Jennifer C. Naylor

Proof-of-Concept Trial with the Neurosteroid Pregnenolone Targeting Cognitive and Negative Symptoms in Schizophrenia

The neurosteroid pregnenolone and its sulfated derivative enhance learning and memory in rodents. Pregnenolone sulfate also positively modulates NMDA receptors and could thus ameliorate hypothesized NMDA receptor hypofunction in schizophrenia. Furthermore, clozapine increases pregnenolone in rodent hippocampus, possibly contributing to its superior efficacy. We therefore investigated adjunctive pregnenolone for cognitive and negative symptoms in patients with schizophrenia or schizoaffective disorder receiving stable doses of second-generation antipsychotics in a pilot randomized, placebo-controlled, double-blind trial. Following a 2-week single-blind placebo lead-in, patients were randomized to pregnenolone (fixed escalating doses to 500 mg/day) or placebo, for 8 weeks. Primary end points were changes in BACS and MCCB composite and total SANS scores. Of 21 patients randomized, 18 completed at least 4 weeks of treatment (n=9/group). Pregnenolone was well tolerated. Patients receiving pregnenolone demonstrated significantly greater improvements in SANS scores (mean change=10.38) compared with patients receiving placebo (mean change=2.33), p=0.048. Mean composite changes in BACS and MCCB scores were not significantly different in patients randomized to pregnenolone compared with placebo. However, serum pregnenolone increases predicted BACS composite scores at 8 weeks in the pregnenolone group (rs=0.81, p=0.022). Increases in allopregnanolone, a GABAergic pregnenolone metabolite, also predicted BACS composite scores (rs=0.74, p=0.046). In addition, baseline pregnenolone (rs=−0.76, p=0.037), pregnenolone sulfate (rs=−0.83, p=0.015), and allopregnanolone levels (rs=−0.83, p=0.015) were inversely correlated with improvements in MCCB composite scores, further supporting a possible role for neurosteroids in cognition. Mean BACS and MCCB composite scores were correlated (rs=0.74, p<0.0001). Pregnenolone may be a promising therapeutic agent for negative symptoms and merits further investigation for cognitive symptoms in schizophrenia.

Pregnenolone as a novel therapeutic candidate in schizophrenia: emerging preclinical and clinical evidence

Emerging preclinical and clinical evidence suggests that pregnenolone may be a promising novel therapeutic candidate in schizophrenia. Pregnenolone is a neurosteroid with pleiotropic actions in rodents that include the enhancement of learning and memory, neuritic outgrowth, and myelination. Further, pregnenolone administration results in elevations in downstream neurosteroids such as allopregnanolone, a molecule with neuroprotective effects that also increases neurogenesis, decreases apoptosis and inflammation, modulates the hypothalamic-pituitary-adrenal axis, and markedly increases GABA(A) receptor responses. In addition, pregnenolone administration elevates pregnenolone sulfate, a neurosteroid that positively modulates NMDA receptors. There are thus multiple mechanistic possibilities for pregnenolone as a potential therapeutic agent in schizophrenia, including the amelioration of NMDA receptor hypofunction (via metabolism to pregnenolone sulfate) and the mitigation of GABA dysregulation (via metabolism to allopregnanolone). Additional evidence consistent with a therapeutic role for pregnenolone in schizophrenia includes neurosteroid changes following administration of certain antipsychotics in rodent models. For example, clozapine elevates pregnenolone levels in rat hippocampus, and these increases may potentially contribute to its superior antipsychotic efficacy [Marx et al. (2006a) Pharmacol Biochem Behav 84:598-608]. Further, pregnenolone levels appear to be altered in postmortem brain tissue from patients with schizophrenia compared to control subjects [Marx et al. (2006c) Neuropsychopharmacology 31:1249-1263], suggesting that neurosteroid changes may play a role in the neurobiology of this disorder and/or its treatment. Although clinical trial data utilizing pregnenolone as a therapeutic agent in schizophrenia are currently limited, initial findings are encouraging. Treatment with adjunctive pregnenolone significantly decreased negative symptoms in patients with schizophrenia or schizoaffective disorder in a pilot proof-of-concept randomized controlled trial, and elevations in pregnenolone and allopregnanolone post-treatment with this intervention were correlated with cognitive improvements [Marx et al. (2009) Neuropsychopharmacology 34:1885-1903]. Another pilot randomized controlled trial recently presented at a scientific meeting demonstrated significant improvements in negative symptoms, verbal memory, and attention following treatment with adjunctive pregnenolone, in addition to enduring effects in a small subset of patients receiving pregnenolone longer-term [Savitz (2010) Society of Biological Psychiatry Annual Meeting New Orleans, LA]. A third pilot clinical trial reported significantly decreased positive symptoms and extrapyramidal side effects following adjunctive pregnenolone, in addition to increased attention and working memory performance [Ritsner et al. (2010) J Clin Psychiatry 71:1351-1362]. Future efforts in larger cohorts will be required to investigate pregnenolone as a possible therapeutic candidate in schizophrenia, but early efforts are promising and merit further investigation. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain.

Cerebrospinal Fluid Dehydroepiandrosterone Levels Are Correlated with Brain Dehydroepiandrosterone Levels, Elevated in Alzheimer’s Disease, and Related to Neuropathological Disease Stage

OBJECTIVE It is currently unknown whether cerebrospinal fluid (CSF) neurosteroid levels are related to brain neurosteroid levels in humans. CSF and brain dehydroepiandrosterone (DHEA) levels are elevated in patients with Alzheimers disease (AD), but it is unclear whether CSF DHEA levels are correlated with brain DHEA levels within the same subject cohort. We therefore determined DHEA and pregnenolone levels in AD patients (n = 25) and cognitively intact control subjects (n = 16) in both CSF and temporal cortex. DESIGN DHEA and pregnenolone levels were determined by gas chromatography/mass spectrometry preceded by HPLC. Frozen CSF and temporal cortex specimens were provided by the Alzheimers Disease Research Center at Duke University Medical Center. Data were analyzed by Mann-Whitney U test statistic and Spearman correlational analyses. RESULTS CSF DHEA levels are positively correlated with temporal cortex DHEA levels (r = 0.59, P < 0.0001) and neuropathological disease stage (Braak and Braak) (r = 0.42, P = 0.007). CSF pregnenolone levels are also positively correlated with temporal cortex pregnenolone levels (r = 0.57, P < 0.0001) and tend to be correlated with neuropathological disease stage (Braak) (r = 0.30, P = 0.06). CSF DHEA levels are elevated (P = 0.032), and pregnenolone levels tend to be elevated (P = 0.10) in patients with AD, compared with cognitively intact control subjects. CONCLUSIONS These findings indicate that CSF DHEA and pregnenolone levels are correlated with temporal cortex brain levels of these neurosteroids and that CSF DHEA is elevated in AD and related to neuropathological disease stage. Neurosteroids may thus be relevant to the pathophysiology of AD.

Allopregnanolone levels are reduced in temporal cortex in patients with Alzheimer's disease compared to cognitively intact control subjects.

The neurosteroid allopregnanolone has pronounced neuroprotective actions, increases myelination, and enhances neurogenesis. Evidence suggests that allopregnanolone dysregulation may play a role in the pathophysiology of Alzheimers disease (AD) and other neurodegenerative disorders. Our prior data demonstrate that allopregnanolone is reduced in prefrontal cortex in male patients with AD compared to male cognitively intact control subjects, and inversely correlated with neuropathological disease stage (Braak and Braak). We therefore determined if allopregnanolone levels are also reduced in AD patients compared to control subjects in temporal cortex, utilizing a larger set of samples from both male and female patients. In addition, we investigated if neurosteroids are altered in subjects who are APOE4 allele carriers. Allopregnanolone, dehydroepiandrosterone (DHEA), and pregnenolone levels were determined in temporal cortex postmortem samples by gas chromatography/mass spectrometry, preceded by high performance liquid chromatography (40 subjects with AD/41 cognitively intact control subjects). Allopregnanolone levels are reduced in temporal cortex in patients with AD (median 2.68 ng/g, n=40) compared to control subjects (median 5.64 ng/g, n=41), Mann-Whitney p=0.0002, and inversely correlated with Braak and Braak neuropathological disease stage (Spearman r=-0.38, p=0.0004). DHEA and pregnenolone are increased in patients with AD compared to control subjects. Patients carrying an APOE4 allele demonstrate reduced allopregnanolone levels in temporal cortex (Mann-Whitney p=0.04). In summary, our findings indicate that neurosteroids are altered in temporal cortex in patients with AD and related to neuropathological disease stage. In addition, the APOE4 allele is associated with reduced allopregnanolone levels. Neurosteroids may be relevant to the neurobiology and therapeutics of AD.

Neurosteroids and Self-Reported Pain in Veterans Who Served in the U.S. Military after September 11, 2001

OBJECTIVE Nearly half of Operation Enduring Freedom/Operation Iraqi Freedom veterans experience continued pain post-deployment. Several investigations report analgesic effects of allopregnanolone and other neurosteroids in animal models, but few data are currently available focusing on neurosteroids in clinical populations. Allopregnanolone positively modulates GABA(A) receptors and demonstrates pronounced analgesic and anxiolytic effects in rodents, yet studies examining the relationship between pain and allopregnanolone in humans are limited. We thus hypothesized that endogenous allopregnanolone and other neurosteroid levels may be negatively correlated with self-reported pain symptoms in humans. DESIGN We determined serum neurosteroid levels by gas chromatography/mass spectrometry (allopregnanolone, pregnenolone) or radioimmunoassay (dehydroepiandrosterone [DHEA], progesterone, DHEA sulfate [DHEAS]) in 90 male veterans who served in the U.S. military after September 11, 2001. Self-reported pain symptoms were assessed in four areas (low back pain, chest pain, muscle soreness, headache). Stepwise linear regression analyses were conducted to investigate the relationship between pain assessments and neurosteroids, with the inclusion of smoking, alcohol use, age, and history of traumatic brain injury as covariates. SETTING Durham VA Medical Center. RESULTS Allopregnanolone levels were inversely associated with low back pain (P=0.044) and chest pain (P=0.013), and DHEA levels were inversely associated with muscle soreness (P=0.024). DHEAS levels were positively associated with chest pain (P=0.001). Additionally, there was a positive association between traumatic brain injury and muscle soreness (P=0.002). CONCLUSIONS Neurosteroids may be relevant to the pathophysiology of self-reported pain symptoms in this veteran cohort, and could represent future pharmacological targets for pain disorders.

A pilot randomized controlled trial with paroxetine for subthreshold PTSD in Operation Enduring Freedom/Operation Iraqi Freedom era veterans.

Subthreshold posttraumatic stress disorder (PTSD) is associated with increased risk for suicidality, depression, and functional impairment. We thus conducted a small (N=12) pilot randomized controlled trial (RCT) with paroxetine for subthreshold PTSD in Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) era veterans. Hospital Anxiety and Depression Scale (HADS) scores improved by 30.4% in the paroxetine group. Paroxetine may have promise for subthreshold PTSD.

A pilot randomized placebo-controlled trial of adjunctive aripiprazole for chronic PTSD in US military Veterans resistant to antidepressant treatment.

Many individuals with post-traumatic stress disorder (PTSD) experience persistent symptoms despite pharmacological treatment with antidepressants. Several open-label monotherapy and adjunctive studies have suggested that aripiprazole (a second-generation antipsychotic) may have clinical utility in PTSD. However, there have been no randomized placebo-controlled trials of aripiprazole use for PTSD. We thus conducted a pilot randomized controlled trial of adjunctive aripiprazole versus placebo among Veterans with chronic PTSD serving in the US military since 11 September 2001 to assess the feasibility, safety, tolerability, and therapeutic potential of aripiprazole. Sixteen Veterans were randomized, and 14 completed at least 4 weeks of the study; 12 completed the entire 8-week trial. Outcome measures included the Clinician-Administered PTSD Scale (CAPS), PTSD Checklist, Beck Depression Inventory, Second Edition, and Positive and Negative Syndrome Scale scores. Aripiprazole was well-tolerated in this cohort, and improvements in CAPS, PTSD Checklist, Beck Depression Inventory, Second Edition, and Positive and Negative Syndrome Scale scores were as hypothesized. Although CAPS change scores did not reach statistical significance, aripiprazole outperformed placebo by 9 points on the CAPS in the last observation carried forward analysis compared with the placebo group (n=7 per group), and by 20 points in the group randomized to aripiprazole that completed the entire study (n=5) compared with the placebo group (n=7). Results suggest promise for aripiprazole as an adjunctive strategy for the treatment of PTSD.

No association between RORA polymorphisms and PTSD in two independent samples

Logue et al.1 reported genome-wide significant association between a polymorphism (rs8042149) in the RORA gene, encoding the retinoic acid orphan receptor A, and posttraumatic stress disorder (PTSD) in a cohort of trauma-exposed white non-Hispanic US veterans and their partners. The genome-wide association study yielded evidence of association for three additional SNPs at the 10-6 threshold in the same cohort (rs8041061, rs8024133, rs11071561). Amstadter et al.2 reported a significant association between rs8042149 and PTSD symptoms in the 2004 Florida Hurricane Study. The RORA gene encodes a nuclear hormone receptor that regulates the transcription activity of nearby genes. It is widely expressed in the brain, where it protects cortical neurons against oxidative stress-induced apoptosis by increasing the expression of antioxidant proteins.1 Logue et al.1 proposed that genetic variations in RORA may alter its expression, reducing the capacity of neurons to respond to biochemical stressors induced by traumatic stress.

Cathodal and anodal left prefrontal tDCS and the perception of control over pain.

Objectives:The prefrontal cortex may be a promising target for the use of transcranial direct current stimulation (tDCS) in the management of pain symptoms. The present study explored the effects of anodal and cathodal tDCS over the left dorsolateral prefrontal cortex on the effects of perceived pain controllability. Materials and Methods:Forty-one participants received continuous anodal or cathodal tDCS and underwent a laboratory pain task designed to manipulate the perception of pain control. Participants were told that they would be completing a reaction-time task (press keyboard button of corresponding arrow shown on computer screen with either green or red background). A thermal pain stimulus was delivered following each trial by a thermode placed on the participant’s left forearm. Although pain stimuli were pseudorandomally ordered and matched for total duration between control (green) and noncontrol (red) trials, participants were told that if they responded correctly and more quickly on green trials than their average reaction times, the thermal pain stimulus duration would be decreased (ie, perceived control). Participants were told they had no control of pain stimulus duration over trials presented with the red background. Results:There was a significant main effect for tDCS condition (anode vs. cathode) on pain unpleasantness ratings (P<0.04). Specifically, individuals receiving cathodal tDCS reported higher pain unpleasantness ratings (least squares mean=69.40, SE=3.72), whereas those receiving anodal tDCS reported lower pain unpleasantness ratings (least squares mean=58.05, SE=3.81). Exploratory analysis revealed a simple main effect for tDCS group at the level of perceived controllability (P<0.02). In addition, participants receiving cathodal tDCS subjectively reported feeling less control of the painful stimuli than those receiving anodal tDCS. Discussion:Left dorsolateral prefrontal cortex tDCS may play a role in modulating the neurocircuitry involved with the perception of control over pain.

An open-label pilot study of aripiprazole for male and female veterans with chronic post-traumatic stress disorder who respond suboptimally to antidepressants.

Emerging data suggest that second-generation antipsychotics such as aripiprazole may be effective in the treatment of post-traumatic stress disorder (PTSD). However, few clinical trials have used aripiprazole in PTSD, and data are limited on its use in Veterans with PTSD. The objective of this pilot trial was to investigate the safety and efficacy of aripiprazole in Veterans with PTSD. Ten individuals (five men and five women) meeting the Diagnostic and statistical manual of mental disorders, 4th ed., PTSD criteria participated in this 12-week, open-label, flexibly dosed monotherapy trial. The dose range of aripiprazole was 5–30 mg/day, titrated to tolerability and clinical response. The primary outcome measure was the Clinician-Administered PTSD Scale. Additional outcomes included the Short PTSD Rating Interview, the Treatment Outcome PTSD Scale (Top-8), the Davidson Trauma Scale, the Positive and Negative Syndrome Scale, the Beck Depression Inventory-Fast Screen, and Clinical Global Impressions-Improvement. Eight participants completed the study, and aripiprazole was generally well tolerated and associated with a significant improvement in PTSD symptoms, as measured by the Clinician-Administered PTSD Scale (primary outcome measure) and by the Short PTSD Rating Interview, the Treatment Outcome PTSD Scale, and the Davidson Trauma Scale. An improvement was also observed on all three Positive and Negative Syndrome Scale subscales and the Beck Depression Inventory-Fast Screen, and the average Clinical Global Impressions-Improvement ratings indicated that patients were ‘much improved’. These promising initial results merit further investigation in a larger, randomized-controlled trial.