Evaluation of data imputation strategies in complex, deeply-phenotyped data sets: the case of the EU-AIMS Longitudinal European Autism Project

An increasing number of large-scale multi-modal research initiatives has been conducted in the typically developing population, e.g. Dev. Cogn. Neur. 32:43-54, 2018; PLoS Med. 12(3):e1001779, 2015; Elam and Van Essen, Enc. Comp. Neur., 2013, as well as in psychiatric cohorts, e.g. Trans. Psych. 10(1):100, 2020; Mol. Psych. 19:659–667, 2014; Mol. Aut. 8:24, 2017; Eur. Child and Adol. Psych. 24(3):265–281, 2015. Missing data is a common problem in such datasets due to the difficulty of assessing multiple measures on a large number of participants. The consequences of missing data accumulate when researchers aim to integrate relationships across multiple measures. Here we aim to evaluate different imputation strategies to fill in missing values in clinical data from a large (total N = 764) and deeply phenotyped (i.e. range of clinical and cognitive instruments administered) sample of N = 453 autistic individuals and N = 311 control individuals recruited as part of the EU-AIMS Longitudinal European Autism Project (LEAP) consortium. In particular, we consider a total of 160 clinical measures divided in 15 overlapping subsets of participants. We use two simple but common univariate strategies—mean and median imputation—as well as a Round Robin regression approach involving four independent multivariate regression models including Bayesian Ridge regression, as well as several non-linear models: Decision Trees (Extra Trees., and Nearest Neighbours regression. We evaluate the models using the traditional mean square error towards removed available data, and also consider the Kullback–Leibler divergence between the observed and the imputed distributions. We show that all of the multivariate approaches tested provide a substantial improvement compared to typical univariate approaches. Further, our analyses reveal that across all 15 data-subsets tested, an Extra Trees regression approach provided the best global results. This not only allows the selection of a unique model to impute missing data for the LEAP project and delivers a fixed set of imputed clinical data to be used by researchers working with the LEAP dataset in the future, but provides more general guidelines for data imputation in large scale epidemiological studies.

Comparison of neural substrates of temporal discounting between youth with autism spectrum disorder and with obsessive-compulsive disorder

BACKGROUND

Autism spectrum disorder (ASD) and obsessive-compulsive disorder (OCD) share abnormalities in hot executive functions such as reward-based decision-making, as measured in the temporal discounting task (TD). No studies, however, have directly compared these disorders to investigate common/distinct neural profiles underlying such abnormalities. We wanted to test whether reward-based decision-making is a shared transdiagnostic feature of both disorders with similar neurofunctional substrates or whether it is a shared phenotype with disorder-differential neurofunctional underpinnings.

METHODS

Age and IQ-matched boys with ASD (N = 20), with OCD (N = 20) and 20 healthy controls, performed an individually-adjusted functional magnetic resonance imaging (fMRI) TD task. Brain activation and performance were compared between groups.

RESULTS

Boys with ASD showed greater choice-impulsivity than OCD and control boys. Whole-brain between-group comparison revealed shared reductions in ASD and OCD relative to control boys for delayed-immediate choices in right ventromedial/lateral orbitofrontal cortex extending into medial/inferior prefrontal cortex, and in cerebellum, posterior cingulate and precuneus. For immediate-delayed choices, patients relative to controls showed reduced activation in anterior cingulate/ventromedial prefrontal cortex reaching into left caudate, which, at a trend level, was more decreased in ASD than OCD patients, and in bilateral temporal and inferior parietal regions.

CONCLUSIONS

This first fMRI comparison between youth with ASD and with OCD, using a reward-based decision-making task, shows predominantly shared neurofunctional abnormalities during TD in key ventromedial, orbital- and inferior fronto-striatal, temporo-parietal and cerebellar regions of temporal foresight and reward processing, suggesting trans-diagnostic neurofunctional deficits.

15q11.2 CNV affects cognitive, structural and functional correlates of dyslexia and dyscalculia

Several copy number variants have been associated with neuropsychiatric disorders and these variants have been shown to also influence cognitive abilities in carriers unaffected by psychiatric disorders. Previously, we associated the 15q11.2(BP1-BP2) deletion with specific learning disabilities and a larger corpus callosum. Here we investigate, in a much larger sample, the effect of the 15q11.2(BP1-BP2) deletion on cognitive, structural and functional correlates of dyslexia and dyscalculia. We report that the deletion confers greatest risk of the combined phenotype of dyslexia and dyscalculia. We also show that the deletion associates with a smaller left fusiform gyrus. Moreover, tailored functional magnetic resonance imaging experiments using phonological lexical decision and multiplication verification tasks demonstrate altered activation in the left fusiform and the left angular gyri in carriers. Thus, by using convergent evidence from neuropsychological testing, and structural and functional neuroimaging, we show that the 15q11.2(BP1-BP2) deletion affects cognitive, structural and functional correlates of both dyslexia and dyscalculia.

The effects of acute fluoxetine administration on temporal discounting in youth with ADHD

BACKGROUND

Serotonin is under-researched in attention deficit hyperactivity disorder (ADHD), despite accumulating evidence for its involvement in impulsiveness and the disorder. Serotonin further modulates temporal discounting (TD), which is typically abnormal in ADHD relative to healthy subjects, underpinned by reduced fronto-striato-limbic activation. This study tested whether a single acute dose of the selective serotonin reuptake inhibitor (SSRI) fluoxetine up-regulates and normalizes reduced fronto-striato-limbic neurofunctional activation in ADHD during TD.

METHOD

Twelve boys with ADHD were scanned twice in a placebo-controlled randomized design under either fluoxetine (between 8 and 15 mg, titrated to weight) or placebo while performing an individually adjusted functional magnetic resonance imaging TD task. Twenty healthy controls were scanned once. Brain activation was compared in patients under either drug condition and compared to controls to test for normalization effects.

RESULTS

Repeated-measures whole-brain analysis in patients revealed significant up-regulation with fluoxetine in a large cluster comprising right inferior frontal cortex, insula, premotor cortex and basal ganglia, which further correlated trend-wise with TD performance, which was impaired relative to controls under placebo, but normalized under fluoxetine. Fluoxetine further down-regulated default mode areas of posterior cingulate and precuneus. Comparisons between controls and patients under either drug condition revealed normalization with fluoxetine in right premotor-insular-parietal activation, which was reduced in patients under placebo.

CONCLUSIONS

The findings show that a serotonin agonist up-regulates activation in typical ADHD dysfunctional areas in right inferior frontal cortex, insula and striatum as well as down-regulating default mode network regions in the context of impulsivity and TD.

Latency as a region contrast: Measuring ERP latency differences with Dynamic Time Warping

Methods for measuring onset latency contrasts are evaluated against a new method utilizing the dynamic time warping (DTW) algorithm. This new method allows latency to be measured across a region instead of single point. We use computer simulations to compare the methods' power and Type I error rates under different scenarios. We perform per-participant analysis for different signal-to-noise ratios and two sizes of window (broad vs. narrow). In addition, the methods are tested in combination with single-participant and jackknife average waveforms for different effect sizes, at the group level. DTW performs better than the other methods, being less sensitive to noise as well as to placement and width of the window selected.

Disorder-dissociated effects of fluoxetine on brain function of working memory in attention deficit hyperactivity disorder and autism spectrum disorder

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are often co-morbid and share performance and brain dysfunctions during working memory (WM). Serotonin agonists modulate WM and there is evidence of positive behavioural effects in both disorders. We therefore used functional magnetic resonance imaging (fMRI) to investigate shared and disorder-specific brain dysfunctions of WM in these disorders, and the effects of a single dose of the selective serotonin reuptake inhibitor (SSRI) fluoxetine.

METHOD

Age-matched boys with ADHD (n = 17), ASD (n = 17) and controls (n = 22) were compared using fMRI during an N-back WM task. Patients were scanned twice, under either an acute dose of fluoxetine or placebo in a double-blind, placebo-controlled randomized design. Repeated-measures analyses within patients assessed drug effects on performance and brain function. To test for normalization effects of brain dysfunctions, patients under each drug condition were compared to controls.

RESULTS

Under placebo, relative to controls, both ADHD and ASD boys shared underactivation in the right dorsolateral prefrontal cortex (DLPFC). Fluoxetine significantly normalized the DLPFC underactivation in ASD relative to controls whereas it increased posterior cingulate cortex (PCC) deactivation in ADHD relative to control boys. Within-patient analyses showed inverse effects of fluoxetine on PCC deactivation, which it enhanced in ADHD and decreased in ASD.

CONCLUSIONS

The findings show that fluoxetine modulates brain activation during WM in a disorder-specific manner by normalizing task-positive DLPFC dysfunction in ASD boys and enhancing task-negative default mode network (DMN) deactivation in ADHD.

Protein kinase B (AKT1) genotype mediates sensitivity to cannabis-induced impairments in psychomotor control

BACKGROUND

What determines inter-individual variability to impairments in behavioural control that may underlie road-traffic accidents, and impulsive and violent behaviours occurring under the influence of cannabis, the most widely used illicit drug worldwide?

METHOD

Employing a double-blind, repeated-measures design, we investigated the genetic and neural basis of variable sensitivity to cannabis-induced behavioural dyscontrol in healthy occasional cannabis users. Acute oral challenge with placebo or Δ9-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, was combined with functional magnetic resonance imaging, while participants performed a response inhibition task that involved inhibiting a pre-potent motor response. They were genotyped for rs1130233 single nucleotide polymorphisms (SNPs) of the protein kinase B (AKT1) gene.

RESULTS

Errors of inhibition were significantly (p = 0.008) increased following administration of THC in carriers of the A allele, but not in G allele homozygotes of the AKT1 rs1130233 SNP. The A allele carriers also displayed attenuation of left inferior frontal response with THC evident in the sample as a whole, while there was a modest enhancement of inferior frontal activation in the G homozygotes. There was a direct relationship (r = -0.327, p = 0.045) between the behavioural effect of THC and its physiological effect in the inferior frontal gyrus, where AKT1 genotype modulated the effect of THC.

CONCLUSIONS

These results require independent replication and show that differing vulnerability to acute psychomotor impairments induced by cannabis depends on variation in a gene that influences dopamine function, and is mediated through modulation of the effect of cannabis on the inferior frontal cortex, that is rich in dopaminergic innervation and critical for psychomotor control.

Drug-specific laterality effects on frontal lobe activation of atomoxetine and methylphenidate in attention deficit hyperactivity disorder boys during working memory

BACKGROUND

The catecholamine reuptake inhibitors methylphenidate (MPH) and atomoxetine (ATX) are the most common treatments for attention deficit hyperactivity disorder (ADHD). This study compares the neurofunctional modulation and normalization effects of acute doses of MPH and ATX within medication-naive ADHD boys during working memory (WM).

METHOD

A total of 20 medication-naive ADHD boys underwent functional magnetic resonance imaging during a parametric WM n-back task three times, under a single clinical dose of either MPH, ATX or placebo in a randomized, double-blind, placebo-controlled, cross-over design. To test for normalization effects, brain activations in ADHD under each drug condition were compared with that of 20 age-matched healthy control boys.

RESULTS

Relative to healthy boys, ADHD boys under placebo showed impaired performance only under high WM load together with significant underactivation in the bilateral dorsolateral prefrontal cortex (DLPFC). Both drugs normalized the performance deficits relative to controls. ATX significantly enhanced right DLPFC activation relative to MPH within patients, and significantly normalized its underactivation relative to controls. MPH, by contrast, both relative to placebo and ATX, as well as relative to controls, upregulated the left inferior frontal cortex (IFC), but only during 2-back. Both drugs enhanced fronto-temporo-striatal activation in ADHD relative to control boys and deactivated the default-mode network, which were negatively associated with the reduced DLPFC activation and performance deficits, suggesting compensation effects.

CONCLUSIONS

The study shows both shared and drug-specific effects. ATX upregulated and normalized right DLPFC underactivation, while MPH upregulated left IFC activation, suggesting drug-specific laterality effects on prefrontal regions mediating WM.

Abstract P2-16-09: Retrospective analysis of long-term survivors with HER2+ metastatic breast cancer (MBC) treated with trastuzumab in a community setting

Background: The median survival for patients (pts) receiving trastuzumab (T) in the metastatic setting is approximately 3 years. There are limited data on real world use and outcomes in T treated pts who live longer than 3 years. The objective of this study was to identify and characterize pts with HER2+ MBC who initiated treatment with T (alone or in combination) in a community setting and to determine their treatment patterns and outcomes, including duration of treatment, overall survival (OS) and time to permanent discontinuation of T. Methods: A retrospective observational study was performed using the IKnowMed electronic medical record (EMR) used by the US Oncology Network with the primary time period of 2007 through Dec. 2012. Eligible pts had at least 2 visits at practice locations with full EMR capability. Pts on T when the EMR was implemented had chart review to determine the dates of diagnosis and start of T treatment. Results: The study population included 1856 women with HER2+ MBC who started T (alone or in combination with chemotherapy or hormonal therapy); 873 presented with MBC and 983 developed recurrence following diagnosis of early-stage disease. The median age was 58, range 23 to 96, 59% had ER+ cancer, 64% were postmenopausal and 35% had multiple sites of disease at presentation. Median OS for the entire group was 40.9 months and the median time to permanent discontinuation of T was slightly less, at 39.9 months. Interestingly, the median OS and duration of T use were similar in the recurrent MBC population and in the population who presented with de novo MBC. The proportion of pts receiving T and OS by year are presented (Table). Thirty-two percent of pts are still alive at 6 years, with 17% continuing to receive T.

Outcomes of 1856 Patients Treated with TrastuzumabYear1356Pts still receiving T (%)82%53%27%17%OS (%)84%54%36%32%

Ongoing analysis will evaluate whether there are pt and treatment characteristics that may predict for longer term OS. Conclusions: Using an EMR database we identified 1856 women with HER2+ MBC who initiated treatment with T (alone or in combination) with one third still alive at 5 years and 27% still on T. Future research that focuses on understanding the characteristics of this population can potentially improve care for women with HER2+ MBC with T and newer anti-HER2 agents.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-09.

Pattern recognition analysis of anterior cingulate cortex blood flow to classify depression polarity

Differentiating bipolar from recurrent unipolar depression is a major clinical challenge. In 18 healthy females and 36 females in a depressive episode--18 with bipolar disorder type I, 18 with recurrent unipolar depression--we applied pattern recognition analysis using subdivisions of anterior cingulate cortex (ACC) blood flow at rest, measured with arterial spin labelling. Subgenual ACC blood flow classified unipolar v. bipolar depression with 81% accuracy (83% sensitivity, 78% specificity).

Pooled analysis of cardiac safety in patients with cancer treated with pertuzumab

BACKGROUND

Pertuzumab, a human epidermal growth factor receptor (HER) 2 dimerization inhibitor, has demonstrated promising efficacy in combination with trastuzumab in patients with metastatic breast cancer. As HER signaling pathways are not only involved in oncogenesis, but also in myocardial homeostasis, an analysis of cardiac safety data was undertaken in a large group of patients treated with pertuzumab.

PATIENTS AND METHODS

A complete database of patients treated with full-dose pertuzumab was used to describe the incidence of asymptomatic left ventricular systolic dysfunction (LVSD) and symptomatic heart failure (HF).

RESULTS

Information for 598 unique patients was available for the current analysis. Of the patients treated with pertuzumab alone (n = 331) or pertuzumab in combination with a non-anthracycline-containing cytotoxic (n = 175) or trastuzumab (n = 93), 23 (6.9%), 6 (3.4%), and 6 (6.5%), respectively, developed asymptomatic LVSD and 1 (0.3%), 2 (1.1%), and 1 (1.1%), respectively, displayed symptomatic HF. None of the 15 patients receiving both pertuzumab and erlotinib demonstrated LVSD.

CONCLUSIONS

Patients treated with pertuzumab experienced relatively low levels of asymptomatic LVSD or symptomatic HF. There was no notable increase in cardiac side-effects when pertuzumab was given in combination with other anticancer agents.

P5-20-01: Patient Valuation of Reduced Risk of Side Effects during Treatment for Metastatic Breast Cancer

Background

Chemotherapy treatment for metastatic breast cancer (MBC) has shown significant benefits in survival for breast cancer patients. However, chemotherapy is associated with several side effects that have a significant impact on patients’ quality of life. The objective of this analysis was to quantify the value patients with MBC place on reduced risk of treatment side effects.

Methods: A willingness to pay (WTP) survey was developed to assess metastatic breast cancer patients’ willingness to pay for a reduction in the risk of breast cancer treatment side effects. The survey assessed patients’ WTP for a 25%, 50% and 100% reduction in the risk of all side effects. Patients were also asked to select the side effect they would pay the most to avoid. Additionally, the survey collected demographic information such as treatment regimen, age, race/ethnicity, region, employment status, and insurance type.

Results: The survey was completed by 202 metastatic breast cancer patients. Most survey respondents were white (94%), married (62%), and over the age of 51 (78%). Most patients were covered by private insurance (67%) or Medicare (24%). Of the 58% of respondents who remembered paying out of pocket for their last treatment, the average out of pocket payment was $459. Survey respondents were willing to pay an extra $1,886, $3,837 and $7,794 for a 25%, 50% and 100% reduction in the risk of all side effects, respectively. Hair loss (28%), pain (17%) and nausea (15%) were selected most often as the side effect respondents would pay the most to avoid.

Discussion: Chemotherapy for MBC is associated with several adverse events that patients would like to avoid or reduce such as hair loss, pain, nausea and neutropenia. This analysis demonstrates patients with MBC place a significant value on reducing the risk of side effects and are willing to pay 4.2 times for a treatment devoid of side effects as compared to a treatment with a 25% reduction in the risk of treatment side effects.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-20-01.

Altered patterns of cortical activation in ALS patients during attention and cognitive response inhibition tasks

Since amyotrophic lateral sclerosis (ALS) can be accompanied by executive dysfunction, it is hypothesised that ALS patients will have impaired performance on tests of cognitive inhibition. We predicted that ALS patients would show patterns of abnormal activation in extramotor regions when performing tests requiring the inhibition of prepotent responses (the Stroop effect) and the inhibition of prior negatively primed responses (the negative priming effect) when compared to healthy controls. Functional magnetic resonance imaging was used to measure activation during a sparse sequence block design paradigm investigating the Stroop and negative priming effects in 14 ALS patients and 8 healthy age- and IQ-matched controls. Behavioural measures of performance were collected. Both groups' reaction times (RTs) reflected the Stroop effect during scanning. The ALS and control groups did not differ significantly for any of the behavioural measures but did show significant differences in cerebral activation during both tasks. The ALS group showed increased activation predominantly in the left middle temporal gyrus (BA 20/21), left superior temporal gyrus (BA 22) and left anterior cingulate gyrus (BA 32). Neither group's RT data showed clear evidence of a negative priming effect. However the ALS group showed decreased activation, relative to controls, particularly in the left cingulate gyrus (BA 23/24), left precentral gyrus (BA 4/6) and left medial frontal gyrus (BA 6). Greater cerebral activation in the ALS group accompanying the performance of the Stroop effect and areas of decreased activation during the negative priming comparison suggest altered inhibitory processing in ALS, consistent with other evidence of executive dysfunction in ALS. The current findings require further exploration in a larger study.

Abstract P5-12-04: Symptom Burden Declines When Breast Cancer Patients Treated with Adjuvant Trastuzumab/Combination Chemotherapy Regimens Enter Trastuzumab Monotherapy Follow-Up

Background: Trastuzumab (T) is indicated for the adjuvant treatment of HER2-overexpressing breast cancer (BC). We report the results of a retrospective study of patient-reported outcomes (PROs) for patients who received T plus chemotherapy followed by T monotherapy or T as a single-agent.

Methods: Included in this analysis were 210 patients with early HER2+ BC treated in community oncology practices affiliated with ACORN Research, who completed a 38-item symptom assessment scale, the Patient Care Monitor (PCM). Treatment regimens were classified as: combination chemotherapy followed by T monotherapy: doxorubicin, cyclophosphamide, paclitaxel [n=74] or docetaxel [n=18] and T (AC→TH/ACTH) (n=92); docetaxel, carboplatin, and T (TCH) (n = 38); or “Other” chemotherapy/T (n=47); or T only (n=33). Medical records were abstracted and symptom burden was measured by PCM index scores for: Physical Symptoms, Treatment Side Effects, Distress, Despair, Impaired Ambulation, and Impaired Performance. Linear mixed models were used to examine change in PCM index scores over time, controlling for first line chemotherapy group and relevant covariates. Results: Patients were 66% Caucasian and 28% African American. The mean age of, this cohort was 56.0 years (range=31-85 years). Demographic and disease characteristic s did not differ among the four treatment regimens except patients treated with AC→TH/ACTH tended to have higher stage of disease at time of diagnosis. Among patients on combination chemotherapy, median time on active chemotherapy was 3.5 months. Patients were observed for a median of 12.5 months. Impaired Ambulation, Impaired Performance, and General Physical Symptoms worsened over the course of active chemotherapy (p < .05), whereas Treatment Side Effects were worse from the start and remained stable during active chemotherapy. When chemotherapy stopped and patients entered T monotherapy, General Physical Symptoms and Treatment Side Effects improved significantly, but showed less improvement for TCH than for the other 2 groups (p < .05). Symptom burden improved during T monotherapy for TCH, AC→TH/ACTH and “Other”, generally converging with scores for patients who had T only, which tended to be lower and more stable. With the exception of younger patients showing more Distress, patient level characteristics (age, race, BMI, stage) were not significantly predictive of symptom burden trajectory and change.

Discussion: Functioning and physical symptom burden tended to worsen during active chemotherapy and to improve when active chemotherapy stopped. TCH was associated with more gradual improvement in symptom burden than AC→TH/ACTH and the “Other” combination group. Most patients treated with combination chemotherapy showed symptom burden similar to those treated with T only once they transitioned to T monotherapy as follow-up treatment.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-12-04.

Abstract P6-14-16: A Systematic Review of the Evidence for Treatment of Metastatic Breast Cancer beyond 2nd Line

Background: Optimal treatment of metastatic breast cancer (MBC) post second-line is not well defined. Therapy options are limited by previous exposure, while HER2 status may remain relevant to decision-making. A systematic review was conducted to identify trials reporting efficacy data, and review the current treatment landscape for HER2+ and - patients for third and later line treatment of MBC.

Methods: A systematic search strategy from Medline, EMBASE and Cochrane (CCTR) databases retrieved citations for two-stage review. Citations that reported 3rd or later line treatment of MBC patients were included. Selected conference proceedings from the last 3-5 years were searched for relevant abstracts and posters. Included studies were restricted to those with data reported for 10 or more patients.

Results: 39 citations from 29 trials, investigating 22 treatment regimens, were identified which reported efficacy data specific for a 3rd or later line population: in 22 trials, this was a sub-group analysis of a mixed line population. 76% of included studies were single arm: only 1 RCT was identified. 21% of included studies investigated the treatment of HER2+ populations; no studies reported outcomes specific for the HER2- population. Overall response rate (ORR) was the most reported outcome. The majority of responses were partial, complete response was rarely observed beyond 2nd line. Overall and progression-free survival were rarely reported. The highest ORR was reported for mitomycin C and capecitabine in HER2 mixed patients. Table 1 presents response rates reported in HER2+ patients.

Conclusions: There does not appear to be a standard regimen used in the treatment of patients beyond the second line. In patients with HER2+ breast cancer, T-DM1 had the highest reported response rate.

The interactive effect of acute ovarian suppression and the cholinergic system on visuospatial working memory in young women

Women have an increased risk of developing Alzheimer's Dementia (AD) compared to men. It has been postulated that this risk may be modulated by a reduction in the neuroprotective effects of estrogen on the brain in the early postmenopausal period. This view is supported by, for example, findings that ovariectomy in younger women (i.e. prior to menopause) significantly increases the risk for the development of memory problems and AD in later life. However, the biological basis underlying these cognitive changes is still poorly understood. Our aim in the current study was to understand the interactive effects of acute, pharmacological-induced menopause (after Gonadotropin Hormone Releasing Hormone agonist (GnRHa) treatment) and scopolamine (a cholinergic antagonist used to model the memory decline associated with aging and AD) on brain functioning. To this end we used fMRI to study encoding during a Delayed Match to Sample (DMTS) (visual working memory) task. We report a relative attenuation in BOLD response brought about by scopolamine in regions that included bilateral prefrontal cortex and the left parahippocampal gyrus. Further, this was greater in women post-GnRHa than in women whose ovaries were functional. Our results also indicate that following pharmacological-induced menopause, cholinergic depletion produces a more significant behavioural deficit in overall memory performance, as manifest by increased response time. These findings suggest that acute loss of ovarian hormones exacerbate the effects of cholinergic depletion on a memory-related, behavioural measure, which is dependent on fronto-temporal brain regions. Overall, our findings point to a neural network by which acute loss of ovarian function may interact to negatively impact encoding.

The functional neuroanatomy of blood-injection-injury phobia: a comparison with spider phobics and healthy controls

BACKGROUND

Most neuroimaging studies of specific phobia have investigated the animal subtype. The blood-injection-injury (BII) subtype is characterized by a unique biphasic psychophysiological response, which could suggest a distinct neural substrate, but direct comparisons between phobia types are lacking.

METHOD

This study compared the neural responses during the presentation of phobia-specific stimuli in 12 BII phobics, 14 spider (SP) phobics and 14 healthy controls using functional magnetic resonance imaging (fMRI).

RESULTS

Subjective ratings showed that the experimental paradigm produced the desired symptom-specific effects. As in many previous studies, when viewing spider-related stimuli, SP phobics showed increased activation in dorsal anterior cingulate and anterior insula, compared to BII phobics and healthy controls. However, when viewing images of blood-injection-injuries, participants with BII phobia mainly showed increased activation in the thalamus and visual/attention areas (occipito-temporo-parietal cortex), compared with the other two groups. The degree of provoked anxiety and disgust by phobia-relevant images was strongly associated with activation in several common regions across the two phobia groups (thalamus, cerebellum, occipito-temporal regions) but only correlated with activation in the dorsal anterior cingulate gyrus and the anterior insula in the SP phobics.

CONCLUSIONS

These results suggest partially distinct neurobiological substrates of animal and BII phobias and support their current classification as two distinct subtypes in the DSM-IV-TR. Further research is needed to better understand the precise neurobiological mechanisms in BII phobia and particularly the fainting response.

Pooled Analysis of Cardiac Safety in Patients Treated with Pertuzumab

Background: Pertuzumab, a monoclonal antibody, is a human epidermal growth factor receptor 2 (HER2)-dimerisation inhibitor directed to the dimerisation epitope of HER2, with promising activity when given with trastuzumab to patients with HER2-positive metastatic breast cancer following progression on trastuzumab.1 As anti-HER2 treatment has been associated with cardiac dysfunction, we investigated the incidence of reduced left ventricular ejection fraction (LVEF) and congestive heart failure (CHF) in patients treated with pertuzumab as single agent or in combination with cytotoxic or anti-HER therapy.Methods: We analysed patients in completed Phase II studies with pertuzumab. Cardiac dysfunction was defined as: 1) reduced LVEF (baseline normal: LVEF reduced ≥10% absolute and to below 50%); 2) symptomatic CHF: any symptoms suggestive of CHF counted (severity then classified according to New York Heart Association).Results: In 554 patients analysed, the overall incidence of reduced LVEF was 5.8% and of CHF 0.7%. Individual data for patients in different treatment protocols are shown in Table 1. PatientsReduced LVEFCHF (n)(n/%)(n/%)Pertuzumab as single agent (24% with prior anthracyclines)30221/7.01/0.3Pertuzumab with cytotoxic therapy1756/3.42/1.1Pertuzumab with trastuzumab (71% with prior anthracyclines)775/6.51/1.3 The majority of patients with reduced LVEF or symptomatic CHF had significant improvement or return to baseline function on follow-up or with standard cardiac medication.Conclusions: Overall, the incidence of cardiac dysfunction in Phase II studies of patients treated with pertuzumab was low. When combined with trastuzumab in selected patients, there is no apparent indication that pertuzumab exacerbates the known risk of reduced LVEF and CHF with trastuzumab.2 These data suggest that the combination of pertuzumab with trastuzumab or chemotherapy for HER2-positive breast cancer appears safe from a cardiac perspective with appropriate monitoring in ongoing studies.References1. Gelmon K et al. Poster 1026 presented at the 44th ASCO Annual Meeting, Chicago, Illinois, USA, 30 May-3 June, 20082. Muehlbauer S et al. Abstract presented at SABCS 2008; abs 6136

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5088.

Neural markers of symptomatic improvement during antidepressant therapy in severe depression: subgenual cingulate and visual cortical responses to sad, but not happy, facial stimuli are correlated with changes in symptom score

Resting state activity in the ventral cingulate may be an important neural marker of symptomatic improvement in depression. The number of task related functional magnetic resonance imaging (fMRI) studies correlating blood oxygenation level dependent (BOLD) response with symptomatic improvement is limited and methodologies are still evolving. We measured BOLD responses to sad and happy facial stimuli in 12 severely depressed individuals in the early stages of antidepressant treatment (Time 1) and 12 weeks later (Time 2) using event-related fMRI. We calculated correlations between temporal changes in BOLD response and changes in symptom scores. Most subjects improved markedly by Time 2. At Time 1, depression severity correlated positively with responses to sad stimuli in the right visual cortex, subgenual cingulate, anterior temporal pole and hippocampus and correlated negatively with responses to happy stimuli in left visual cortex and right caudate. Decreases in individual effect sizes of right subgenual cingulate and right visual cortical responses to sad, but not happy, facial stimuli were correlated with decreases in symptom scores. There are contrasting cortical and subcortical responses to sad and happy stimuli in severe depression. Responses to sad stimuli show the strongest correlates of clinical improvement, particularly in the subgenual cingulate.

Age-related neural activity during allocentric spatial memory

Age-related decline in allocentric (viewer-independent) spatial memory is seen across species. We employed a virtual reality analogue of the Morris Water Maze to study the effect of healthy ageing on neural activity during allocentric spatial memory using functional magnetic resonance imaging. Voxel-based morphometry was used to ascertain hippocampal volumetric integrity. A widespread neural network comprising frontal, parietal, occipital, thalamic, and cerebellar regions was activated in young and older adults, but only young adults significantly activated bilateral hippocampus and left parahippocampus, as well as right frontal pole and dorso-lateral prefrontal cortex (DLPFC) during encoding and right DLPC during retrieval. Hippocampal grey matter volume was unchanged in older adults; however, prefrontal and parahippocampal functional attenuation was accompanied by volumetric reduction. We conclude that the decline in allocentric spatial memory with age is associated with attenuated hippocampal function, as well as compromised function and structure of prefrontal and parahippocampal regions.

registHER: Treatment outcomes in patients with HER2-positive (HER2+), hormone receptor-positive (HR+) metastatic breast cancer (MBC)

1057

Background: Approximately 50% of HER2+ breast cancers are HR+ (defined as estrogen receptor [ER] and/or progesterone receptor [PR] positive). Cross talk between growth factor and ER-dependent signaling pathways may affect growth regulation in HER2+ breast cancers. Blockade of both pathways appears to be more active than blocking either alone based on randomized trials performed in selected populations. However, the outcomes of HER2+ and HR+ MBC patients relative to those in real- life clinical practice have not been evaluated in large cohort studies. Methods: registHER is a prospective observational study of 1023 patients with newly diagnosed (within 6 months [mo]) HER2+ MBC treated in community/academic settings, enrolled from 12/03 to 2/06. Median follow-up from MBC diagnosis was 25 mo at data cutoff (1/02/08). Treatment patterns and outcomes in patients with HER2+/HR+ MBC receiving 1st-line therapy (i.e., therapies received prior to 1st progression) are described in this analysis. Results: Of the 963 (94%) treated HER2+ patients with recorded HR tumor status, 55% (533) were HR+ and 45% (430) were HR-negative. 1st-line MBC treatment regimens for HER2+/HR+ patients included endocrine therapy (E) only, 57 (10.7%); E + trastuzumab (T), 50 (9.4%); chemotherapy (C) ± E, 41 (7.7%); and C + trastuzumab (T) ± E, 361 (67.7%). Progression-free survival (PFS) and overall survival (OS) by 1st line treatment groups are in the table. Conclusions: In registHER, HER2+/HR+ patients treated with E+T had longer PFS than patients treated with E alone; E- alone median PFS is consistent with findings in prospective randomized trials. These data provide further information regarding trastuzumab's role in targeting dual pathways in HER2+/HR+ MBC patients in a real-world setting. Multivariate analysis to address potential bias from known prognostic factors that may influence treatment choice will be presented.

[Table: see text]

[Table: see text]

A retrospective study evaluating treatment patterns and outcomes in patients receiving trastuzumab for treatment of first-line and second-line metastatic breast cancer (mBC)

e12008

Background: Practice patterns for patients with MBC following 1st line therapy have often continued trastuzumab treatments while changing other chemotherapeutic agents in the regimen. We described treatment patterns, switching patterns and progression in mBC patients treated with a trastuzumab containing regimen for 1st and second line mBC. Methods: A retrospective, longitudinal, observational study of patients with mBC during 1/1/2003 up to 6/30/2008. The dataset comprised 304,654 cancer patients from 91practice sites across 23 states using Varian or Impac electronic medical records (EMRs). The start and end of a line of therapy was defined by a regimen change or a > 42 day gap in the regimen. In addition to the database analyses, a manual chart review was also conducted for 20% of the study sample to validate the source data and results. Patients were required to be observed for ≥ 9 months from index. Mean, median, standard deviation, and standard error for the duration in days by line and regimen was calculated as well as an overall weighted mean by line. Results: The study sample of 239 patients post-mBC was treated with the following regimens in the Table. Conclusion: Trastuzumab is most frequently given with taxanes in the first and second line settings. In the second line trastuzumab monotherapy, vinorelbine and gemcitabine were also frequently used. First line therapy may influence the selection of second line therapy. As EMRs often reflect care primarily at the practice site, prescribing of oral agents should be further researched.

[Table: see text]

[Table: see text]

Trastuzumab use and CNS metastasis in Medicare patients diagnosed with metastatic breast cancer (MBC)

1123

Background: While trastuzumab was approved in 1998 for treating patients with HER-2-positive MBC, there is little information on its use in the Medicare setting. Methods: We used SEER-Medicare data to examine patterns of trastuzumab use in women diagnosed with MBC . An index date was defined as either the date of diagnosis (stage IV) or of first distant recurrence (stage 0-III). Included patients were diagnosed in 2000–2002, and had their first claim for trastuzumab between their index date and December 31, 2005, the end of the observation period. Patients were divided into those who received trastuzumab as part of their first treatment following their index date (Group A), and those who began trastuzumab after at least one course of chemotherapy (Group B). Chemotherapy agents were grouped into antimicrotubule (vinorelbine, docetaxel, paclitaxel, vincristine), anthracycline (doxorubicin, epirubicin), cyclophosphamide, other, and unknown. Results: 281 patients met the inclusion criteria. Overall, the median (mean) time from the index date to initial chemotherapy and/or trastuzumab treatment was 35 (94) days (range 1–1,587 days). The average duration of trastuzumab use (first to last administration) was 371 days (median 239), during which patients averaged 2.3 trastuzumab claims per month. There were 192 (68%) patients in Group A. The median (mean) time from diagnosis to initial treatment in Group A was 34 (94) days. 64 (33%) received trastuzumab alone, and 121 (63%) received trastuzumab with an antimicrotubule. In Group B (89 patients), the median (mean) time to initial chemotherapy was 41 (92) days. 36 (40%) received anthracycline and/or cyclophosphamide based therapy, 22 (25%) received an antimicrotubule without either an anthracycline or cyclophosphamide. The median (mean) time from initial chemotherapy to initial trastuzumab therapy was 233 (368) days. At that time, 29 (33%) received trastuzumab alone, and 54 (61%) received trastuzumab plus an antimicrotubule. Conclusions: To our knowledge, this is the first study to describe patterns of trastuzumab use in Medicare. When used for metastatic breast cancer, trastuzumab was most often provided soon after diagnosis as part of initial treatment, and usually with an antimicrotubule agent.

[Table: see text]

First-line trastuzumab utilization: Patterns of care and progression in the community setting

e12009

Background: This study describes patterns of care and outcomes in metastatic breast cancer (MBC) patients treated with trastuzumab (T) within the US Oncology network. Methods: This retrospective study utilized data from US Oncology's iKnowMed EMR system. HER-2 (+) MBC patients who initiated a first-line regimen containing T between January 1, 2006 and July 31, 2007, were identified. Patients were divided into three treatment cohorts: A) those who discontinued T prior to disease progression; B) those who continued T following discontinuation of chemotherapy prior to progression; and C) those who received T monotherapy. Patients were followed through October 31, 2008, to measure treatment duration and observe progression (as defined as escalation to second-line therapy). The Kaplan Meier method/log-rank test were used to estimate and compare progression free survival (PFS) across cohorts. Results: We identified 139 patients receiving first-line therapy including T. The median age was 58 years and 84 patients were ER and/or PR (+). The top 5 chemotherapy regimens included T plus: paclitaxel (n = 14); docetaxel (n = 14); vinorelbine (n = 14); carboplatin/paclitaxel (n = 12); carboplatin/docetaxel (n = 7 pts). Twenty-one (15%) patients were in cohort A, 55 (40%) were in cohort B, and 63 (45%) were in cohort C. Overall, the median duration of first-line T use was 281 days (mean = 287; range = 1–862). Following the initiation of first-line therapy, a total of 56 (40%) patients progressed (median follow up = 15 months). Following progression, 22 (39%) patients received second-line regimens containing T. The overall median PFS was 17.4 months (mean = 18.6). Patients in cohort A (n = 15) had significantly shorter PFS versus patients in cohort B/C (median 3.9 and 19.6 months, respectively; p < 0.001). Conclusions: In this observational study within the outpatient community setting, persistent first-line T use for MBC was associated with delayed disease progression. Future research should evaluate the causal relationship of this association. In addition, a more comprehensive evaluation should be conducted of therapies prescribed concomitant to T for patients treated with T “monotherapy.”

[Table: see text]

Audiovisual integration of speech in a bistable illusion

Visible speech enhances the intelligibility of auditory speech when listening conditions are poor [1], and can modify the perception of otherwise perfectly audible utterances [2]. This audiovisual perception is our most natural form of communication and one of our most common multisensory phenomena. However, where and in what form the visual and auditory representations interact is still not completely understood. Although there are longstanding proposals that multisensory integration occurs relatively late in the speech-processing sequence [3], considerable neurophysiological evidence suggests that audiovisual interactions can occur in the brain stem and primary sensory cortices [4, 5]. A difficulty testing such hypotheses is that when the degree of integration is manipulated experimentally, the visual and/or auditory stimulus conditions are drastically modified [6, 7]; thus, the perceptual processing within a modality and the corresponding processing loads are affected [8]. Here, we used a bistable speech stimulus to examine the conditions under which there is a visual influence on auditory perception in speech. The results indicate that visual influences on auditory speech processing, at least for the McGurk illusion, necessitate the conscious perception of the visual speech gestures, thus supporting the hypothesis that multisensory speech integration is not completed in early processing stages.

Total societal costs attributable to the prevention of recurrent HER2+ breast cancer

Abstract #6101

Introduction: Adjuvant therapies are available to prevent breast cancer recurrence that may reduce morbidity and mortality. However, the associated savings to society have not been quantified, particularly for HER2+ patients. Methods: We reviewed the literature (PubMed) to estimate the costs attributable to breast cancer recurrence including direct (medical and non-medical) and indirect (loss income, productivity, informal care) costs. The following sources were used to estimate the recurrence cost. The 10-year average direct medical costs of recurrence were obtained from an analysis of SEER-Medicare data (Stokes 2008). This study compared women with recurrence to similar women without recurrence and accounts for differential costs associated with survival (ie, it did not estimate only the cost of treating recurrent cancer). In the initial year after cancer diagnosis, women required an additional 66 hours of personal time to obtain medical services (Yabroff 2007). After recurrence, an excess of 9% of patients would leave the work force if they were aged 50-64 (Lidgren 2007). Women were found to take an additional 8.5 months away from work during the 3 years following a recurrence compared with those without recurrence (Drolet 2005). The intensity of informal care was similar (0.8 hour/week) in the first year after recurrence as it was for women without recurrence (Lidgren 2007). The valuation of utilization was conducted from a societal perspective and costs reported as 2008 US dollars. Because certain costs were relevant to specific ages, we estimated costs in 3 age cohorts (30-49, 50-69, and ≥70). Lost income from early retirement was calculated as the number of years retired from work before the age 65 times the annual average income derived using the national average wage and benefit data. Patient time required for receiving care, time absent from work, and caregiver time were also valued in the same way. We combined this information into a simulation used to estimate the number of HER2+ women diagnosed in one calendar year in the United States, and whose recurrence could be prevented with trastuzumab. The model accounted for variability of clinical and economic inputs by sampling from distributions using 5,000 replications. The mean costs per person and the middle 95% of the distribution were reported. Results: For ages 50-69, early retirement costs were $39,600. Costs due to work absences were $41,600 (age 30-49) and were $31,200 (age 50-69). The total societal costs attributable to a single recurrence were $60,400 ($32,000 to $129,000) for ages 30-49, $89,600 ($45,000 to $203,000) for ages 50-69, and $18,900 ($13,000 to $25,000) for ages ≥70. Overall, the savings from preventing recurrence with trastuzumab were estimated at over $167 million ($70 million to $385 million) per year of diagnosed cases of HER2+ tumors. Conclusion: Therapies that can prevent breast cancer recurrence can lead to substantial savings to society and represent a considerable opportunity cost.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6101.

Estimating recurrences prevented from using trastuzumab in adjuvant breast cancer in the United States

Abstract #2107

Introduction: Trastuzumab was recently approved for adjuvant use in HER2+ breast cancer. Adjuvant treatment should result in a reduction in recurrences, but this has not been estimated from a US population perspective. Methods: We estimated the number of HER2+ breast cancers in the US in 2005 using SEER data. Because HER2 status is not available in SEER, the number of HER2+ patients was estimated using the known relationship between HER2 status and both estrogen receptor (ER) and progesterone receptor (PR) status. Patients with no ER or PR results were assumed to have no HER2 testing. HER2+ proportions for remaining ER+/PR+, ER+/PR-, ER-/PR+ and ER-/PR- patients were estimated from published data and applied to patients diagnosed in the 17 SEER registries. The resulting rates were applied to the 2005 US female population counts. Estimated HER2+ patient counts were stratified by nodal status (+/-), and age (30-50, 50-70, and &gt;70 years). Patients with significant underlying cardiovascular (CV) disease were assumed not to use trastuzumab. Underlying recurrence rates were pooled across studies that compared doxorubicin and cyclophosphamide followed by a taxane (AC-T) versus the same regimen plus 52 weeks of trastuzumab (AC-TH). Rates were stratified by nodal status. The relative risk of recurrence with trastuzumab (0.53) was assumed to be constant across subgroups based on published data, and assumed to persist for 5 years. One study (NSABP B-31) estimated the proportion experiencing a CV event (primarily defined as ejection fraction decline below threshold or dyspnea with normal activity) based on 5-year follow-up. Probabilistic model inputs were used to reflect the likelihood of possible values where possible. The results were run using 5,000 replications and reported as the mean and middle 95% of the distribution using @Risk (Palisade Corp., Ithaca, NY). Results: The model estimated that there are approximately 28,500 (95% interval 26,400 to 31,500) patients who could be diagnosed with HER2+ breast cancer in one year in the US, 6,128 (95% interval 4,292 to 8,600) of whom will have a recurrence within 5 years, and up to 2,619 of whom (95% interval 1,506 to 3,701) who could be prevented from disease recurrence with trastuzumab use. The number of patients who might experience a CV event is approximately 941 (95% interval 510 to 1,395) giving a ratio of 2.7 recurrences prevented for every CV event (95% interval 1.4 to 5.6). Conclusion: Trastuzumab is capable of preventing at least 2,600 recurrences within 5 years after its initial year of use. Its most clinically important side effect, a CV event, is likely to appear once for every 2.7 recurrences that are prevented, although many cases are asymptomatic and reversible. Extrapolated over 20 years, targeting HER2+ tumors in the adjuvant setting could prevent as many as 50,000 HER2+ patients from recurrence with important clinical, humanistic and economic consequences for patients, physicians and payors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2107.

Survival of patients with HER2+ metastatic breast cancer and use of trastuzumab following progression: analysis of RegistHER

Abstract #3142

Background: Most HER2+ metastatic breast cancer (MBC) patients who initially respond to trastuzumab (T)-based therapies will experience disease progression (PD). Standard practice is to discontinue the cytotoxic agent on which disease progressed, however there is evidence that tumors may remain sensitive to HER2 targeting and that there may be a potentiating effect of T on chemotherapy. We examined the treatment history of a large population of HER2+ MBC patients to assess outcomes associated with continuation of T beyond PD.&#x2028; Methods: This analysis was carried out on patients enrolled in registHER, a prospective observational study of 1023 patients with newly diagnosed (within 6 months) HER2+ MBC. Median f/u from MBC diagnosis is 25 months at the time of data cut-off (12/31/07). For those treated with T prior to first PD, we compared demographics and baseline tumor characteristics for those patients treated with or without T following first PD. Treatment with T was defined as a minimum of 21 days of therapy prior to PD. In addition, we evaluated time to second PD, and overall survival post PD (both endpoints calculated from initial PD). Overall survival (OS) was also calculated from the date of treatment initiation to death for the entire treated cohort.&#x2028; Results: Of 1023 evaluable patients, 873 (85%) were treated with any T-based first-line therapy. 622 T-treated patients progressed and 500 were subsequently treated with T following first PD. Patients who received T post first PD tended to be younger (&lt;50 years of age, 45.2% vs 29.5%) and have hormone receptor positive disease (51.4% vs 42.0%) compared with patients who did not receive T post first PD. Among all treated patients the median overall survival was 35.6 mo (25th-75th-ile:18.6-63.1 mo). Median survival post PD in the 500 patients treated with trastuzumab following first PD was 21.2 mo (25th-75th-ile:11.8-35.8mo).&#x2028; Conclusions: OS in patients on the prospective observational study registHER is longer than the OS of 25.1 months noted in the pivotal trial of first-line HER2+ MBC patients treated with T plus chemotherapy. We will present data on the association between various pre- and post-treatment factors, including the use of T beyond PD, and PFS and OS. This will include a multivariate analysis that specifically examines the association between T use in later lines and survival.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3142.

The interactive effect of the cholinergic system and acute ovarian suppression on the brain: an fMRI study

Recent evidence suggests that loss of ovarian function following ovariectomy is a risk factor for Alzheimer's disease (AD); however, the biological basis of this risk remains poorly understood. We carried out an fMRI study into the interaction between loss of ovarian function (after Gonadotropin Hormone Releasing Hormone agonist (GnRHa) treatment) and scopolamine (a cholinergic antagonist used to model the memory decline associated with aging and AD). Behaviorally, cholinergic depletion produced a deficit in verbal recognition performance in both GnRHa-treated women and wait list controls, but only GnRHa-treated women made more false positive errors with cholinergic depletion. Similarly, cholinergic depletion produced a decrease in activation in the left inferior frontal gyrus (LIFG; Brodmann area 45)--a brain region implicated in retrieving word meaning--in both groups, and activation in this area was further reduced following GnRHa treatment. These findings suggest biological mechanisms through which ovarian hormone suppression may interact with the cholinergic system and the LIFG. Furthermore, this interaction may provide a useful model to help explain reports of increased risk for cognitive decline and AD in women following ovariectomy.

The neural correlates of fatigue: an exploratory imaginal fatigue provocation study in chronic fatigue syndrome

BACKGROUND

Fatigue is the central symptom in chronic fatigue syndrome (CFS) and yet very little is known about its neural correlates. The aim of this study was to explore the functional brain response, using functional magnetic resonance imaging (fMRI), to the imaginal experience of fatigue in CFS patients and controls.

METHOD

We compared the blood oxygen level dependent (BOLD) responses of 12 CFS patients and 11 healthy controls to a novel fatigue provocation procedure designed to mimic real-life situations. A non-fatiguing anxiety-provoking condition was also included to control for the non-specific effects of negative affect.

RESULTS

During the provocation of fatigue, CFS patients reported feelings of both fatigue and anxiety and, compared to controls, they showed increased activation in the occipito-parietal cortex, posterior cingulate gyrus and parahippocampal gyrus, and decreased activation in dorsolateral and dorsomedial prefrontal cortices. The reverse pattern of findings was observed during the anxiety-provoking scenarios.

CONCLUSIONS

The results may suggest that, in CFS patients, the provocation of fatigue is associated with exaggerated emotional responses that patients may have difficulty suppressing. These findings are discussed in relation to the cognitive-behavioural model of CFS.

Caffeine restores regional brain activation in acute hypoglycaemia in healthy volunteers

AIMS

Caffeine enhances counterregulatory responses to acute hypoglycaemia. Our aim was to explore its effects on cortical function, which are not known at present.

METHODS

Regional brain activation during performance of the four-choice reaction time (4CRT) at different levels of complexity was measured using functional magnetic resonance imaging (fMRI) at euglycaemia (5 mmol/l) and hypoglycaemia (2.6 mmol/l) in the presence and absence of caffeine in six healthy right-handed men.

RESULTS

During hypoglycaemia, caffeine enhanced adrenaline responses to hypoglycaemia (2.5 +/- 0.7 nmol/l to 4.0 +/- 1.0 nmol/l, P = 0.01) and restored the brain activation response to the non-cued 4CRT, the linear increases in regional brain activation associated with increased task complexity and the ability to respond to a cue that were lost in hypoglycaemia alone.

CONCLUSIONS

Caffeine can sustain regional brain activation patterns lost in acute hypoglycaemia, with some restoration of cortical function and enhanced adrenaline responsiveness. A methodology has been established that may help in the development of therapies to protect against severe hypoglycaemia in insulin therapy for patients with diabetes and problematic hypoglycaemia.

Effects of acute antipsychotic treatment on brain activation in first episode psychosis: an fMRI study

This study aimed to assess the neurophysiological effects of acute atypical antipsychotic treatment on cognitive functioning in subjects presenting with a first episode of psychosis. We used functional MRI to examine the modulatory effects of acute psychopharmacological intervention on brain activation during four different cognitive tasks: overt verbal fluency, random movement generation, n-back and a spatial object memory task. Treatment with atypical antipsychotics was associated with alterations in regional activation during each task and also when task demands were manipulated within paradigms. The initial treatment of psychosis with atypical antipsychotics thus appears to be associated with modifications of the neurofunctional correlates of executive and mnemonic functions. These effects need to be considered when interpreting group differences in activation between medicated patients and controls.

Neural responses to dynamic expressions of fear in schizophrenia

Abnormalities in social functioning are a significant feature of schizophrenia. One critical aspect of these abnormalities is the difficulty these individuals have with the recognition of facial emotions, particularly negative expressions such as fear. The present work focuses on fear perception and its relationship to the paranoid symptoms of schizophrenia, specifically, how underlying limbic system structures (i.e. the amygdala) react when probed with dynamic fearful facial expressions. Seven paranoid and eight non-paranoid subjects (all males) with a diagnosis of schizophrenia took part in functional magnetic resonance imaging study (1.5T) examining neural responses to emerging fearful expressions contrasted with dissipating fearful expressions. Subjects viewed emerging and dissipating expressions while completing a gender discrimination task. Their brain activation was compared to that of 10 healthy male subjects. Increased hippocampal activation was seen in the non-paranoid group, while abnormalities in the bilateral amygdalae were observed only in the paranoid individuals. These patterns may represent trait-related hippocampal dysfunction, coupled with state (specifically paranoia) related amygdala abnormalities. The findings are discussed in light of models of paranoia in schizophrenia.

Variable precision registration via wavelets: optimal spatial scales for inter-subject registration of functional MRI

The detection of significantly activated brain regions in multi-subject functional magnetic resonance imaging (fMRI) studies almost invariably entails the coregistration of individual subjects' data in a standard space. Here, we investigate how sensitivity to detect loci of generic activation in such studies may be conditioned by the precision of anatomical registration. We describe a novel algorithm, implemented in the wavelet domain, for inhomogeneous deformation of individual images to match a template. The algorithm matches anatomical features in a coarse-to-fine fashion, first minimising a cost function in terms of relatively coarse spatial features and then proceeding iteratively to match the images in terms of progressively more detailed anatomical features. Applying the method to data acquired from two groups of 12 healthy volunteers (with mean age 27 and 70 years, respectively), during performance of a paired associate learning task, we show that geometrical overlap between template and individual images is monotonically improved, compared to an affine transform, by additional inhomogeneous deformations informed by more detailed features. Likewise, sensitivity to detect activated voxels can be substantially improved, by a factor of 4 or more, if wavelet-mediated deformations informed by medium-sized anatomical features are applied in addition to a preliminary affine transform. However, sensitivity to detect activated voxels was reduced by "over-registering" data or matching anatomical features at the finest scales of the wavelet transform. The benefits of variable precision registration are particularly salient for data acquired in older subjects, which showed evidence of greater inter-subject anatomic variability and generally required more extensive local deformation to achieve a satisfactory match to the template image. We conclude that major benefits in sensitivity to detect functional activation in multi-subject fMRI studies can be attained with an inhomogeneous deformation applied over appropriate spatial scales.

Word retrieval in amyotrophic lateral sclerosis: a functional magnetic resonance imaging study

The cognitive impairment revealed in some non- demented amyotrophic lateral sclerosis (ALS) patients is characterized by executive dysfunction with widely repeated deficits on tests of verbal (letter) fluency. However, conflicting evidence exists of an impairment on other word retrieval tasks, such as confrontation naming, which do not place heavy demands on executive processes. Previous research has demonstrated intact confrontation naming in the presence of verbal fluency deficits, although naming deficits have been described in other studies. In this investigation, functional MRI (fMRI) techniques were employed to explore whether word retrieval deficits and underlying cerebral abnormalities were specific to letter fluency, which are more likely to indicate executive dysfunction, or were also present in confrontation naming, indicating language dysfunction. Twenty-eight non-demented ALS patients were compared with 18 healthy controls. The two groups were matched for age, intelligence quotient, years of education, and anxiety and depression scores. Two compressed-sequence overt fMRI activation paradigms were employed, letter fluency and confrontation naming, which were developed for use with an older and potentially impaired population. In ALS patients relative to controls, the letter fluency fMRI task revealed significantly impaired activation in the middle and inferior frontal gyri and anterior cingulate gyrus, in addition to regions of the parietal and temporal lobes. The confrontation naming fMRI task also revealed impaired activation in less extensive prefrontal regions, including the inferior frontal gyrus and regions of the temporal, parietal and occipital lobes. These changes were present despite matched performance between patients and controls during each activation paradigm. The pattern of dysfunction corresponded to the presence of cognitive deficits on both letter fluency and confrontation naming in the ALS group. This study provides evidence of cerebral abnormalities in ALS in the network of regions involved in language and executive functions. Moreover, the findings further illustrate the heterogeneity of cognitive and cerebral change in ALS.