnight
blood sampling then took place on the Stanford Hospital Clinical and Translational Research
Unit. An intravenous line was inserted at 4 PM and blood collected at the top of each hour
for cortisol from 6 pm to 9 am the next day. Sixteen blood samples per patient were
collected. Part way through the first wave of study, collection of blood samples for genetic
analysis began. The majority of available subjects consented to provide blood for genetic
analyses.
Data on subsets of participants have been previously reported. Cortisol and cortisol/cognitive
data were previously reported (11) on a subset of 73 of 129 subjects reported here. Data on
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another subset 78 of 80 subjects who had both cortisol and genetic data were also recently
reported (32). No published paper from this dataset has examined the relationships of
cognition, cortisol, and genetics together.
Cognition
Participants completed a neuropsychological assessment battery that assessed four primary
cognitive domains: attention, working memory, executive function, and verbal memory [see
(16) for full details and Table 3 for a list of tests].
Cortisol Determination
Cortisol assays were conducted by the Brigham Women's Hospital, General Clinical
Research Laboratory in Boston. The analytic sensitivity for cortisol was 0.4 micrograms/dl
with a coefficient of variation of less than 7.9%. Because of the natural diurnal rhythm of the
cortisol slopes, the 15-hour blood collection period was divided into two phases based on the
apparent nadir: the evening level from 1800 to 0100 hours and the morning level from 0100
to 0900 hours. These epochs correspond to the natural descending and ascending slopes of
the cortisol rhythm and are based on the nadir observed in previous studies (11) of
subsamples from this study. Cortisol means were then computed for these two epochs (1800
to 0100 and 0100 to 0900 hrs).
Medication—Patients were taking a variety of psychiatric medications: antidepressants,
anxiolytics, antipsychotics, and/or mood stabilizers. The sample size is not large enough to
subdivide into specific medications; however, because benzodiazepines in particular can
affect cognition (specifically memory) subjects were classified by whether or not they were
regularly taking them, and this variable was entered into the regression model.
Genetics—Blood was collected for assessment of HPA axis genetic markers and herein we
report on three genes:
NR3C1
(Glucocorticoid receptor; GR),
NR3C2
(Mineralcorticoid
Receptor; MR), and FK506 binding protein 5 (FKBP5). Alleles studied were selected using
a standard protocol that utilized 5 specific criteria (see (32) for more details).
DNA was extracted from EDTA-treated whole blood using the Gentra Puregene kit (Qiagen,
Valencia, CA). Genotyping was performed using Taqman real-time PCR (Applied
Biosystems, Foster City, CA). All genotypes were tested for deviation from Hardy Weinberg
equilibrium. SNPs and their frequencies were assayed for each HPA axis gene (32). 27 SNPs
in toto were assessed (see Table 1 for list of SNPs; Supplemental Figures 2 and 3 for linkage
disequilibrium (LD) maps; Supplemental Table 1 for allelic distribution). SNPs that had no
or minimal variability in our sample were excluded from the analysis. If SNPs had fewer
than 4 subjects across all 3 groups homozygous for the rare allele, they were collapsed into
the heterozygous group.
Statistical Analyses
All analyses were conducted using SPSS statistical software. First, ANOVA and Chi Square
analyses were used to examine group differences in demographic variables (age, education,
and gender), as well as clinical ratings (HDRS, BPRS). Next, ANCOVAs were utilized to
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