Assessment of Relationship of Ketamine Dose With Magnetic Resonance Spectroscopy of Glx and GABA Responses in Adults With Major Depression: A Randomized Clinical Trial

IMPORTANCE

A single subanesthetic dose of ketamine produces an antidepressant response in patients with major depressive disorder (MDD) within hours, but the mechanism of antidepressant effect is uncertain.

OBJECTIVE

To evaluate whether ketamine dose and brain glutamate and glutamine (Glx) and γ-aminobutyric acid (GABA) level responses to ketamine are related to antidepressant benefit and adverse effects.

DESIGN, SETTING, AND PARTICIPANTS

This randomized, parallel-group, triple-masked clinical trial included 38 physically healthy, psychotropic medication-free adult outpatients who were in a major depressive episode of MDD but not actively suicidal. The trial was conducted at Columbia University Medical Center. Data were collected from February 2012 to May 2015. Data analysis was conducted from January to March 2020.

INTERVENTION

Participants received 1 dose of placebo or ketamine (0.1, 0.2, 0.3, 0.4, or 0.5 mg/kg) intravenously during 40 minutes of a proton magnetic resonance spectroscopy scan that measured ventro-medial prefrontal cortex Glx and GABA levels in 13-minute data frames.

MAIN OUTCOMES AND MEASURES

Clinical improvement was measured using a 22-item version of the Hamilton Depression Rating Scale (HDRS-22) 24 hours after ketamine was administered. Ketamine and metabolite blood levels were measured after the scan.

RESULTS

A total of 38 individuals participated in the study, with a mean (SD) age of 38.6 (11.2) years, 23 (60.5%) women, and 25 (65.8%) White patients. Improvement in HDRS-22 score at 24 hours correlated positively with ketamine dose (t36 = 2.81; P = .008; slope estimate, 19.80 [95% CI, 5.49 to 34.11]) and blood level (t36 = 2.25; P = .03; slope estimate, 0.070 [95% CI, 0.007 to 0.133]). The lower the Glx response, the better the antidepressant response (t33 = -2.400; P = .02; slope estimate, -9.85 [95% CI, -18.2 to -1.50]). Although GABA levels correlated with Glx (t33 = 8.117; P < .001; slope estimate, 0.510 [95% CI, 0.382 to 0.638]), GABA response did not correlate with antidepressant effect. When both ketamine dose and Glx response were included in a mediation analysis model, ketamine dose was no longer associated with antidepressant effect, indicating that Glx response mediated the relationship. Adverse effects were related to blood levels in men only (t5 = 2.606; P = .048; estimated slope, 0.093 [95% CI, 0.001 to 0.186]), but Glx and GABA response were not related to adverse effects.

CONCLUSIONS AND RELEVANCE

In this study, intravenous ketamine dose and blood levels correlated positively with antidepressant response. The Glx response correlated inversely with ketamine dose and with antidepressant effect. Future studies are needed to determine whether the relationship between Glx level and antidepressant effect is due to glutamate or glutamine.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01558063.

Sex-specific neurobiological actions of prophylactic (R,S)-ketamine, (2R,6R)-hydroxynorketamine, and (2S,6S)-hydroxynorketamine

Enhancing stress resilience in at-risk populations could significantly reduce the incidence of stress-related psychiatric disorders. We have previously reported that the administration of (R,S)-ketamine prevents stress-induced depressive-like behavior in male mice, perhaps by altering α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated transmission in hippocampal CA3. However, it is still unknown whether metabolites of (R,S)-ketamine can be prophylactic in both sexes. We administered (R,S)-ketamine or its metabolites (2R,6R)-hydroxynorketamine ((2R,6R)-HNK) and (2S,6S)-hydroxynorketamine ((2S,6S)-HNK) at various doses 1 week before one of a number of stressors in male and female 129S6/SvEv mice. Patch clamp electrophysiology was used to determine the effect of prophylactic drug administration on glutamatergic activity in CA3. To examine the interaction between ovarian hormones and stress resilience, female mice also underwent ovariectomy (OVX) surgery and a hormone replacement protocol prior to drug administration. (2S,6S)-HNK and (2R,6R)-HNK protected against distinct stress-induced behaviors in both sexes, with (2S,6S)-HNK attenuating learned fear in male mice, and (2R,6R)-HNK preventing stress-induced depressive-like behavior in both sexes. (R,S)-ketamine and (2R,6R)-HNK, but not (2S,6S)-HNK, attenuated large-amplitude AMPAR-mediated bursts in hippocampal CA3. All three compounds reduced N-methyl-D-aspartate receptor (NMDAR)-mediated currents 1 week after administration. Furthermore, ovarian-derived hormones were necessary for and sufficient to restore (R,S)-ketamine- and (2R,6R)-HNK-mediated prophylaxis in female mice. Our data provide further evidence that resilience-enhancing prophylactics may alter AMPAR-mediated glutamatergic transmission in CA3. Moreover, we show that prophylactics against stress-induced depressive-like behavior can be developed in a sex-specific manner and demonstrate that ovarian hormones are necessary for the prophylactic efficacy of (R,S)-ketamine and (2R,6R)-HNK in female mice.

Binding of the D3-preferring antipsychotic candidate F17464 to dopamine D3 and D2 receptors: a PET study in healthy subjects with [11C]-(+)-PHNO

RATIONALE

F17464, a dopamine D3 receptor antagonist with relatively high D3 selectivity (70 fold vs D2 in vitro), exhibits an antipsychotic profile in preclinical studies, and therapeutic efficacy was demonstrated in a randomized placebo-controlled clinical trial in patients with schizophrenia (Bitter et al. Neuropsychopharmacology 44(11):1917-1924, 2019).

OBJECTIVE

This open-label study in healthy male subjects aimed at characterizing F17464 binding to D3/D2 receptors and the time course of receptor occupancy using positron emission tomography (PET) imaging with a D3-preferring tracer, [¹¹C]-(+)-PHNO.

METHODS

PET scans were performed at baseline and following a single 30 mg or 15 mg dose of F17464 (3 subjects/dose), and blood samples were collected for pharmacokinetic analysis. Receptor occupancy was calculated based upon reduction in binding potential of the tracer following F17464 administration. The relationship between plasma F17464 concentration and D3/D2 receptor occupancy was modeled and the plasma concentration corresponding to 50% receptor occupancy (EC₅₀) calculated.

RESULTS

Both doses of F17464 robustly blocked [¹¹C]-(+)-PHNO D3 receptor binding, with substantial occupancy from 1 h post-administration, which increased at 6-9 h (89-98% and 79-87% for the 30 mg and 15 mg groups, respectively) and remained detectable at 22 h. In contrast, D2 binding was only modestly blocked at all time points (< 18%). F17464 exhibited a combination of rapid peripheral kinetics and hysteresis (persistence of binding 22 h post-dose despite low plasma concentration). The best estimate of the EC₅₀ was 19 ng ml^-1 (~ 40 nM).

CONCLUSION

Overall, F17464 was strongly D3-selective in healthy volunteers, a unique profile for an antipsychotic candidate drug.

Dual pharmacological inhibitor of endocannabinoid degrading enzymes reduces depressive-like behavior in female rats

Major depressive disorder (MDD) is common, often under-treated and a leading cause of disability and mortality worldwide. The causes of MDD remain unclear, including the role of the endocannabinoid system. Intriguingly, the prevalence of depression is significantly greater in women than men. In this study we examined the role of endocannabinoids in depressive behavior. The levels of endocannabinoids, N-arachidonoyl ethanolamide (AEA) and 2-arachidonoyl glycerol (2-AG) were measured along with brain derived neurotrophic factor (BDNF) in postmortem ventral striata of female patients with MDD and non-psychiatric controls, and in Wistar Kyoto (WKY) rat, a selectively inbred strain of rat widely used for testing the depressive behavior. The effect of pharmacological elevation of endocannabinoids through inhibition of their catabolizing enzymes (fatty acid amide hydrolase [FAAH] and monoacyl glycerol lipase [MAGL]) on depressive-like phenotype was also assessed in WKY rat. The findings showed lower levels of endocannabinoids and BDNF in the ventral striata of MDD patients and WKY rats. A dual inhibitor of FAAH and MAGL, JZL195, elevated the endocannabinoids and BDNF levels in ventral striatum, and reduced the depressive-like phenotype in female WKY rats. Collectively, our study suggests a blunted ventral striatal endocannabinoid and BDNF signaling in depressive behavior and concludes that endocannabinoid enhancing agents may have an antidepressant effect.

Sensitive and Selective Liquid-Chromatographic Assay of Fluoxetine and Norfluoxetine in Plasma with Fluorescence Detection After Precolumn Derivatization

We determined fluoxetine (Prozac) and its major metabolite norfluoxetine in plasma by liquid chromatography with fluorescence detection. After liquid-liquid extraction from 1 mL of plasma, the extract was derivatized at room temperature with dansyl chloride, and the highly fluorescent derivatives were chromatographed with a reversed-phase C18 column and a mobile phase of phosphate buffer and acetonitrile. Dansylated fluoxetine, norfluoxetine, and the internal standard were eluted in less than 14 min with no interference from endogenous material. The calibration curve was linear over the concentration range 25-800 micrograms/L with inter- and intra-assay imprecision (CV) of less than 10%. Validity of the assay was checked by comparing results for 110 patients' samples with those by a liquid-chromatographic method with ultraviolet detection (r = 0.993 for fluoxetine, 0.957 for norfluoxetine). The identity of the dansylated derivatives was verified by positive chemical ionization mass spectroscopy. The lower limit of detection was approximately 3 micrograms/L. Because no major antidepressant, neuroleptic, or respective drug metabolites interfere with the quantification of fluoxetine and norfluoxetine, this is a useful procedure for pharmacokinetic studies and in clinical settings.

Ketamine metabolite pilot study in a suicidal depression trial

Ketamine shows promise as a rapidly-acting treatment for depression and suicidal ideation, but side effects and abuse potential limit its use. Understanding its mechanism of action could help develop analogous but safer drugs. This post hoc study explored relationships of ketamine and metabolites, including hydroxynorketamine enantiomers, (2S,6S)- and (2R,6R)-HNK, to clinical response in a subgroup from a published trial in suicidal depression. Depressed adults with clinically significant suicidal ideation were randomized to double-blind infusion of sub-anesthetic ketamine or midazolam. Ketamine and metabolites were measured after infusion (N = 53). Plasma (2R,6R)-HNK was associated with change (higher levels correlated with less clinical improvement) from baseline to 24 h post-infusion of depression (HDRS-24: Spearman r = 0.37, p = 0.009) and suicidal thoughts (SSI: Spearman r = 0.29, p = 0.041). There were similar correlations with weekly follow-up clinical rating scores for both HNK enantiomers and dehydronorketamine (DHNK). Ketamine and norketamine were not associated with change in depression or suicidal ideation (unadjusted p > 0.28).

Brain serotonin transporter binding, plasma arachidonic acid and depression severity: A positron emission tomography study of major depression

BACKGROUND

Serotonin transporter (5-HTT) binding and polyunsaturated fatty acids (PUFAs) are implicated in major depressive disorder (MDD). Links between the two systems in animal models have not been investigated in humans.

METHODS

Using positron emission tomography (PET) and [¹¹C]DASB, we studied relationships between 5-HTT binding potential and plasma levels of PUFAs docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) in medication-free MDD patients (n = 21). PUFAs were quantified using transesterification and gas chromatography. Binding potential BP_P, and alternative outcome measures BP_F and BP_ND, were determined for [¹¹C]DASB in six a priori brain regions of interest (ROIs) using likelihood estimation in graphical analysis (LEGA) to calculate radioligand total distribution volume (V_T), and a validated hybrid deconvolution approach (HYDECA) that estimates radioligand non-displaceable distribution volume (V_ND) without a reference region. Linear mixed models used PUFA levels as predictors and binding potential measures as outcomes across the specified ROIs; age and sex as fixed effects; and subject as random effect to account for across-region binding correlations. As nonlinear relationships were observed, a quadratic term was added to final models.

RESULTS

AA predicted both 5-HTT BP_P and depression severity nonlinearly, described by an inverted U-shaped curve. 5-HTT binding potential mediated the relationship between AA and depression severity.

LIMITATIONS

Given the small sample and multiple comparisons, results require replication.

CONCLUSIONS

Our findings suggest that AA status may impact depression pathophysiology through effects on serotonin transport. Future studies should examine whether these relationships explain therapeutic effects of PUFAs in the treatment of MDD.

Cortisol Stress Response and in Vivo PET Imaging of Human Brain Serotonin 1A Receptor Binding

BACKGROUND

Abnormalities in the hypothalamic-pituitary-adrenal axis, serotonergic system, and stress response have been linked to the pathogenesis of major depressive disorder. State-dependent hyper-reactivity of the hypothalamic-pituitary-adrenal axis is seen in major depressive disorder, and higher binding to the serotonin 1A receptor is observed as a trait in both currently depressed and remitted untreated major depressive disorder. Here, we sought to examine whether a relationship exists between cortisol secretion in response to a stressor and serotonin 1A receptor binding throughout the brain, both in healthy controls and participants with major depressive disorder.

METHODS

Research participants included 42 medication-free, depressed subjects and 31 healthy volunteers. Participants were exposed to either an acute, physical stressor (radial artery catheter insertion) or a psychological stressor (Trier Social Stress Test). Levels of serotonin 1A receptor binding on positron emission tomography with [11C]WAY-100635 were also obtained from all participants. The relationship between [11C]WAY-100635 binding and cortisol was examined using mixed linear effects models with group (major depressive disorder vs control), cortisol, brain region, and their interactions as fixed effects and subject as a random effect.

RESULTS

We found a positive correlation between post-stress cortisol measures and serotonin 1A receptor ligand binding levels across multiple cortical and subcortical regions, independent of diagnosis and with both types of stress. The relationship between [11C]WAY-100635 binding and cortisol was homogenous across all a priori brain regions. In contrast, resting cortisol levels were negatively correlated with serotonin 1A receptor ligand binding levels independently of diagnosis, except in the RN. There was no significant difference in cortisol between major depressive disorder participants and healthy volunteers with either stressor. Similarly, there was no correlation between cortisol and depression severity in either stressor group.

CONCLUSIONS

This study suggests that there may be a common underlying mechanism that links abnormalities in the serotonin system and hypothalamic-pituitary-adrenal axis hyper-reactivity to stress. Future studies need to determine how hypothalamic-pituitary-adrenal axis dysfunction affects mood to increase the risk of suicide in major depression.

Maternal Cerebrospinal Fluid Glutamate in Response to Variable Foraging Demand: Relationship to Cerebrospinal Fluid Serotonin Metabolites in Grown Offspring

Background

Maternal response to allostatic overload during infant rearing may alter neurobiological measures in grown offspring, potentially increasing susceptibility to mood and anxiety disorders. We examined maternal cerebrospinal fluid (CSF) glutamate response during exposure to variable foraging demand (VFD), a bonnet macaque model of allostatic overload, testing whether activation relative to baseline predicted concomitant CSF elevations of the stress neuropeptide, corticotropin-releasing factor. We investigated whether VFD-induced activation of maternal CSF glutamate affects maternal–infant attachment patterns and offspring CSF 5-hydroxyindoleacetic acid concentrations.

Methods

Mother–infant dyads were exposed to the “VFD stressor,” a paradigm in which mothers experience 16 weeks of foraging uncertainty while rearing their infant offspring. Through staggering the infant age of VFD onset, both a cross-sectional design and a longitudinal design were used. Maternal CSF glutamate and glutamine concentrations post-VFD exposure were cross-sectionally compared to maternal VFD naive controls. Proportional change in concentrations of maternal glutamate (and glutamine), a longitudinal measure, was evaluated in relation to VFD-induced elevations of CSF corticotropin-releasing factor. The former measure was related to maternal–infant proximity scores obtained during the final phases of VFD exposure. Maternal glutamatergic response to VFD exposure was used as a predictor variable for young adolescent offspring CSF metabolites of serotonin, dopamine, and norepinephrine.

Results

Following VFD exposure, maternal CSF glutamate concentrations correlated positively with maternal CSF CRF concentrations. Activation relative to baseline of maternal CSF glutamate concentrations following VFD exposure correlated directly with a) increased maternal-infant proximity during the final phases of VFD and b) offspring CSF concentrations of monoamine metabolites including 5-hydroxyindoleacetic acid, which was elevated relative to controls.

Conclusions

Activation of maternal CSF glutamate in response to VFD-induced allostasis is directly associated with elevations of maternal CSF corticotropin-releasing factor. Maternal CSF glutamate alterations induced by VFD potentially compromise serotonin neurotransmission in grown offspring, conceivably modeling human vulnerability to treatment-resistant mood and anxiety disorders.

Ketamine versus midazolam in bipolar depression with suicidal thoughts: A pilot midazolam-controlled randomized clinical trial

OBJECTIVES

To evaluate feasibility and effects of a sub-anesthetic infusion dose of ketamine versus midazolam on suicidal ideation in bipolar depression. Neurocognitive, blood and saliva biomarkers were explored.

METHODS

Sixteen participants with bipolar depression and a Scale for Suicidal Ideation (SSI) score of ≥4 were randomized to ketamine (0.5 mg/kg) or midazolam (0.02 mg/kg). Current pharmacotherapy was maintained excluding benzodiazepines within 24 hours. The primary clinical outcome was SSI score on day 1 post-infusion.

RESULTS

Results supported feasibility. Mean reduction of SSI after ketamine infusion was almost 6 points greater than after midazolam, although this was not statistically significant (estimate=5.84, SE=3.01, t=1.94, P=.074, 95% confidence interval ([CI)]=-0.65 to 12.31). The number needed to treat for response (SSI <4 and at least 50% below baseline) was 2.2, and for remission (SSI=0) was 3.2. The strongest neurocognitive correlation was between memory improvement on the Selective Reminding Test (SRT) and reduction in SSI score on day 1 after ketamine (ρ=-.89, P=.007). Pre- to post-infusion decrease in serum brain derived neurotrophic factor (BDNF) correlated with reduction in SSI from baseline to day 1 after ketamine (n=5, ρ=0.90, P=.037) but not midazolam (P=.087).

CONCLUSIONS

The study demonstrated feasibility. Suicidal thoughts were lower after ketamine than after midazolam at a trend level of significance, likely due to the small pilot sample. Memory improvement and BDNF are promising biomarkers. Replication is needed in an adequately powered full-scale trial.

Lipid correlates of antidepressant response to omega-3 polyunsaturated fatty acid supplementation: A pilot study

Low omega-3 polyunsaturated fatty acid (PUFA) levels are seen in major depression. We examined effects of six weeks of fish oil supplementation on clinical characteristics in 16 patients with symptomatic major depressive disorder, and tested plasma phospholipid levels of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) as correlates of clinical response. Depression symptoms improved after supplementation (p=0.007). The reduction in depression severity was not predicted by baseline PUFA levels but did exhibit a relationship with endpoint PUFAs, correlating negatively with DHA as a percentage of plasma phospholipids (DHA%; R²=0.60, p=0.004), adjusting for endpoint EPA%; and correlating positively with endpoint EPA% (R²=0.58, p=0.007), adjusting for endpoint DHA%. Thus, the higher the proportion of DHA to EPA, the greater the reduction in depression severity (r=-0.43, p=0.097). Five patients showed a decrease of >50% on the 17-item Hamilton Depression Rating Scale and a final score <7 and were thus not only responders but met standard criteria for remission, and were distinguished from non-responders by higher levels of DHA% (p=0.03). This pilot study suggests that post-supplementation DHA% levels may be a necessary target for antidepressant response to fish oil, and that this may depend to some extent on the efficacy of EPA conversion to DHA.

The recency ratio is associated with reduced CSF glutamate in late-life depression

Glutamate is the principal excitatory neurotransmitter in the central nervous system, and is thought to be involved in the process of memory encoding and storage. Glutamate disturbances have also been reported in psychiatric disorders, such as schizophrenia and major depressive disorder (MDD), and in Alzheimer's disease. In this paper, we set out to study the relationship between cerebrospinal fluid (CSF) glutamate levels and memory performance, which we believe has not been reported previously. In particular, we focused on recall performance broken down by serial position. Our prediction was that the recency ratio (Rr), a novel cognitive marker of intellectual impairment, would be linked with CSF glutamate levels. We studied data from a group of cognitively intact elderly individuals, 28 of whom had MDD, while 19 were controls. Study results indicated that Rr levels, but no other memory score, were inversely correlated with CSF glutamate levels, although this was found only in individuals with late-life MDD. For comparison, glutamine or GABA were not correlated with any memory performance measure.

Blunted HPA Axis Activity in Suicide Attempters Compared to those at High Risk for Suicidal Behavior

Studies looking at the relationship of the hypothalamic-pituitary-adrenal (HPA) axis to suicidal behavior and its risk factors, such as depression, childhood abuse, and impulsive aggression, report inconsistent results. These studies also do not always differentiate between subjects who go on to attempt suicide, suicidal subjects who never attempted suicide, and non-suicidal subjects with psychiatric disorders. In this study, we examined cortisol responses to an experimental stressor, the Trier Social Stress Test (TSST), in 208 offspring of parents with mood disorder. Offspring suicide attempters showed lower total cortisol output (β=-0.47, 95% CI (-0.83, -0.11), p=0.01) compared with offspring with suicide-related behavior (SRB) but never attempted, non-suicidal offspring, and a healthy control group. The result remained significant even after controlling for sex, age, race, ethnicity, site, socio-economic status, and hour of the day when the TSST was conducted. Suicide attempters also showed lower baseline cortisol before the TSST (β=-0.45, 95% CI (-0.74, -0.17), p=0.002). However, there were no significant differences between the groups on cortisol reactivity to stress (β=4.5, 95% CI (-12.9, 22), p=0.61). Although subjects with suicide attempt and SRB have similar clinical and psychosocial characteristics, this is the first study to differentiate them biologically on HPA axis indices. Blunted HPA axis activity may increase risk for suicide attempt among individuals with psychopathology by reducing their ability to respond adaptively to ongoing stressors. These results may help better identify subjects at high risk for suicidal behavior for targeted prevention and intervention efforts.

Omega-3 polyunsaturated fatty acid supplementation and white matter changes in major depression

White matter abnormalities are implicated in major depressive disorder (MDD). As omega-3 polyunsaturated fatty acids (PUFAs) are low in MDD and affect myelination, we hypothesized that PUFA supplementation may alleviate depression through improving white matter integrity. Acutely depressed MDD patients (n = 16) and healthy volunteers (HV, n = 12) had 25-direction diffusion tensor imaging before and after 6 weeks of fish oil supplementation. Plasma phospholipid omega-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and omega-6 PUFA arachidonic acid (AA) levels were determined before and after supplementation using high-throughput extraction and gas chromatography and expressed as a percentage of total phospholipids (PUFA%). Fractional anisotropy (FA) was computed using a least-squares-fit diffusion tensor with non-linear optimization. Regression analyses were performed with changes in PUFA levels or Hamilton Depression Rating Scale scores as predictors, voxel-wise difference maps of FA as outcome, covariates age and sex, with family-wise correction for multiple comparisons. Increases in plasma phospholipid DHA% (but not EPA% or AA%) after fish oil predicted increases in FA in MDD but not HV, in a cluster including genu and body of the corpus callosum, and anterior corona radiata and cingulum (cluster-level p < 0.001, peak t-score = 8.10, p = 0.002). There was a trend for greater change in FA in MDD responders over nonresponders (t = -1.874, df = 13.56, p = 0.08). Decreased depression severity predicted increased FA in left corticospinal tract and superior longitudinal fasciculus (cluster-level p < 0.001, peak t-score = 5.04, p = 0.0001). Increased FA correlated with increased DHA% and decreased depression severity after fish oil supplementation suggests therapeutic effects of omega-3 PUFAs may be related to improvements in white matter integrity.

Further evidence of low baseline cortisol levels in suicide attempters

BACKGROUND

Many, but not all studies of suicide attempters' cortisol response to stress-either social stress or pharmacological challenge-report an exaggerated response. Recent studies of resting baseline cortisol in past suicide attempters, however, have found lower baseline levels.

METHODS

In this study, baseline salivary cortisols were obtained prior to a stress procedure from adults with lifetime diagnoses of a mood disorder (N=69), 31.9% of whom had made a prior suicide attempt. Data were collected during the piloting of this stress procedure, at various times of day and with/without an additional confederate in the room.

RESULTS

Adjusting for procedural, demographic and clinical variables that affect salivary cortisol levels-including time of day of sampling, order of procedure with respect to other assessments, past alcohol abuse, current medication use, and bipolar diagnosis-past suicide attempters had lower baseline cortisol levels compared to non-attempters.

LIMITATIONS

This is a pilot study with modest sample sizes using statistical, rather than experimental control of numerous variables affecting salivary cortisol levels.

CONCLUSIONS

Results confirm previous studies. Low baseline cortisol levels have been associated with childhood adversity and externalizing disorders, suggesting a potential role in reducing inhibitions for risky and dangerous behaviors. Further research is needed to more fully characterize these associations and their role in suicidal behavior risk.

DNA methylation perturbations in genes involved in polyunsaturated Fatty Acid biosynthesis associated with depression and suicide risk

Polyunsaturated fatty acid (PUFA) status has been associated with neuropsychiatric disorders, including depression and risk of suicide. Long-chain PUFAs (LC-PUFAs) are obtained in the diet or produced by sequential desaturation and elongation of shorter-chain precursor fatty acids linoleic acid (LA, 18:2n-6) and α-linolenic acid (ALA, 18:3n-3). We compared DNA methylation patterns in genes involved in LC-PUFA biosynthesis in major depressive disorder (MDD) with (n = 22) and without (n = 39) history of suicide attempt, and age- and sex-matched healthy volunteers (n = 59). Plasma levels of selected PUFAs along the LC-PUFA biosynthesis pathway were determined by transesterification and gas chromatography. CpG methylation levels for the main human LC-PUFA biosynthetic genes, fatty acid desaturases 1 (Fads1) and 2 (Fads2), and elongation of very long-chain fatty acids protein 5 (Elovl5), were assayed by bisulfite pyrosequencing. Associations between PUFA levels and diagnosis or suicide attempt status did not survive correction for multiple testing. However, MDD diagnosis and suicide attempts were significantly associated with DNA methylation in Elovl5 gene regulatory regions. Also the relative roles of PUFA levels and DNA methylation with respect to diagnostic and suicide attempt status were determined by least absolute shrinkage and selection operator logistic regression analyses. We found that PUFA associations with suicide attempt status were explained by effects of Elovl5 DNA methylation within the regulatory regions. The observed link between plasma PUFA levels, DNA methylation, and suicide risk may have implications for modulation of disease-associated epigenetic marks by nutritional intervention.

Anxiety in major depression and cerebrospinal fluid free gamma-aminobutyric acid

BACKGROUND

Low gamma-aminobutyric acid (GABA) is implicated in both anxiety and depression pathophysiology. They are often comorbid, but most clinical studies have not examined these relationships separately. We investigated the relationship of cerebrospinal fluid (CSF) free GABA to the anxiety and depression components of a major depressive episode (MDE) and to monoamine systems.

METHODS AND MATERIALS

Patients with a DSM-IV major depressive episode (N = 167: 130 major depressive disorder; 37 bipolar disorder) and healthy volunteers (N = 38) had CSF free GABA measured by gas chromatography mass spectroscopy. Monoamine metabolites were assayed by high performance liquid chromatography. Symptomatology was assessed by Hamilton depression rating scale.

RESULTS

Psychic anxiety severity increased with age and correlated with lower CSF free GABA, controlling for age. CSF free GABA declined with age but was not related to depression severity. Other monoamine metabolites correlated positively with CSF GABA but not with psychic anxiety or depression severity. CSF free GABA was lower in MDD compared with bipolar disorder and healthy volunteers. GABA levels did not differ based on a suicide attempt history in mood disorders. Recent exposure to benzodiazepines, but not alcohol or past alcoholism, was associated with a statistical trend for more severe anxiety and lower CSF GABA.

CONCLUSIONS

Lower CSF GABA may explain increasing severity of psychic anxiety in major depression with increasing age. This relationship is not seen with monoamine metabolites, suggesting treatments targeting the GABAergic system should be evaluated in treatment-resistant anxious major depression and in older patients.

Combined dexamethasone suppression-corticotrophin-releasing hormone stimulation test in medication-free major depression and healthy volunteers

BACKGROUND

The hypothalamic-pituitary-adrenal (HPA) axis is dysfunctional in a subgroup of mood disorders.

METHODS

We compared cortisol and adrenocorticotropic hormone (ACTH) responses in major depression and healthy volunteers to the combined dexamethasone suppression-corticotrophin-releasing hormone stimulation (DEX-CRH) test. Unlike other published studies, the study patients were medication-free and the healthy volunteers did not have first-degree relatives with a mood or psychotic disorder. Demographics, DSM-IV diagnoses and other clinical parameters were evaluated in major depressive disorder (MDD) and healthy control groups. Participants received an oral dose of 1.5mg dexamethasone at 11 pm the day before CRH administration. On the following day, at 3 pm, 100 µg of ovine CRH was infused. Blood samples for determination of cortisol and ACTH were collected every 15 min from 3 pm to 4:15 pm. Cortisol and ACTH responses were calculated as areas under the curve.

RESULTS

Controlling for age, baseline (i.e., post-dexamethasone) ACTH levels were higher in depressed patients compared to controls (p=0.01). There was a trend for higher ACTH responses in depressed patients compared to the control group (p=0.08). In depressed patients, cortisol and ACTH responses correlated positively with age, duration of illness and number of hospitalizations.

LIMITATIONS

Because of the cross-sectional study design we can only evaluate the nature of potential HPA axis disturbances that were present in patients when they are acutely depressed.

CONCLUSIONS

Feedback inhibition of ACTH secretion by cortisol is compromised in MDD, and this is independent of an age effect on the HPA axis function.

Omega-3 polyunsaturated fatty acid (PUFA) status in major depressive disorder with comorbid anxiety disorders

BACKGROUND

Although lower levels of omega-3 polyunsaturated fatty acids (PUFAs) are found in major depressive disorder, less is known about PUFA status and anxiety disorders.

METHOD

Medication-free participants with DSM-IV-defined major depressive disorder (MDD), with (n = 18) and without (n = 41) comorbid DSM-IV anxiety disorders, and healthy volunteers (n = 62) were recruited from October 2006 to May 2010 for mood disorder studies at the New York State Psychiatric Institute. Participants were 18-73 years of age (mean age, 35.8 ± 12.6 years). Depression and anxiety severity was assessed using depression and anxiety subscales from the 17-item Hamilton Depression Rating Scale. Plasma PUFAs eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) and the ratio of arachidonic acid (AA; 22:4n-6) to EPA (AA:EPA) were quantified. This secondary analysis employed analysis of variance with a priori planned contrasts to test for diagnostic group differences in log-transformed PUFA levels (logDHA, logEPA, and logAA:EPA).

RESULTS

Plasma levels of logDHA (F(2,118) = 4.923, P = .009), logEPA (F(2,118) = 6.442, P = .002), and logAA:EPA (F(2,118) = 3.806, P = .025) differed across groups. Participants with MDD had lower logDHA (t(118) = 2.324, P = .022) and logEPA (t(118) = 3.175, P = .002) levels and higher logAA:EPA levels (t(118) = -2.099, P = .038) compared with healthy volunteers. Lower logDHA (t(118) = 2.692, P = .008) and logEPA (t(118) = 2.524, P = .013) levels and higher logAA:EPA levels (t(118) = -2.322, P = .022) distinguished anxious from nonanxious MDD. Depression severity was not associated with PUFA plasma levels; however, anxiety severity across the entire sample correlated negatively with logDHA (r(p) = -0.22, P = .015) and logEPA (r(p) = -0.25, P = .005) levels and positively with logAA:EPA levels (r(p) = 0.18, P = .043).

CONCLUSIONS

The presence and severity of comorbid anxiety were associated with the lowest EPA and DHA levels. Further studies are needed to elucidate whether omega-3 PUFA supplementation may preferentially alleviate MDD with more severe anxiety.

Preliminary findings on the interactive effects of IV ethanol and IV nicotine on human behavior and cognition: a laboratory study

INTRODUCTION

There are mixed reports on nicotine's effects on alcohol-induced impairment in cognitive performance and behavior in humans. The main objective of this study was to characterize the interactive effects of acute intravenous (IV) alcohol and nicotine administration on behavior and cognition in healthy nonsmokers.

METHODS

Healthy subjects aged 21-44 years participated in 3 test days. On each test day, they received in a double-blind randomized manner one of three IV alcohol infusion conditions using a "clamp": placebo, targeted breathalyzer of 40 mg%, or targeted breathalyzer of 80 mg%. Alcohol infusion was delivered over 20 min and lasted for 120 min. They also received both placebo and active nicotine in a fixed order delivered intravenously. Placebo nicotine was delivered first over 10 min at the timepoint when the breath alcohol was "clamped"; active nicotine (1.0 mcg/kg/min) was delivered for 10 min, 70 min after the alcohol infusion was clamped. Subjective effects of alcohol were measured using the Biphasic Alcohol Effects Scale and the Number of Drinks Scale. Cognitive inhibition and attention were measured by the Continuous Performance Task-Identical Pairs and working memory by the Rey Auditory Verbal Learning Task (RAVLT).

RESULTS

Nicotine significantly reversed subjective intoxication and sedation of alcohol at the low dose. Alcohol impaired performance on the RAVLT, and nicotine further impaired verbal learning and recall at both doses of alcohol.

CONCLUSIONS

The data showed that nicotine had an effect on subjective alcohol effects but did not reverse and actually worsened alcohol-induced deficits in memory.

Cannabinoid receptor 1 signaling in embryo neurodevelopment

In utero exposure to tetrahydrocannabinol, the psychoactive component of marijuana, is associated with an increased risk for neurodevelopmental defects in the offspring by interfering with the functioning of the endocannabinoid (eCB) system. At the present time, it is not clearly known whether the eCB system is present before neurogenesis. Using an array of biochemical techniques, we analyzed the levels of CB1 receptors, eCBs (AEA and 2-AG), and the enzymes (NAPE-PLD, DAGLα, DAGLβ, MAGL, and FAAH) involved in the metabolism of the eCBs in chick and mouse models during development. The findings demonstrate the presence of eCB system in early embryo before neurogenesis. The eCB system might play a critical role in early embryogenesis and there might be adverse developmental consequences of in utero exposure to marijuana and other drugs of abuse during this period.

Innate difference in the endocannabinoid signaling and its modulation by alcohol consumption in alcohol-preferring sP rats

The present study was undertaken to examine whether genetically predetermined differences in components of the endocannabinoid system were present in the brain of Sardinian alcohol-preferring (sP) and Sardinian alcohol-non-preferring (sNP) rats, a pair of rat lines selectively bred for opposite alcohol preference. The effects of acquisition and maintenance of alcohol drinking, alcohol withdrawal, and alcohol re-exposure on the endocannabinoid system was also assessed in the striatum of sP rats. The findings revealed significantly higher density of the CB1 receptors and levels of CB1 receptor mRNA, CB1 receptor-mediated G-protein coupling, and endocannabinoids in the cerebral cortex, hippocampus and striatum of alcohol-naive sP rats than sNP rats. A significantly lower expression of mFAAH enzyme was evident in the hippocampus of alcohol-naive sP rats. Alcohol drinking (during both acquisition and maintenance phases) in sP rats resulted in a significant reduction in striatal CB1 receptor-mediated G-protein coupling whereas alcohol withdrawal attenuated this effect. Alcohol consumption was also associated with markedly increased levels of endocannabinoids in the striatum. Co-administration of the CB1 receptor antagonist, rimonabant (SR141716A) reduced alcohol intake, and reversed alcohol-induced changes in CB1 receptor-mediated G-protein activation. These findings provided a new insight into a potential genetic basis of excessive alcohol consumption, suggesting innate differences in the endocannabinoid system might be associated with higher alcohol preference in sP rats. The data also indicate a modulation of CB1 receptor-mediated signaling following alcohol consumption, and further strengthen the potential of the endocannabinoid system as a target for the treatment of alcohol related behaviors.

Validation of a food frequency questionnaire to assess intake of n-3 polyunsaturated fatty acids in subjects with and without major depressive disorder

The role of n-3 polyunsaturated fatty acids (PUFAs) in psychiatric illness is a topic of public health importance. This report describes development and biomarker validation of a 21-item, self-report food frequency questionnaire (FFQ) intended for use in psychiatric research to assess intake of α-linolenic acid (18:3n-3 [ALA]), docosahexaenoic acid (22:6n-3 [DHA]), and eicosapentaenoic acid (20:5n-3 [EPA]). In a cross-sectional study conducted from September 2006 to September 2008, sixty-one ethnically diverse adult participants with (n=34) and without (n=27) major depressive disorder completed this n-3 PUFA FFQ and provided a plasma sample. Plasma levels of n-3 PUFAs EPA and DHA, and n-6 PUFA arachidonic acid (20:4n-6 [AA]) were quantified by gas chromatography. Using Spearman's ρ, FFQ-estimated intake correlated with plasma levels of DHA (r=0.50; P<0.0001) and EPA (r=0.38; P=0.002), but not with ALA levels (r=0.22; P=0.086). Participants were classified into quartiles by FFQ-estimated intake and plasma PUFA concentrations. Efficacy of the FFQ to rank individuals into same or adjacent plasma quartiles was 83% for DHA, 78.1% for EPA, and 70.6% for ALA; misclassification into extreme quartiles was 4.9% for DHA, 6.5% for EPA, and 8.2% for ALA. FFQ-estimated EPA intake and plasma EPA were superior to plasma AA levels as predictors of the plasma AA to EPA ratio. This brief FFQ can provide researchers and clinicians with valuable information concerning dietary intake of DHA and EPA.

Antipsychotic-induced vacuous chewing movements and extrapyramidal side effects are highly heritable in mice

Pharmacogenomics is yet to fulfill its promise of manifestly altering clinical medicine. As one example, a predictive test for tardive dyskinesia (TD) (an adverse drug reaction consequent to antipsychotic exposure) could greatly improve the clinical treatment of schizophrenia but human studies are equivocal. A complementary approach is the mouse-then-human design in which a valid mouse model is used to identify susceptibility loci, which are subsequently tested in human samples. We used inbred mouse strains from the Mouse Phenome Project to estimate the heritability of haloperidol-induced activity and orofacial phenotypes. In all, 159 mice from 27 inbred strains were chronically treated with haloperidol (3 mg kg(-1) per day via subdermal slow-release pellets) and monitored for the development of vacuous chewing movements (VCMs; the mouse analog of TD) and other movement phenotypes derived from open-field activity and the inclined screen test. The test battery was assessed at 0, 30, 60, 90 and 120 days in relation to haloperidol exposure. As expected, haloperidol caused marked changes in VCMs, activity in the open field and extrapyramidal symptoms (EPS). Unexpectedly, factor analysis demonstrated that these measures were imprecise assessments of a latent construct rather than discrete constructs. The heritability of a composite phenotype was ∼0.9 after incorporation of the longitudinal nature of the design. Murine VCMs are a face valid animal model of antipsychotic-induced TD, and heritability estimates from this study support the feasibility of mapping of susceptibility loci for VCMs.

Selective alterations of the CB1 receptors and the fatty acid amide hydrolase in the ventral striatum of alcoholics and suicides

Recent studies in rodents have suggested a role for the central endocannabinoid system in the regulation of mood and alcohol related behaviors. Alcohol use disorder is often associated with suicidal behavior. In the present study, we examined whether abnormalities in the endocannabinoid system in the ventral striatum are associated with alcohol dependence and suicide. The levels of CB1 receptors, receptor-mediated G-protein signaling, and activity and level of the fatty acid amide hydrolase (FAAH) were analyzed postmortem in the ventral striatum of alcohol-dependent nonsuicides (CA, n=9), alcohol-dependent suicides (AS, n=9) and nonpsychiatric controls (C, n=9). All subjects underwent a psychological autopsy, and toxicological and neuropathological examinations. The levels of the CB1 receptors and the CB1 receptor-mediated G-protein signaling were significantly lower in the ventral striatum of CA compared to the control group. However, these parameters were elevated in AS when compared to CA group. The activity of FAAH enzyme was lower in CA compared to the control group while it was found to be significantly higher in AS compared with CA group. These findings suggest that alcohol dependence is associated with the downregulation of the CB1 receptors, while suicide is linked to the upregulation of these receptors in the ventral striatum. Alteration in the activity of FAAH enzyme that regulates the anandamide (AEA) content might in turn explain differences in the CB1 receptor function in alcohol dependence and suicide. These findings may have etiological and therapeutic implications for the treatment of alcohol addiction and suicidal behavior.

Combined catecholamine and indoleamine depletion following response to ECT

The mechanism of action of electroconvulsive therapy (ECT) in treating major depression is unknown. We studied two candidate mechanisms through inhibiting simultaneously the synthesis of noradrenaline and serotonin in patients immediately after successful treatment with ECT using a randomised, placebo-controlled, double-blind crossover design. There were no significant changes in depression scores under any experimental conditions, or between the amine-depleted and placebo groups despite reductions of 61% in serum homovanillic acid, 47% in 3-methoxy-4-hydroxyenylethyleneglycol, and 89% in serum tryptophan. Catecholamine and serotonin availability may not be necessary for maintaining the initial antidepressant response to ECT.

Future suicide attempt and responses to serotonergic challenge

Blunted neurohormonal responses to serotonergic agents are found in major depression and suicidal behavior, but there have been no prospective studies of their relationship to later suicide attempt. In this study, healthy volunteers and depressed subjects were administered a fenfluramine (FEN) and placebo challenge test at baseline and then followed for 2 years. Seven subjects made suicide attempts within the follow-up period. Healthy volunteers, depressed non-attempters, depressed past suicide attempters, and depressed future attempters were compared on plasma prolactin and cortisol responses, as well as on mood (Profile of Mood States; POMS) and behavioral measures that were assessed at baseline and at the end of each challenge testing day. Both past and future attempters had lower total prolactin output (area under the curve) in response to FEN relative to non-patients. Future attempters had lower cortisol response relative to all other groups. All subject groups reported a decrease in POMS Fatigue subscale score and increase in finger tapping rate after receiving FEN. Depressed subjects reported a significant decline in POMS Total, Depression, and Tension/Anxiety scores, but future attempters' did not, showing a slight mean increase. Lower cortisol response correlated with greater suicidal ideation 3 months and 1 year post-study. Logistic regression revealed that blunting of cortisol response and worsening of mood after FEN, and younger age could be used to predict later suicide attempt in the majority of cases (4/7). Results suggest that blunted cortisol and unfavorable acute mood response to serotonergic challenge, in the context of the general activating effects of these drugs, may be a risk factor for later suicide attempt.

Increased synaptic dopamine function in associative regions of the striatum in schizophrenia

CONTEXT

A long-standing version of the dopamine hypothesis of schizophrenia postulates that hyperactivity of dopaminergic transmission at D(2) receptors in the limbic striatum is associated with the illness and that blockade of mesolimbic D(2) receptors is responsible for the antipsychotic action of D(2) receptor antagonists.

OBJECTIVE

To localize dopaminergic hyperactivity within the striatum in schizophrenia.

DESIGN

Case-control study.

SETTING

Inpatient research unit.

PARTICIPANTS

Eighteen untreated patients with schizophrenia and 18 healthy control subjects matched for age, sex, ethnicity, parental socioeconomic status, cigarette smoking, and weight.

MAIN OUTCOME MEASURES

Percentage change in dopamine D(2) receptor availability in striatal subregions within each subject measured by positron emission tomography with carbon 11-labeled raclopride before and during pharmacologically induced dopamine depletion.

RESULTS

In the associative striatum, acute dopamine depletion resulted in a larger increase in D(2) receptor availability in patients with schizophrenia (mean [SD], 15% [7%]) than in control subjects (10% [7%], P = .045), suggesting higher synaptic dopamine concentration. Within the associative striatum, this effect was most pronounced in the precommissural dorsal caudate (15% [8%] in patients vs 9% [8%] in controls, P = .03). No between-group differences were observed in the limbic and sensorimotor striatum.

CONCLUSIONS

These findings suggest that schizophrenia is associated with elevated dopamine function in associative regions of the striatum. Because the precommissural dorsal caudate processes information from the dorsolateral prefrontal cortex, this observation also suggests that elevated subcortical dopamine function might adversely affect performance of the dorsolateral prefrontal cortex in schizophrenia. On the other hand, the absence of a group difference in the limbic striatum brings into question the therapeutic relevance of the mesolimbic selectivity of second-generation antipsychotic drugs.

Sex-specific effects of chronic fluoxetine treatment on neuroplasticity and pharmacokinetics in mice

Neurogenesis is a mechanism through which antidepressants may produce therapeutic effects. There is a dearth of information regarding the effects of antidepressants on neurogenesis and neurotrophin mobilization in females. This study examined sex differences in the alteration of cell proliferation and survival in multiple regions of the brain. Additional experiments examined brain-derived neurotrophic factor (BDNF) levels and pharmacokinetics of fluoxetine to determine whether they mediate sex differences. MRL/MpJ mice were treated with fluoxetine (5 and 10 mg/kg b.i.d.) for 21 days and received injections of 5-bromo-2'-deoxyuridine (200 mg/kg) to measure DNA synthesis. In the hippocampus, fluoxetine increased cell proliferation at both doses; females treated with 10 mg/kg produced more new cells than males. Fluoxetine did not alter survival in males, but 10 mg/kg reduced survival in females. In the frontal cortex, fluoxetine increased cell proliferation and survival in males treated with 10 mg/kg. In the cerebellum and amygdala, 10 mg/kg fluoxetine increased cell proliferation in both sexes but did not alter the incorporation of the new cells. Fluoxetine increased BDNF levels in the hippocampus of both sexes. BDNF levels correlated with cell proliferation in males but not females. Brain and plasma levels indicated that females metabolized fluoxetine faster than males and produced more of the metabolite norfluoxetine. These data suggest that fluoxetine acts on multiple areas of the brain to increase cell proliferation, and the pattern of activation differs between males and females. Sex-specific effects of fluoxetine on neurotrophin mobilization and pharmacokinetics may contribute to these differences in neural plasticity.

Positron emission tomography imaging of amphetamine-induced dopamine release in the human cortex: a comparative evaluation of the high affinity dopamine D2/3 radiotracers [11C]FLB 457 and [11C]fallypride

The use of PET and SPECT endogenous competition binding techniques has contributed to the understanding of the role of dopamine in several neuropsychiatric disorders. An important limitation of these imaging studies is the fact that measurements of acute changes in synaptic dopamine have been restricted to the striatum. The ligands previously used, such as [(11)C]raclopride and [(123)I]IBZM, do not provide sufficient signal to noise ratio to quantify D(2) receptors in extrastriatal areas, such as cortex, where the concentration of D(2) receptors is much lower than in the striatum. Given the importance of cortical DA function in cognition, a method to measure cortical dopamine function in humans would be highly desirable. The goal of this study was to compare the ability of two high affinity DA D(2) radioligands [(11)C]FLB 457 and [(11)C]fallypride to measure amphetamine-induced changes in DA transmission in the human cortex. D(2) receptor availability was measured in the cortical regions of interest with PET in 12 healthy volunteers under control and postamphetamine conditions (0.5 mg kg(-1), oral), using both [(11)C]FLB 457 and [(11)C]fallypride (four scans per subjects). Kinetic modeling with an arterial input function was used to derive the binding potential (BP(ND)) in eight cortical regions. Under controlled conditions, [(11)C]FLB 457 BP(ND) was 30-70% higher compared with [(11)C]fallypride BP(ND) in cortical regions. Amphetamine induced DA release led to a significant decrease in [(11)C]FLB 457 BP(ND) in five out the eight cortical regions evaluated. In contrast, no significant decrease in [(11)C]fallypride BP(ND) was detected in cortex following amphetamine. The difference between [(11)C]FLB 457 and [(11)C]fallypride ability to detect changes in the cortical D(2) receptor availability following amphetamine is related to the higher signal to noise ratio provided by [(11)C]FLB 457. These findings suggest that [(11)C]FLB 457 is superior to [(11)C]fallypride for measurement of changes in cortical synaptic dopamine.

The apolipoprotein E epsilon4 allele and memory performance in HIV-1 seropositive subjects: differences at baseline but not after acute oral lorazepam challenge

RATIONALE

The APOE epsilon4 allele, an established genetic risk factor for late-onset Alzheimer's disease, has been linked to an increased risk for dementia especially in older individuals with HIV-1 infection. This allele has also been associated with increased memory impairment following oral lorazepam challenge in healthy elderly. Lorazepam and other benzodiazepines are widely prescribed in individuals with HIV-1 infection who are at increased risk for cognitive impairment.

OBJECTIVE

The aim of this study was to examine if the epsilon4 allele influences lorazepam-induced memory deficits in this population.

MATERIALS AND METHODS

Forty-one non-demented, HIV-1 seropositive adults (15 epsilon4 carriers, mean age = 43.47 +/- 8.25; 26 epsilon4 non-carriers, mean age = 46.77 +/- 8.56) participated in a double-blind, placebo-controlled crossover design, receiving single acute oral doses of lorazepam 0.5, 1.0 mg, or placebo over three sessions, each 1 week apart. Standardized neuropsychological assessments, including measures of immediate and delayed verbal recall, were conducted at baseline and at 1, 2.5, and 5 h post-drug administration in each condition.

RESULTS

Acute lorazepam administration produced dose- and time-dependent impairments in measures of verbal recall. However, the e4 allele did not modulate these adverse effects. An APOE epsilon4 group by time interaction was also found such that the APOE-epsilon4-positive subjects had significantly better immediate and delayed verbal recall than the negative subjects at baseline assessment, but the groups did not significantly differ at any subsequent time point.

CONCLUSION

Future studies should clarify the role of epsilon4 in the modulation of drug-induced cognitive toxicity and baseline performance and their relationship to progressive decline, especially in older individuals with HIV-1 infection, a group at increased risk for dementia.

Genetic and pharmacological manipulations of the CB(1) receptor alter ethanol preference and dependence in ethanol preferring and nonpreferring mice

Recent studies have indicated a role for the endocannabinoid system in ethanol-related behaviors. This study examined the effect of pharmacological activation, blockade, and genetic deletion of the CB(1) receptors on ethanol-drinking behavior in ethanol preferring C57BL/6J (B6) and ethanol nonpreferring DBA/2J (D2) mice. The deletion of CB(1) receptor significantly reduced the ethanol preference. Although the stimulation of the CB(1) receptor by CP-55,940 markedly increased the ethanol preference, this effect was found to be greater in B6 than in D2 mice. The antagonism of CB(1) receptor function by SR141716A led to a significant reduction in voluntary ethanol preference in B6 than D2 mice. A significant lower hypothermic and greater sedative response to acute ethanol administration was observed in both the strains of CB(1) -/- mice than wild-type mice. Interestingly, genetic deletion and pharmacological blockade of the CB(1) receptor produced a marked reduction in severity of handling-induced convulsion in both the strains. The radioligand binding studies revealed significantly higher levels of CB(1) receptor-stimulated G-protein activation in the striatum of B6 compared to D2 mice. Innate differences in the CB(1) receptor function might be one of the contributing factors for higher ethanol drinking behavior. The antagonists of the CB(1) receptor may have therapeutic potential in the treatment of ethanol dependence.

Serotonergic responses in depressed patients with or without a history of alcohol use disorders and healthy controls

Dysfunction of serotonergic neurotransmission has been implicated in the etiopathogenesis of major depression (MDD) and alcohol use disorders (AUD). To compare serotonin function in MDD with co-occurring AUD (MDD/AUD), MDD without co-occurring AUD (MDD only) and healthy controls (HC) we sought to study differences in prolactin responses to fenfluramine administration in patients with MDD/AUD, patients with MDD only and HC. In all, 169 subjects (62 MDD/AUD, 75 MDD only, and 32 HC) were entered into the study. Controlling for gender, prolactin responses were lower in the MDD/AUD group compared to the MDD only or the HC group. Controlling for gender and aggression, prolactin responses in the MDD/AUD group remained significantly lower compared to the HC group but the difference between the MDD/AUD and the MDD only groups disappeared. The difference in prolactin responses between MDD/AUD and MDD only could be attributed to higher aggression scores in the MDD/AUD group compared to the MDD group.

Characterization of interactions between phencyclidine and amphetamine in rodent prefrontal cortex and striatum: Implications in NMDA/glycine-site-mediated dopaminergic dysregulation and dopamine transporter function

N-Methyl-D-aspartate (NMDA) antagonists induced behavioral and neurochemical changes in rodents that serve as animal models of schizophrenia. Chronic phencyclidine (PCP, 15 mg/(kg day) for 3 weeks via Alzet osmotic pump) administration enhances the amphetamine (AMPH)-induced dopamine (DA) efflux in prefrontal cortex (PFC), similar to that observed in schizophrenia. NMDA/glycine-site agonists, such as glycine (GLY), administered via dietary supplementation, reverse the enhanced effect. The present study investigated mechanisms of glycine-induced reversal of PCP-induced stimulation of AMPH-induced DA release, using simultaneous measurement of DA and AMPH in brain microdialysate, as well as peripheral and tissue AMPH levels. PCP treatment, by itself, increased peripheral and central AMPH levels, presumably via interaction with hepatic enzymes (e.g. cytochrome P450 CYP2C11). GLY (16% diet) had no effect on peripheral AMPH levels in the presence of PCP. Nevertheless, GLY significantly reduced extracellular/tissue AMPH ratios in both PFC and striatum (STR), especially following PCP administration, suggesting a feedback mediated effect on the dopamine transporter. GLY also inhibited acute AMPH (5 mg/kg)-induced DA release in PFC, but not STR. These findings suggest that GLY may modulate DA release in brain by producing feedback regulation of dopamine transporter function, possibly via potentiation of NMDA-stimulated GABA release and presynaptic GABAB receptor activation. The present studies also demonstrate pharmacokinetic interaction between AMPH and PCP, which may be of both clinical and research relevance.

Positron emission tomography study of regional brain metabolic responses to a serotonergic challenge in major depressive disorder with and without comorbid lifetime alcohol dependence

This is the first study contrasting regional glucose metabolic rate (rCMRglu) responses to a serotonergic challenge in major depressive disorder (MDD) with and without comorbid alcohol dependence. In a university hospital, patients with MDD without a history of alcohol dependence (MDD only) and patients with MDD and comorbid alcohol dependence (MDD/ALC) were enrolled in this study. Subjects with comorbid borderline personality disorder were excluded. A bolus injection of approximately 5 mCi of (18)fluorodeoxyglucose was administered 3 h after the administration of placebo or fenfluramine. We found an anterior medial prefrontal cortical area where MDD/ALC subjects had more severe hypofrontality than MDD only patients. This area encompassed the left medial frontal and left and right anterior cingulate gyri. This group difference disappeared after fenfluramine administration. The fact that the observed group difference disappeared after the fenfluramine challenge suggests that serotonergic mechanisms play a role in the observed differences between the groups.

Transient cerebral hypoperfusion enhances intraarterial carmustine deposition into brain tissue

We hypothesized that bolus injections of lipid soluble chemotherapeutic drugs during transient cerebral hypoperfusion could significantly boost regional drug delivery. In the first two groups of New Zealand White rabbits we measured brain tissue carmustine concentrations after intravenous infusion, intraarterial infusion with normal perfusion, and after intraarterial injections during transient cerebral hypoperfusion. In the third group of animals we assessed the safety of the technique by assessing electroencephalographic changes for 6 h after flow arrest carmustine administration and subsequent histological examination. The brain tissue carmustine concentrations were fivefold to sevenfold higher when the drug was injected during cerebral hypoperfusion compared to a conventional intracarotid infusion (68.4 +/- 24.5 vs. 14.2 +/- 8.3 microg/g, n = 5 each, respectively, P < 0.0001). The brain tissue carmustine concentrations (y) were a linear function of the bolus dose (x) injected during cerebral hypoperfusion, y = 10.4 x x - 21 (R = 0.84, P < 0.001). Stable EEGs were recorded several hours after flow arrest carmustine exposure and histological examinations did not reveal any gross evidence of cerebral injury. Transient cerebral hypoperfusion during intraarterial bolus injection of carmustine significantly increases drug delivery. Clinical techniques that decrease CBF, such as, transient arterial occlusion by balloon tipped catheters, hyperventilation, hypothermia, induced hypotension, or transient circulatory arrest, could enhance intraarterial drug delivery to the brain. We believe that the mechanisms for improved drug delivery is the decrease in drug dilution by reduced or absent blood flow, decreased protein binding and a longer time for high concentrations of free drugs to transit through the blood brain barrier.

Amphetamine-induced dopamine release: markedly blunted in cocaine dependence and predictive of the choice to self-administer cocaine

OBJECTIVE

Dopamine is an important mediator of the reinforcing effects of cocaine, and alterations in dopamine function might be involved in cocaine dependence. The goals of the present study were to characterize pre- and postsynaptic dopamine function in recently detoxified cocaine-dependent subjects. Specifically, dopamine response to an acute amphetamine challenge was assessed in striatal subregions in cocaine-dependent and healthy comparison participants using positron emission tomography (PET). Furthermore, the relationship between this dopamine response and the choice to self-administer cocaine in a laboratory model of relapse was investigated.

METHOD

Twenty-four cocaine-dependent participants and 24 matched healthy subjects underwent [(11)C]raclopride scans under a baseline condition and following intravenous amphetamine administration (0.3 mg/kg). Cocaine-dependent participants also completed cocaine self-administration sessions in which a priming dose of cocaine was followed by the choice to either self-administer subsequent cocaine doses or receive a monetary reward.

RESULTS

Cocaine dependence was associated with a marked reduction in amphetamine-induced dopamine release in each of the functional subregions of the striatum (limbic striatum: -1.2% in cocaine-dependent participants versus -12.4% in healthy subjects; associative striatum: -2.6% versus -6.7%, respectively; sensorimotor striatum: -4.3% versus -14.1%). Blunted dopamine transmission in the ventral striatum and anterior caudate was predictive of the choice for cocaine over money.

CONCLUSIONS

Cocaine dependence is associated with impairment of dopamine function, and this impairment appears to play a critical role in relapse.

Weight gain during a double-blind multidosage clozapine study

Possible variables associated with weight gain during clozapine treatment include dosing, treatment duration, baseline body mass index (BMI), sex, and plasma norclozapine concentrations. Weight gains during a double-blind, randomized clozapine study using 100-, 300-, and 600-mg/d doses were analyzed. It was hypothesized that weight gain was associated with baseline BMI, clozapine dosing, and demographic factors. The possible contribution of plasma clozapine and norclozapine concentrations was explored. Fifty treatment-refractory schizophrenia patients were randomized to 100-, 300-, or 600-mg/d doses of clozapine for a 16-week, double-blind treatment in a research ward. Nonresponsive patients went onto a second and/or a third 16-week, double-blind treatment at the other doses. Weights of patients were measured every week. During the first clozapine treatment, weight gain varied across 3 baseline BMI categories (normal-weight patients [4.1 kg, P < 0.001], overweight patients [2.6 kg, P = 0.05], and obese patients [0.36 kg, not significant]) and according to dosing (600 mg/d [4.4 kg], 300 mg/d [2.6 kg], and 100 mg/d [1.3 kg]). Sex had no effect after controlling for baseline BMI and dose, but the African-American race had a strong significant effect despite the small number of African Americans (n = 6). At the end of the first clozapine treatment, plasma norclozapine concentration was not significantly correlated with weight gain in the total sample (r = 0.16, P = 0.32, n = 43), but seems to be strongly correlated in nonsmokers. Despite its limitations, this study indicates that baseline BMI, dosing, and, possibly, the African-American race may be major determinants of clozapine-induced weight gain.

Low cerebrospinal fluid transthyretin levels in depression: correlations with suicidal ideation and low serotonin function

BACKGROUND

Transthyretin (TTR) is a thyroid hormone binding protein synthesized by choroid plexus and secreted into cerebrospinal fluid (CSF). We sought to replicate and extend our previous findings of lower CSF TTR in depression.

METHODS

Cerebrospinal fluid TTR concentrations of 17 medication-free patients with major depressive disorder (MDD) and 15 healthy individuals were determined by a sensitive, specific radioimmunoassay newly developed in our laboratory (ESL, TBC).

RESULTS

Cerebrospinal fluid TTR was lower in the MDD patients compared with healthy volunteers (mean +/- SD, 19.7 +/- 1.6 vs. 21.8 +/- 2.2 mg/L, p = .005). Age correlated positively with CSF TTR (r = .38, p < .05). The group difference remained significant (p < .005) after covariance for age. Within the MDD group, Scale for Suicide Ideation total score correlated inversely with CSF TTR (beta = -.58, p < .05). In the entire sample of depressed and healthy individuals, CSF 5-hydroxyindoleacetic acid (5-HIAA) correlated positively (beta = .34, p < .05) with CSF TTR.

CONCLUSIONS

We replicated our finding of low CSF TTR levels in depression and newly identified two relationships that may explain reports linking thyroid axis dysfunction and suicidal behaviors. Serotonergic hypofunction in depression, reflected by low CSF 5-HIAA, may result in decreased choroid plexus TTR production, alterations in central thyroid hormone kinetics, and increased vulnerability to suicidal ideation and perhaps suicide.

Modified dexamethasone suppression-corticotropin-releasing hormone stimulation test: A pilot study of young healthy volunteers and implications for alcoholism research in adolescents and young adults

The key neuroendocrine component of a response to stress is the hypothalamic-pituitary-adrenocortical (HPA) system. Abnormalities in the HPA system have been implicated in the pathophysiology of psychiatric disorders such as depression, post-traumatic stress disorder, alcoholism and suicide. The dexamethasone suppression test (DST) is the most frequently used test to assess HPA-system function in psychiatric disorders. This neuroendocrine test consists of the administration of a low dose of dexamethasone at 11 pm and the measurement of cortisol levels at one or more time points on the following day. After corticotropin-releasing hormone (CRH) became available for clinical studies, the DST was combined with CRH administration. In this test, patients are pretreated with a single dose of dexamethasone at 11 pm and receive human CRH intravenously at 3 pm the following day. The resulting DST-CRH test proved to be much more sensitive in detecting HPA system alterations than the DST. We have modified the DST-CRH test and used ovine CRH instead of human CRH in a pilot study of a group of young healthy volunteers. Results indicated that it produces results similar to the results obtained with human CRH. This suggests that ovine CRH can be used in psychiatric research. Alcoholism is associated with abnormalities in HPA function. Nonalcoholic subjects with a family history of alcoholism exhibit lower plasma ACTH and beta-endorphin as well as lower ACTH, cortisol, and beta-endorphin responses to psychological stress and CRH stimulation. This suggests that in children of alcoholics, alterations in the mechanisms that regulate HPA axis activity predate the development of alcohol dependence and may be considered inherited traits. Therefore, studies of the HPA system in persons at risk for alcoholism may help understand the neurobiological mechanisms of predisposition to alcoholism.

Effect of chronic ethanol exposure and its withdrawal on the endocannabinoid system

The present study investigated the effect of ethanol (EtOH) exposure and its withdrawal on the central endocannabinoid system utilizing an EtOH vapor inhalation model, which is known to produce functional tolerance and dependence to EtOH. Swiss Webster mice (n=24) were exposed to EtOH vapors for 72h. Mice were sacrificed after 72h following EtOH exposure (n=12) and 24h after its withdrawal (n=12). Radioligand binding assays were performed to measure the density of CB(1) receptor and CB(1) receptor agonist-stimulated [(35)S]GTPgammaS binding in crude synaptic membranes isolated from the cortex, hippocampus, striatum and cerebellum. The density of CB(1) receptor was significantly decreased (31-39%) in all the brain regions when compared to the control group. The CB(1) receptor-stimulated G(i/o) protein activation was also found to be decreased (29-40%) in these brain regions of EtOH exposed mice. Recovery of the CB(1) receptor density, in addition to, the CB(1) receptor-mediated G-protein activation was observed after 24h withdrawal from EtOH. The levels of cortical anandamide, which was significantly increased (147%) by EtOH exposure, returned to basal levels after 24h of withdrawal from EtOH exposure. A significant reduction (21%) in the activity of fatty acid amide hydrolase was found in the cortex of EtOH administered mice. Taken together, the neuroadaptation in the EC system may have a potential role in development of tolerance and dependence to EtOH.

Atypical antipsychotic agents in the treatment of violent patients with schizophrenia and schizoaffective disorder

CONTEXT

Violent behavior of patients with schizophrenia prolongs hospital stay and interferes with their integration into the community. Finding appropriate treatment of violent behaviors is of primary importance.

OBJECTIVE

To compare the efficacy of 2 atypical antipsychotic agents, clozapine and olanzapine, with one another and with haloperidol in the treatment of physical assaults and other aggressive behaviors in physically assaultive patients with schizophrenia and schizoaffective disorder.

DESIGN AND SETTING

Randomized, double-blind, parallel-group, 12-week trial. Physically assaultive subjects with schizophrenia or schizoaffective disorder who were inpatients in state psychiatric facilities were randomly assigned to treatment with clozapine (n = 37), olanzapine (n = 37), or haloperidol (n = 36).

MAIN OUTCOME MEASURES

Number and severity of physical assaults as measured by the Modified Overt Aggression Scale (MOAS) physical aggression score and the number and severity of all aggressive events as measured by the MOAS overall score. Psychiatric symptoms were assessed through the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Clozapine was superior to both olanzapine and haloperidol in reducing the number and severity of physical assaults as assessed by the MOAS physical aggression score and in reducing overall aggression as measured by the MOAS total score. Olanzapine was superior to haloperidol in reducing the number and severity of aggressive incidents on these 2 MOAS measures. There were no significant differences among the 3 medication groups in improvement of psychiatric symptoms as measured by the PANSS total score and the 3 PANSS subscales.

CONCLUSIONS

Clozapine shows greater efficacy than olanzapine and olanzapine greater efficacy than haloperidol in reducing aggressive behavior. This antiaggressive effect appears to be separate from the antipsychotic and sedative action of these medications.

The Effect of Mifepristone (RU 486) on Plasma Cortisol in Alzheimer’s Disease

The glucocorticoid receptor (GR) antagonist mifepristone (RU-486) has been reported to increase early morning plasma ACTH/cortisol in diverse non-demented populations. This pilot study examined the cortisol response to RU 486 in patients with Alzheimer's disease (AD), a condition associated with abnormalities in various aspects of the hypothalamic-pituitary-adrenal (HPA) axis. Nine AD subjects were randomized in a placebo-controlled parallel study: 4 in the placebo group and 5 in the RU 486 group. Subjects received oral doses of RU 486 (200 mg) or placebo daily for 6-weeks. Morning plasma cortisol was determined at baseline, at 12 h following the first study drug dose, and weekly thereafter. RU 486 resulted in a significant increase in cortisol levels [F(1,6)=65.32; P<0.001]. The magnitude of this increase grew over the course of the study [F(1,6)=63.17; P<0.001], was not related to cortisol suppression after dexamethasone and appeared greater than that reported in the literature in younger populations in response to the same drug regimen. However, further studies with age-matched controls should be done to determine possible AD related changes in this response.

Acute occupancy of brain serotonin transporter by sertraline as measured by [11C]DASB and positron emission tomography

BACKGROUND

In vivo determination of serotonin transporter (5-HTT) occupancy by selective serotonin reuptake inhibitors (SSRI) using positron emission tomography (PET) can aid in determination of dosing. Previous studies used chronic SSRI administration that may down-regulate 5-HTT and used the cerebellum as reference region despite measurable 5-HTT. We examine the reference region and occupancy after acute sertraline dosing.

METHODS

We conducted autoradiography of human postmortem cerebellum to determine an optimal reference region. We quantified 5-HTT binding using [(11)C]DASB and arterial input functions in 17 healthy volunteers. Baseline PET scans were followed by a scan 4-6 days after 25 mg to 100mg of daily sertraline. Several modeling methods and outcome measures were assessed.

RESULTS

Cerebellar gray matter is the optimal reference region. Occupation of 5-HTT sites saturates at low plasma sertraline levels (K(D) = 1.9 ng/ml) with maximal occupancies of 106.8 +/- 8.3% across all brain regions. There is a weak correlation between oral sertraline and plasma sertraline. Occupancy measures vary based on the reference region and outcome measure used.

CONCLUSIONS

Occupancy studies and postmortem autoradiography can help define the optimal reference region. Reference tissue modeling using the optimal reference region returns the same occupancy measures as those determined using an arterial input function.