The NEO-FFI domain of openness to experience moderates ketamine response in treatment resistant depression.

BACKGROUND: There are many putative mechanisms by which ketamine has its effect and many unanswered questions about risks and benefits of long-term ketamine therapy. A research imperative is the identification of predictors of response to intravenous ketamine, especially a sustained response to maintenance ketamine. Temperament is an inherited aspect of personality and is a predictive factor for outcome in treatment resistant depressed (TRD) patients. METHODS: We analyzed which domains of personality impacted initial and sustained ketamine response. Utilizing the Neuroticism Extraversion Openness Five Factor Inventory (NEO-FFI) on 125 participants with TRD, we tested (1) whether the degree of neuroticism predicted initial and/or sustained response to ketamine; and (2) whether extraversion, agreeableness, openness to experience, and conscientiousness had an impact on response. RESULTS: Our findings confirmed previous literature that elevated neuroticism, low conscientiousness, and low extraversion was the pattern of our TRD population regardless of response. Openness was the only factor to significantly predict sustained treatment outcome. LIMITATIONS: Our findings are limited by the lack of placebo control, small sample size, non- standardized infusion intervals, polypharmacy rather than ketamine monotherapy, a select TRD population in that they had all failed ECT, and a primarily Caucasian population. CONCLUSIONS: Our registry adds to the literature that factors making up temperament may have predictive value in regard to treatment response, specifically the outcome for TRD patients receiving long-term ketamine infusion therapy. If confirmed, assessing for Openness could reduce inappropriate exposure to ketamine with its attendant unknown long-term risks.

Metabolic Syndrome Rather Than Body Mass Index Is Associated With Treatment Response to Ketamine Infusions.

PURPOSE: There is a practical need for the identification of pretreatment clinical and epidemiological response predictors to repeat ketamine infusions. Response predictors can serve to guide clinical inclusion of patients and weigh risks versus benefits for those receiving maintenance ketamine. Previous studies indicate a link between obesity, depression, and treatment response. We sought to investigate if body mass index (BMI) or metabolic syndrome could predict treatment response to ketamine. METHODS: Patients aged 18 to 72 years who were electroconvulsive therapy nonresponders were given a subanesthetic ketamine hydrochloride dose of 0.5 mg/kg delivered intravenously for 40 minutes for an acute series of 3 to 6 infusions every other day. If patients reported at least a 50% decrease in depression symptoms after the acute series, they were moved to a maintenance series of infusions, on an individualized basis. To assess if BMI or metabolic syndrome could predict response, logistic regression models were run to analyze initial responders, sustained responders, and nonresponders. Models were adjusted for age, sex, and baseline depression severity. RESULTS: Of the 150 patients analyzed, 56 did not respond to the acute phase, 38 initially responded to the acute phase but relapsed during the maintenance phase, and 56 sustained their response for 1 year. In unadjusted models, BMI was not shown to be a predictor of initial or sustained response. Alternatively, metabolic syndrome defined by a diagnosis of hypertension, hyperglycemia, or hyperlipidemia was determined to be significantly associated with diminished initial response but not sustained response. CONCLUSIONS: In our patient group, results support the literature that outcome in antidepressant therapy is affected by the presence of metabolic syndrome rather than obesity itself. Although BMI did not predict initial response to ketamine, the presence of metabolic syndrome was significantly negatively associated with the initial response to an acute series of ketamine infusions.

Effects of Repeated Intravenous Ketamine in Treatment-Resistant Geriatric Depression: A Case Series.

PURPOSE: There is an immediate need for more sustainable, effective therapies for treatment-resistant depression in patients who do not respond to traditional psychopharmacology. The aim of this study was to determine the efficacy and safety of intravenous ketamine infusions on the elderly population by using a case series of 6 geriatric patients with treatment-resistant depression. METHODS: Eligible patients aged 65 to 82 were given a subanesthetic ketamine hydrochloride dose of 0.5 mg/kg delivered intravenously over 40 minutes twice weekly for an acute series. If patients reported a 50% decrease in depression symptoms after the acute series of 2 to 4 infusions, they would be moved to a maintenance series of infusions, which would occur every 2 to 6 weeks on an individual basis. RESULTS: Of the 6 patients given ketamine, 1 failed to respond to the acute treatment phase, 4 responded to the acute infusion phase but failed to sustain a response after a range of 8 to 22 maintenance infusions, and 1 responded to the infusions but relapsed into alcohol use; therefore, treatment was discontinued. CONCLUSIONS: The relative safety of intravenous ketamine in the elderly was demonstrated by the mild, transient adverse effects seen by this patient group. The geriatric population is unable to maintain an antidepressant response to intravenous ketamine over time, signifying that ketamine has low efficacy for the elderly.

Sub-threshold bipolar disorder in medication-free young subjects with major depression: Clinical characteristics and antidepressant treatment response.

BACKGROUND: This study, for the first time, compared illness and antidepressant response characteristics of young subjects with major depression (MDD) at low (LRMDD) or high-risk (HRMDD) for developing bipolar disorder with characteristics of young bipolar (BPD) subjects and healthy controls (HC). METHODS: One hundred and six young (15-30 yr), medication-free subjects MDD subjects (HRMDD, N = 51; LRMDD, N = 55) were compared with 32 BPD (Type I: 14; Type II: 18) as well as 49 HC subjects. Baseline illness characteristics and frequency of comorbid conditions were examined using Analysis of Variance and Cochran-Armitage trend test. Additionally, in MDD subjects, the effect of open-label antidepressant treatment for up to 24 months with periodic assessments was compared between HRMDD and LRMDD groups for treatment response, remission and (hypo)mania switch while controlling for attrition. RESULTS: Significant gradation from LRMDD to HRMDD to BPD groups was found for increasing occurrence of alcohol dependence (p = 0.006), comorbid PTSD (p = 0.006), borderline personality traits (p = 0.001), and occurrence of melancholic features (p < 0.005). Antidepressant treatment response was similar between the two groups except that for the 12-month period HRMDD showed a trend for a lower response. Switch to (hypo)mania was infrequent in both groups though the HRMDD showed a higher occurrence of spikes in (hypo)mania symptoms (>25% increase in YMRS scores)(p = 0.04). CONCLUSION: Findings of the study indicate that a substantial proportion of young MDD subjects share BPD illness characteristics. These HRMDD subjects, if treated with antidepressants, need to be monitored for development of BPD. TRIAL REGISTRATION: NCT01811147.