Electrical stimulation of the trigeminal nerve improves olfaction in healthy individuals: A randomized, double-blind, sham-controlled trial

BACKGROUND

Both activated by environmental odorants, there is a clear role for the intranasal trigeminal and olfactory nerves in smell function. Unfortunately, our ability to perceive odorants decreases with age or with injury, and limited interventions are available to treat smell loss.

OBJECTIVE

We investigated whether electrical stimulation of the trigeminal nerve via trigeminal nerve stimulation (TNS) or transcranial direct current stimulation (tDCS) modulates odor sensitivity in healthy individuals.

METHODS

We recruited 20 healthy adults (12 Female, mean age = 27) to participate in this three-visit, randomized, double-blind, sham-controlled trial. Participants were randomized to receive one of three stimulation modalities (TNS, tDCS, or sham) during each of their visits. Odor detection thresholds were obtained at baseline, immediately post-intervention, and 30-min post-intervention. Furthermore, participants were asked to complete a sustained attention task and mood assessments before odor detection testing.

RESULTS

Findings reveal a timeXcondition interaction for guaiacol (GUA) odorant detection thresholds (F (3.188, 60.57) = 3.833, P = 0.0125), but not phenyl ethyl alcohol (PEA) odorant thresholds. At 30-min post-stimulation, both active TNS and active tDCS showed significantly increased sensitivity to GUA compared to sham TNS (Sham TNS = -8.30% vs. Active TNS = 9.11%, mean difference 17.43%, 95% CI 5.674 to 29.18, p = 0.0044; Sham TNS = -8.30% vs. Active tDCS = 13.58%, mean difference 21.89%, 95% CI 10.47 to 33.32, p = 0.0004).

CONCLUSION

TNS is a safe, simple, noninvasive method for boosting olfaction. Future studies should investigate the use of TNS on smell function across different stimulation parameters, odorants, and patient populations.

Anxiety-related shifts in smell function in children and adolescents

Anxious adults show changes in smell function that are consistent with a durable shift in sensitivity toward particular odorants and away from others. Little is known regarding the development of these changes, including whether they exist in youth, are stable during the transition from childhood to adolescence, and whether odorant properties (e.g. trigeminal features, hedonic valence) affect anxiety-related differences in detection. To address this, we measured smell detection thresholds to phenyl ethyl alanine (PEA), a rose-like odorant with little trigeminal properties, and guaiacol (GUA), a smoke-like odorant with high trigeminal properties. These thresholds were measured at baseline and after an acute stress challenge, the Trier Social Stress Tests, in 131 healthy youth (in 4th, 7th, and 10th grades, age 9-16 years) that reported normal to elevated levels of anxiety. At baseline, high anxious youth exhibited heightened sensitivity to GUA coupled with reduced sensitivity to PEA, as well as a further exaggeration of this bias with acute stress. Importantly, sex, age, and hedonic valence moderated the relationship between trait anxiety and sensitivity to both odorants. Smell function and its aberrations are often overlooked in the literature on biomarkers of stress and anxiety. Taken together with the extant literature, these findings suggest that greater attention is warranted to characterize potential novel olfactory therapeutic targets-across the lifespan.

Exploratory Investigation of a Brief Cognitive Behavioral Intervention and Transcranial Direct Current Stimulation on Odor Sensitivity

OBJECTIVE

Enhanced odor sensitivity is a phenomenon that potentially underlies conditions such as multiple chemical sensitivity (MCS). Currently, there are no treatments that have been shown to effectively decrease odor sensitivity. Given similarities of odor hypersensitivity/MCS to pain sensitization disorders such as fibromyalgia, there may be a potential for interventions that improve pain tolerance to modulate odor sensitivity.

METHODS

This exploratory study randomized 72 healthy community adult volunteers to receive one of six treatments in between two assessments of thermal pain tolerance and odor threshold. Participants were randomized to receive either cathodal, anodal, or sham transcranial direct current stimulation (tDCS) aimed at dorsolateral prefrontal cortex. In addition, participants were provided a brief cognitive behavioral intervention (CBI) for pain consisting of task framing, cognitive restructuring, and distraction technique training, or a control intervention consisting of information about pain.

RESULTS

Persons who received a brief CBI showed significantly increased odor thresholds (reduced sensitivity) during intervention (F (1,62) = 7.29, p = .009, ηp = .11), whereas the control intervention was not associated with altered odor thresholds. Moreover, in those who received brief CBI, more severe anxiety associated with larger reductions in odor sensitivity (ρ = .364, p = .035). There was no effect of tDCS (F (2,62) = .11, p = .90) nor interaction between tDCS and CBI (F (2,62) = .32, p = .73).

CONCLUSIONS

Given the connection between anxiety and MCS, results suggest that CBT techniques for somatic processes may show promise in treating conditions characterized by increased sensitivity to odors (e.g., MCS).

Paradoxical olfactory function in combat veterans: The role of PTSD and odor factors

Stress- and trauma-related disorders, including posttraumatic stress disorder (PTSD), are characterized by an increased sensitivity to threat cues. Given that threat detection is a critical function of olfaction and that combat trauma is commonly associated with burning odors, we sought a better understanding of general olfactory function as well as response to specific trauma-related (i.e. burning) odors in combat-related PTSD. Trauma-exposed combat veterans with (N = 22) and without (N = 25) PTSD were assessed for general and specific odor sensitivities using a variety of tools. Both groups had similar general odor detection thresholds. However, the combat veterans with PTSD, compared to combat veterans with comparable trauma exposure, but without PTSD, had increased ratings of odor intensity, negative valence, and odor-triggered PTSD symptoms, along with a blunted heart rate in response to burning rubber odor. These findings are discussed within the context of healthy versus pathological changes in olfactory processing that occur over time after psychological trauma.

Preliminary evidence for differential olfactory and trigeminal processing in combat veterans with and without PTSD

Structural and functional changes in the olfactory system are increasingly implicated in the expression of PTSD. Still, very little is known about the neurobiological networks of trauma-related odor sensitivity or how they relate to other objective and subjective measures of olfaction and PTSD. The purpose of this study was to replicate prior findings and further characterize olfactory function in trauma-exposed combat veterans with and without PTSD. We also sought to extend this area of research by exploring the effects of time since the combat-related index trauma (TST) on post-trauma olfactory function, as well as by correlating odor-elicited brain activity to general olfactory ability and odor-elicited PTSD symptoms. Participants included combat veterans with PTSD (CV+PTSD; n = 21) or without any psychiatric disorder (CV-PTSD; n = 27). TST was coded as greater (n = 24) or less (n = 24) than 5 years. There were main effects and/or interaction for PTSD-status and TST across several parameters of olfactory function: odor detection, odor identification, ratings for trauma-related odor intensity and triggered PTSD symptoms, and trauma odor-elicited brain activation. Overall, results suggest olfactory impairment in chronic PTSD, but not necessarily in the earlier stages of the disorder, although some early-stage olfactory findings may be predictive of later olfactory impairment. Results also suggest that trauma-exposed individuals who never develop PTSD may demonstrate olfactory resiliency. Finally, results highlight a potentially unique role of trigeminal odor properties in the olfactory-PTSD relationship.

Depression in chronic rhinosinusitis: A controlled cohort study

BACKGROUND

Depression in patients with chronic rhinosinusitis (CRS) is underdiagnosed but significantly impacts treatment outcomes and health care utilization.

OBJECTIVE

To compare undiagnosed depression in a CRS cohort with a healthy, non-CRS control cohort.

METHODS

A case-control study of patients with symptomatic CRS and a non-CRS control cohort was performed. Demographic and comorbidity factors were correlated to depression-specific outcomes by using the Beck Depression Inventory II (BDI).

RESULTS

We enrolled 42 patients with CRS and 88 control patients with no history of CRS. Physician-diagnosed depression was equivalent in CRS and control patients (6% and 9%, respectively). BDI-detected depression was higher among patients with CRS compared with controls (31% versus 14.8%, respectively; p = 0.031). BDI scores were higher in patients with CRS even when controlling for comorbid asthma, allergy, and aspirin sensitivity. When examined by polyp status, the patients without polyps had more depression than did the controls (38% versus 14.8%; p = 0.048). The somatic subscale scores of the BDI were worse in patients with CRS (p = 0.004), whereas the cognitive subscale trended toward significance (p = 0.081).

CONCLUSION

Depression may be more common in CRS than previously recognized, especially in patients without polyps. Somatic subscale scores of the BDI are increased in CRS and may impact future treatment outcomes.

Depression-Specific Outcomes After Treatment of Chronic Rhinosinusitis

IMPORTANCE

Depression is frequently undiagnosed in patients with chronic rhinosinusitis (CRS) and affects quality of life, productivity, and health care use.

OBJECTIVE

To examine depression-specific outcomes after medical or surgical treatment of CRS.

DESIGN, SETTING, AND PARTICIPANTS

A multi-institutional, prospective study of patients with refractory CRS treated at tertiary academic rhinology centers was performed from March 1, 2011, to November 1, 2015. Data analysis was performed from October 1, 2015, to November 1, 2015.

INTERVENTIONS

Patients self-selected to undergo continued medical management or endoscopic sinus surgery for refractory CRS.

MAIN OUTCOMES AND MEASURES

Patients completed the 22-item Sinonasal Outcome Test (SNOT22), Rhinosinusitis Disability Index (RSDI), Pittsburgh Sleep Quality Index (PSQI), and missed productivity and medication use questionnaires before and at least 6 months after treatment. Computed tomography and endoscopy scoring were performed with reviewers masked to patient-reported data. Depression-specific outcomes were recorded using the 2-item Patient Health Questionnaire (PHQ2).

RESULTS

Baseline data were available on 685 patients, with 167 (24.4%) having depression according to the PHQ2 scores. The mean (SD) age of the patients was 50.5 (15.0) years, and 332 (48.4%) were male. Revision surgery status was the only baseline factor associated with depression (53.9% vs 38.0%, P < .001). Patients with depression had worse baseline SNOT22 (mean, 64.5 vs 47.6), PSQI (mean, 12.8 vs 8.4), productivity (mean, 22.8 vs 5.2 days missed), and medication use scores for oral antibiotics (mean, 23.8 vs 14.8) and oral corticosteroids (mean, 17.8 vs 9.9) (P < .001 for all). Medical and surgical treatments had similar outcomes for patients with depression with mean improvement in the PHQ2 scores from 3.96 to 1.91 (P < .001), and 110 of 167 patients (65.9%) categorized as having depression at baseline were categorized as not having depression after treatment. Improvements in the PHQ2 scores were associated with improvements in the SNOT22, PSQI, oral antibiotic use, and productivity scores (P ≤ .001 for all).

CONCLUSIONS AND RELEVANCE

Depression is a common comorbidity in patients with CRS and affects numerous quality-of-life and health care outcomes. There are few objective baseline factors to aid physicians in identifying depression in patients with CRS. Medical and surgical treatments for CRS improve depression and related clinical outcomes.

The fMRI BOLD response to unisensory and multisensory smoking cues in nicotine-dependent adults

Given that the vast majority of functional magnetic resonance imaging (fMRI) studies of drug cue reactivity use unisensory visual cues, but that multisensory cues may elicit greater craving-related brain responses, the current study sought to compare the fMRI BOLD response to unisensory visual and multisensory, visual plus odor, smoking cues in 17 nicotine-dependent adult cigarette smokers. Brain activation to smoking-related, compared to neutral, pictures was assessed under cigarette smoke and odorless odor conditions. While smoking pictures elicited a pattern of activation consistent with the addiction literature, the multisensory (odor+picture) smoking cues elicited significantly greater and more widespread activation in mainly frontal and temporal regions. BOLD signal elicited by the multisensory, but not unisensory cues, was significantly related to participants' level of control over craving as well. Results demonstrated that the co-presentation of cigarette smoke odor with smoking-related visual cues, compared to the visual cues alone, elicited greater levels of craving-related brain activation in key regions implicated in reward. These preliminary findings support future research aimed at a better understanding of multisensory integration of drug cues and craving.

Differential odor sensitivity in PTSD: Implications for treatment and future research

BACKGROUND

Given that odors enhance the retrieval of autobiographical memories, induce physiological arousal, and trigger trauma-related flashbacks, it is reasonable to hypothesize that odors play a significant role in the pathophysiology of posttraumatic stress disorder (PTSD). For these reasons, this preliminary study sought to examine self-reported, odor-elicited distress in PTSD.

METHODS

Combat veterans with (N=30) and without (N=22) PTSD and healthy controls (HC: N=21), completed an olfactory questionnaire that provided information on the hedonic valence of odors as well as their ability to elicit distress or relaxation.

RESULTS

Two main findings were revealed: Compared to HC, CV+PTSD, but not CV-PTSD, reported a higher prevalence of distress to a limited number of select odors that included fuel (p=.004), blood (p=.02), gunpowder (p=.03), and burning hair (p=.02). In contrast to this increased sensitivity, a blunting effect was reported by both groups of veterans compared to HC that revealed lower rates of distress and relaxation in response to negative hedonic odors (p=.03) and positive hedonic odors (p<.001), respectively.

LIMITATIONS

The study is limited by its use of retrospective survey methods, whereas future investigations would benefit from laboratory measures taken prior, during, and after deployment.

CONCLUSION

The present findings suggest a complex role of olfaction in the biological functions of threat detection. Several theoretical models are discussed. One possible explanation for increased sensitivity to select odors with decreased sensitivity to other odors is the co-occurrence of attentional bias toward threat odors with selective ignoring of distractor odors. Working together, these processes may optimize survival.

Olfactory cue reactivity in nicotine-dependent adult smokers

Cue-elicited reactivity is a significant factor in relapse during smoking quit attempts. Previous research has focused primarily on visual smoking cues, with very limited research examining reactivity to olfactory triggers. Twenty-six adult non-treatment-seeking, nicotine-dependent smokers were exposed to 7 odorants during a cue-reactivity session measuring heart rate, skin conductance, and subjective craving. Cues included 2 cigarette odors (fresh tobacco and cigarette smoke), 2 odors previously identified as smoking-related (freshly mowed grass and coffee), 2 odors previously identified as unrelated to smoking (lavender and burned rubber), and 1 odorless control (propylene glycol). Pairwise comparisons demonstrated that subjective intensity of craving was significantly higher following exposure to the fresh tobacco odor compared with the odorless control (p < .01). A significant main effect for cue type on a physiological measure of arousal was also revealed, with a fresh tobacco odor-elicited significant increase in skin conductance level compared with the odorless control. However, no main effect of cue type on heart rate was found (p = .25). The results of the present study indicate that cigarette odor is an effective olfactory cue that heightens both subjective craving and increases skin conductance in smokers. Future research is needed to evaluate whether avoidance of these odors, or extinction of responses to them, can reduce relapse risk during smoking quit attempts.

Region-specific alteration in brain glutamate: possible relationship to risk-taking behavior

Risk-taking behaviors involve increased motor activity and reduced anxiety in humans. Total sleep deprivation (SD) in animals produces a similar change in motor and fear behaviors. Investigators studied region-specific brain levels of glutamate in rats after TSD, an animal model of risk-taking behavior. We investigated the effects of sleep deprivation on these behaviors and associated levels of brain glutamate. Compared to the controls, the sleep-deprived rats spent a significantly greater percentage of time in the open arms of the elevated plus maze (EPM), demonstrating reduced fear-like and increased risk-taking behaviors. Additionally, sleep deprivation was associated with a significant increase in glutamate levels in the hippocampus and thalamus. An inverse relationship between glutamate in the medial prefrontal cortex and risk taking in the EPM and a positive association between the ratio of glutamate in the hippocampus to medial prefrontal cortex and risk taking was revealed. The role of sleep deprivation-induced changes in brain glutamate and its relationship to anxiety, fear, and posttraumatic stress disorder (PTSD) is discussed.

Cataplexy in anxious patients: is subclinical narcolepsy underrecognized in anxiety disorders?

OBJECTIVE

Excessive daytime sleepiness, hypnagogic-hypnopompic hallucinations, sleep paralysis, and cataplexy are symptoms associated with narcolepsy. Recent findings indicate that anxiety disorders also are associated with excessive daytime sleepiness, hypnagogic-hypnopompic hallucinations, and sleep paralysis. These observations suggest a possible relationship between anxiety disorders and narcolepsy. Cataplexy is considered the most specific symptom of narcolepsy, but its association with anxiety disorders is unknown. This preliminary investigation examined the prevalence and types of cataplexy in patients with primary anxiety disorders.

METHOD

Sex- and age-matched patients with anxiety disorders (N = 33) and healthy volunteers (N = 33) were assessed on standardized and validated measures of subjective sleep quality (Pittsburgh Sleep Quality Index) and subclinical narcoleptic events in the form of cataplexy (Stanford Center for Narcolepsy Revised Sleep Inventory). Patients were recruited from October 2006 to January 2007 from 2 programs of the Penn State Behavioral Health Clinic.

RESULTS

Anxiety disorder patients as a group reported poorer sleep quality and endorsed a larger number of different types of situations (e.g., surprise, embarrassment) associated with cataplectic events. Among anxious patients, 33.3% (11 of 33) endorsed events specific for classic cataplexy, as opposed to 9.1% (3 of 33) of healthy volunteers (chi(2) = 5.80, p = .016).

CONCLUSIONS

Our preliminary findings suggest that anxiety disorders are associated with increased rates of cataplexy. Future research is indicated to elucidate the relationship between anxiety and narcolepsy, with a particular focus on panic and generalized anxiety disorders.

A longitudinal study of the effects of lithium treatment on prefrontal and subgenual prefrontal gray matter volume in treatment-responsive bipolar disorder patients

OBJECTIVE

Recent molecular, preclinical, and preliminary clinical studies suggest that the therapeutic effects of mood stabilizers may be mediated by modulating expression of potent neurotrophic and neuroprotective factors having the potential to reverse impairments of cellular resilience, reductions in brain volume, and cell death or atrophy. Our main goal was to investigate the potential clinical significance of these findings in relation to bipolar disorder.

METHOD

The longitudinal effect of lithium on brain gray matter volume was investigated in well-characterized (DSM-IV criteria) bipolar depressed subjects (N = 28) at baseline (medication-free) and after lithium administration (4 weeks). Total brain gray matter, prefrontal gray matter, and left subgenual prefrontal gray matter volumes were determined using validated semiautomated segmentation and region of interest methodology. The study was conducted from November 1997 until April 2004 at Wayne State University School of Medicine, Detroit, Mich.

RESULTS

Significant increases in total brain gray matter volume in bipolar subjects were observed after 4 weeks of lithium administration (p = .0043). Moreover, regional analyses in the bipolar subjects revealed significant differences between responders (>50% decrease in Hamilton Depression Rating Scale total score) and nonresponders; only responders showed a significant increase in gray matter volume in the prefrontal cortex (p = .003) and an increase at trend level in the left subgenual prefrontal cortex volume (p = .0786).

CONCLUSION

The increase in gray matter volume in these areas, which various neuroimaging and postmortem neuropathology studies have implicated in the neuropathophysiology of bipolar disorder, suggests that the observed effects may be linked to clinical response. The findings also support the notion that future treatments that more directly target molecules in critical central nervous system pathways that regulate cellular plasticity hold promise as novel, improved, long-term treatments for mood disorders as well as some neurodegenerative conditions, such as Alzheimer's disease.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00870311.

Examining lactate in severe TBI using proton magnetic resonance spectroscopy

PRIMARY OBJECTIVE

Clinical management of acute traumatic brain injury (TBI) has emphasized identification of secondary mechanisms of pathophysiology. An important objective in this study is to use proton magnetic resonance spectroscopy (pMRS) to examine early metabolic disturbance due to TBI.

RESEARCH DESIGN

The current design is a case study with repeated measures.

METHOD AND PROCEDURE

Proton magnetic resonance imaging was used to examine neurometabolism in this case of very severe brain trauma at 9 and 23 days post-injury. MRI was performed on a clinical 1.5 Tesla scanner.

MAIN OUTCOMES AND RESULTS

These data also reveal that pMRS methods can detect lactate elevations in an adult surviving severe head trauma and are sensitive to changes in basic neurometabolism during the first month of recovery.

CONCLUSIONS

The current case study demonstrates the sensitivity of pMRS in detecting metabolic alterations during the acute recovery period. The case study reveals that lactate elevations may be apparent for weeks after severe neurotrauma. Further work in this area should endeavour to determine the ideal time periods for pMRS examination in severe TBI as well as the ideal locations of data acquisition (e.g. adjacent or distal to lesion sites).

Magnetic resonance and spectroscopic imaging in prenatal alcohol-exposed children: preliminary findings in the caudate nucleus

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) offer unique, noninvasive methods of measuring, respectively, in vivo quantitative neuroanatomy and neurochemistry. The main purpose of the present study was to identify and compare the neuroanatomical and neurochemical abnormalities that are associated with prenatal exposure to alcohol in both fetal alcohol syndrome (FAS)-diagnosed children and those diagnosed with fetal alcohol effects (FAE). MR data of three age-, gender- and race-balanced groups of children, FAS-diagnosed, FAE-diagnosed and non-exposed controls, were compared. Effects of prenatal alcohol exposure, regardless of diagnosis, were found in the caudate nucleus. Specifically, a significantly smaller caudate nucleus was found for the FAS and FAE participants compared to the controls. In addition, the metabolite ratio of N-acetyl-aspartate to creatine (NAA/Cr), an indicator of neuronal function, in left caudate nucleus of both the FAS and FAE participants was elevated compared to the control group. Analysis of absolute concentrations revealed that the increase in the ratio of NAA/Cr was due to an increase in NAA alone. Although its exact function in the CNS is unknown, NAA is believed to be a neuronal marker due to its exclusive localization to neurons. Some also speculate a role for NAA in myelination. Elevated NAA in the prenatal alcohol-exposed participants could indicate a lack of normal program cell death, dendritic pruning and/or myelination during development. The present study demonstrates that prenatal alcohol-exposed children, with or without facial dysmorphology, have abnormal brain anatomy and chemistry.

The role of glutamate in anxiety and related disorders

Anxiety, stress, and trauma-related disorders are a major public health concern in the United States. Drugs that target the gamma-aminobutyric acid or serotonergic system, such as benzodiazepines and selective serotonin reuptake inhibitors, respectively, are the most widely prescribed treatments for these disorders. However, the role of glutamate in anxiety disorders is becoming more recognized with the belief that drugs that modulate glutamatergic function through either ionotropic or metabotropic glutamate receptors have the potential to improve the current treatment of these severe and disabling illnesses. Animal models of fear and anxiety have provided a method to study the role of glutamate in anxiety. This research has demonstrated that drugs that alter glutamate transmission have potential anxiolytic action for many different paradigms including fear-potentiated startle, punished responding, and the elevated plus maze. Human clinical drug trials have demonstrated the efficacy of glutamatergic drugs for the treatment of obsessive-compulsive disorder, posttraumatic stress disorder, generalized anxiety disorder, and social phobia. Recent data from magnetic resonance imaging studies provide an additional link between the glutamate system and anxiety. Collectively, the data suggest that future studies on the mechanism of and clinical efficacy of glutamatergic agents in anxiety disorders are appropriately warranted.

Anterior cingulate neurochemistry in social anxiety disorder: 1H-MRS at 4???Tesla

Recent studies suggest exaggerated responses in the limbic system of patients with generalized social anxiety disorder in response to threat/anxiety-related social situations and aversive conditioning, processes mediated by the glutamatergic system. This single-voxel, high-field 1H-magnetic resonance spectroscopy study examined concentrations of glutamate, and other metabolites, in the anterior cingulate cortex and occipital cortex (control region) of 10 medication-naive patients with generalized social anxiety and 10 matched healthy comparison subjects. Glutamate (relative to creatine) levels were significantly higher in patients than controls in the anterior cingulate, but not occipital, cortex. Anterior cingulate glutamate/creatine levels were also correlated with intensity of social anxiety symptoms. These findings provide new evidence of glutamate's involvement in the neural mechanism underlying social phobia.

Effects of prenatal ethanol exposure on hippocampal theta activity in the rat

This study examined the effects of prenatal ethanol exposure on hippocampal theta activity in adult rats. Subjects were randomly selected from four prenatal treatment conditions: untreated, 0, 3, or 5 g/kg/day ethanol. At approximately 90 days of age, all subjects were surgically implanted with a bipolar electrode in the CA1 region of the hippocampus. Four epochs of hippocampal theta rhythm activity were recorded while the subjects were moving and four more while still, and a normalized theta score was computed and compared among groups. The 5 g/kg male group demonstrated a significantly higher theta score than controls, indicating either an increase in type I (movement-associated) theta and/or a decrease in type II (information-processing) theta activity. These results are consistent with prior reports that prenatal ethanol exposure alters hippocampal function and support clinical indications that monitoring the EEG of children may prove to be useful in the diagnosis of fetal alcohol syndrome and/or the detection of alcohol-related birth defects.

Scopolamine does not differentially affect Morris maze performance in adult rats exposed prenatally to alcohol

Rats exposed prenatally to alcohol have shown deficits in spatial learning in radial-arm and Morris mazes. Prenatal exposure to alcohol in rats has also been shown to alter central nervous system (CNS) cholinergic function. Since cholinergic dysfunction disrupts spatial learning in normal rats, the present experiment assessed the role of putative prenatal alcohol-induced cholinergic dysfunction in spatial learning in rats. Pregnant rats were fed alcohol via liquid diet from gestation day 6 to 20. Control dams were pair-fed liquid diet without alcohol or fed ad lib lab chow and water. Group housed adult male and female offspring (postnatal days 110 to 135) were given scopolamine-HCl (0, 0.5, or 1.0 mg/kg/day) and tested in a Morris maze, with four trials per day for four days. A 15-s probe trial preceded testing on days 2-4. On day 5, the rats were given four trials to learn a new platform location. Scopolamine produced dose-dependent increases in latency to find the platform for all groups. There were no significant differences among prenatal treatment groups in scopolamine-induced shifts in performance. The results did not support the hypothesis that prenatal alcohol-induced CNS cholinergic dysfunction is related to spatial learning performance in these rats.