Faculty Bibliography

BACKGROUND: Previous studies of major depressive disorder (MDD) have focused on abnormalities in the prefrontal cortex and medial temporal regions. There has been little investigation in MDD of midbrain and subcortical regions central to reward/aversion function, such as the ventral tegmental area/substantia nigra (VTA/SN), and medial forebrain bundle (MFB). METHODOLOGY/PRINCIPAL FINDINGS: We investigated the microstructural integrity of this circuitry using diffusion tensor imaging (DTI) in 22 MDD subjects and compared them with 22 matched healthy control subjects. Fractional anisotropy (FA) values were increased in the right VT and reduced in dorsolateral prefrontal white matter in MDD subjects. Follow-up analysis suggested two distinct subgroups of MDD patients, which exhibited non-overlapping abnormalities in reward/aversion circuitry. The MDD subgroup with abnormal FA values in VT exhibited significantly greater trait anxiety than the subgroup with normal FA values in VT, but the subgroups did not differ in levels of anhedonia, sadness, or overall depression severity. CONCLUSIONS/SIGNIFICANCE: These findings suggest that MDD may be associated with abnormal microstructure in brain reward/aversion regions, and that there may be at least two subtypes of microstructural abnormalities which each impact core symptoms of depression.

The low rate of response to antidepressants in treatment resistant depression (TRD) justifies studies of next-step therapies following a treatment failure. In TRD clinical trials, it is important to verify the accurate diagnosis of treatment resistance for all enrolled subjects using a reliable and valid instrument. Self-rated scales can reduce the impact of investigator bias and reduce the time burden for clinical researchers. The Massachusetts General Hospital (MGH) Antidepressant Treatment Response Questionnaire (ATRQ) is a self-rated scale used to determine treatment resistance in major depressive disorder (MDD). The ADAPT-A study is a multi-center double-blind, placebo-controlled study of low-dose aripiprazole adjunctive to ADT among outpatients with TRD. At the screening assessment, potential subjects completed the MGH ATRQ. The ADAPT-A medical monitors subsequently performed remote patient interviews and obtained detailed medication histories. The data obtained from the MGH ATRQ and by the medical monitors were compared for congruency. Of the 186 patients enrolled by the local sites, no subjects deemed treatment resistant by the MGH ATRQ were found to be nonresistant by the medical monitors. In 76.3% (n = 142) of the subjects, the number of failed adequate antidepressant trials reported by the MGH ATRQ was concordant with the data collected by medical monitors. In 16.1% (n = 30) of all cases, the medical monitors found a greater number of failed trials; in 7.5% (n = 14) of cases, the medical monitors found fewer failed medication trials. The discrepancy was by more than one medication trial in only 4.0% (n = 7) of cases. We found the MGH ATRQ to be relatively concordant in its assessment of treatment resistance in depression compared with independent clinical researchers. Although the MGH ATRQ tended to underreport the number of unsuccessful treatment trials relative to the clinical interviews, its accuracy in cases it detected was confirmed by raters.

OBJECTIVE: Presymptomatic individuals with the Huntingtin (HTT) CAG expansion mutation that causes Huntington's disease may have higher levels of depressive symptoms than healthy comparison populations. However, the prevalence of HTT CAG repeat expansions among individuals diagnosed with major depressive disorder has not been established. METHOD: This was a case-control genetic association study of HTT CAG allele size in two discovery cohorts of individuals with major depressive disorder and comparison subjects without major depression as well as a replication cohort of individuals with major depression and comparison subjects without major depression. RESULTS: CAG repeat lengths of 36 or greater were observed in six of 3,054 chromosomes from individuals with major depression, compared with none of 4,155 chromosomes from comparison subjects. In a third cohort, one expanded allele was observed among 1,202 chromosomes in the major depression group, compared with none of 2,678 chromosomes in comparison subjects. No clear pattern of clinical features was shared among individuals with the expanded repeats. CONCLUSIONS: In clinical populations of individuals diagnosed with major depression, approximately 3 in 1,000 carried expanded HTT CAG alleles.

Evidence suggests that mitochondria undergo functional and morphological changes with age. This study aimed to investigate the relationship of brain energy metabolism to healthy aging by assessing tissue specific differences in metabolites observable by phosphorus ((31)P) MRS. (31)P MRSI at 4 Tesla (T) was performed on 34 volunteers, aged 21-84, screened to exclude serious medical and psychiatric diagnoses. Linear mixed effects models were used to analyze the effects of age on phosphorus metabolite concentrations, intracellular magnesium and pH estimates in brain tissue. A significant age associated decrease in brain pH (-0.53% per decade), increase in PCr (1.1% per decade) and decrease in PME (1.7% per decade) were found in total tissue, with PCr effects localized to the gray matter. An increase in beta NTP as a function of age (1% per decade) approached significance (p = 0.052). There were no effects demonstrated with increasing age for intracellular magnesium, PDE or inorganic phosphate. This study reports the effects of healthy aging on brain chemistry in the gray matter versus white matter using (31)P MRS measures of high energy phosphates, pH and membrane metabolism. Increased PCr, increased beta NTP (reflecting ATP) and reduced pH may reflect altered energy production with healthy aging. Unlike some previous studies of aging and brain chemistry, this study examined healthy, non-demented and psychiatrically stable older adults and specifically analyzed gray-white matter differences in brain metabolism.

BACKGROUND: Recent data indicate that lithium use for bipolar disorder has declined over the last decade and that lithium largely has been replaced with alternate, commercially promoted medications that may or may not result in better outcomes. PURPOSE: This article describes the rationale and study design of LiTMUS, a multi-site, prospective, randomized clinical trial of outpatients with bipolar disorder. LiTMUS seeks to address whether initiating therapy at lower doses of lithium as part of optimized treatment (OPT, guideline-informed, evidence-based, and personalized pharmacotherapy) improves outcomes and decreases the need for other medication changes across 6 months of therapy. METHODS: LiTMUS will randomize 284 adults with bipolar disorder (Type I or II) across 6 study sites. The co-primary outcomes are overall illness severity on clinical global improvement scale for bipolar disorder and a novel measure, necessary clinical adjustments. This metric provides a composite that reflects both clinical response and tolerability. Other relevant outcomes include full symptomatic recovery, quality of life, suicidal behaviors, and moderators of suicidality. RESULTS: As of August 28th, 2009, we have consented 338 patients and randomized 281 for this study. LIMITATIONS: The potential limitations of the study include an arbitrary definition of 'low, but effective' doses of lithium, lack of a placebo-controlled group, open treatment, and use of a new outcome measure (i.e., necessary clinical adjustments). CONCLUSION: We expect that this study will inform our understanding of the effectiveness of low to moderate doses of lithium therapy for individuals with bipolar disorder.

OBJECTIVE: To investigate the role of frontal EEG as predictor of clinical response to SSRIs or venlafaxine in major depressive disorder (MDD). METHOD: 82 subjects (age 35.9+/-13.0; 47.6% female) meeting DSM-IV criteria for MDD entered an 8-week prospective treatment with SSRIs or venlafaxine. At baseline and week 1 we recorded serial, 4-channel EEGs (F7-Fpz, F8-Fpz, A1-Fpz, A2-Fpz). We evaluated prospectively the relative theta power as predictor of treatment outcome. We also developed an Antidepressant Treatment Response (ATR) index using EEG parameters assessed at baseline and week 1. RESULTS: 45 subjects (54.9%) responded to treatment (HAM-D-17 reduction>or=50%). At baseline, frontal relative theta power (i.e., 4-8 Hz power/2-20 Hz power) was significantly (p=0.017) lower (21%) in treatment responders than in non-responders (24%). Baseline relative theta power predicted treatment response with 63% accuracy [64% sensitivity, 62% specificity, 66% area under the receiver operator curve (AUROC) (p=0.014)]. Relative theta power at week 1 predicted treatment response with 60% accuracy [62% sensitivity, 57% specificity, 61% AUROC (p=0.089)]. ATR predicted response with 70% accuracy [82% sensitivity, 54% specificity, 72% AUROC (p=0.001)]. CONCLUSION: Using automated analysis of frontal EEG collected during the first week of antidepressant treatment it may be possible to facilitate prediction of SSRI or venlafaxine efficacy in MDD.

We examined the Antidepressant Treatment Response (ATR) index as a predictor of differential response and remission to escitalopram, bupropion, or a combination of the two medications, in subjects with major depressive disorder (MDD). Three hundred seventy-five subjects had a baseline quantitative electroencephalographic (QEEG) study preceding 1 week of treatment with escitalopram, 10 mg, after which a second QEEG was performed and the ATR index was calculated. Subjects then were randomized to continue escitalopram, switch to bupropion, or receive a combination of the two. Clinical response was assessed using the 17-item Hamilton Depression Rating Scale at 49 days of treatment. Accuracy of ATR in predicting response and remission was calculated. There were no significant differences between response and remission rates in the three treatment groups. A single ATR threshold was useful for predicting differential response to either escitalopram or bupropion monotherapy. Subjects with ATR values above the threshold were more than 2.4 times as likely to respond to escitalopram as those with low ATR values (68% vs. 28%). Subjects with ATR values below the threshold who were switched to bupropion treatment were 1.9 times as likely to respond to bupropion alone as those who remained on escitalopram treatment (53% vs. 28%). The ATR index did not provide a useful prediction of response to combination treatment. The ATR index may prove useful in predicting responsiveness to different antidepressant medications.