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Biomedical subjects

C Mahoney

Publications and source records attributed to C Mahoney.

At least 19 recordsLinked to original sources
PubMed2003

Acute effects of cholecystokinin tetrapeptide on brain stem auditory evoked potentials in healthy volunteers.

This study investigated the effects of continuous slow intravenous infusion of cholecystokinin tetrapeptide (CCK-4) on brain stem auditory evoked potentials (BSAEP) in healthy subjects. Twenty-four subjects, 15 females and 9 males, were assigned to infusion with either placebo or CCK-4 in a randomized, double-blind, parallel group design. BSAEPs, mood, physical symptoms, and vital signs were assessed once before infusion and at 10 min and 40 min after the onset of infusion. In the 16 subjects (N = 8, CCK-4; N = 8, placebo) CCK-4, compared to placebo, delayed peak I latency during early infusion, slowed the latencies of peaks III and V, and decreased the amplitude of peak III throughout the infusion. No significant treatment differences were observed with respect to symptoms, mood, or cardiovascular measures. These preliminary findings suggest that CCK-4 may interfere with information processing in the brain stem auditory pathways and that prolonged intravenous CCK-4 administration may be a useful challenge paradigm for investigating CCK's modulatory role on brain stem mechanisms mediating anxiety and panic in humans.

Adolescent↗
PubMed2002

Acute nicotine effects on auditory sensory memory in tacrine-treated and nontreated patients with Alzheimer's disease: an event-related potential study.

The auditory mismatch negativity (MMN) event-related brain potential (ERP) reflects the storage of information in acoustic sensory memory. Thirteen patients with Alzheimer's disease (AD), 6 receiving treatment with the cholinesterase inhibitor, tacrine [tetrahydroaminoacridine (THA)], and 7 receiving no treatment, were administered 2 mg of nicotine polacrilex and placebo. MMNs were recorded with 1- and 3-s interstimulus intervals (ISIs) during pre- and post-placebo/nicotine administration. Amplitudes decreased from pre- to post-placebo recordings in nontreated patients but remained stable in THA-treated patients. Comparison of pre- and post-nicotine MMNs found amplitude increases with nicotine in nontreated but not in THA-treated patients. MMN latencies were shortened by nicotine in both treatment groups. These exploratory findings suggest that nicotine-improved strength of acoustic sensory memory traces and speed of acoustic sensory discrimination in AD are differentially affected by chronic tacrine treatment.

Acoustic Stimulation↗
PubMed2002

Effects of acute nicotine administration on cognitive event-related potentials in tacrine-treated and non-treated patients with Alzheimer's disease.

Earlier studies of cognitive event-related brain potentials (ERPs) reporting diminished amplitudes and delayed latencies of the P300 potential in dementia of the Alzheimer type (DAT), together with independent findings of the P300- and performance-enhancing properties of nicotine in normal adults, stimulated this study to explore the single-dose effects of nicotine on auditory and visual P300s in DAT. Thirteen patients, 6 currently receiving treatment with the cholinesterase inhibitor tacrine (tetrahydroaminoacridine; THA) and the remaining being medication free, were administered 2 mg of nicotine polacrilex under double-blind, randomized, placebo-controlled conditions. Prior to nicotine administration, THA-treated patients exhibited shorter auditory P300 latencies than non-treated patients. Acutely administered nicotine failed to alter auditory P300, but increased the amplitudes of visual P300s in both DAT patient groups. Neither THA treatment nor single-dose nicotine altered behavioural performance in the visual and auditory task paradigms. The results are discussed in relation to nicotinic cholinergic, attentional and cognitive processes in DAT.

Administration, Oral↗
PubMed2002

Nicotine and sensory memory in Alzheimer's disease: an event-related potential study.

The auditory mismatch negativity (MMN) event-related brain potential (ERP) reflects the storage of information in acoustic sensory memory. Thirteen patients with probable Alzheimer's disease (AD), 6 receiving treatment with the cholinesterase inhibitor (ChEI) tacrine (tetrahydroaminoacridine, THA) and 7 receiving no treatment, were administered 2 mg of nicotine polacrilex and placebo. MMNs were recorded with 1- and 3-s interstimulus intervals pre- and postplacebo/nicotine administration. In nontreated patients, amplitudes were decreased from pre- to postplacebo recordings but remained stable in THA-treated patients. Comparison of pre- and postnicotine MMNs found amplitude increases with nicotine in nontreated but not THA-treated patients. MMN latencies were shortened by nicotine in both treatment groups. These exploratory findings suggest that nicotine-improved strength of acoustic sensory memory traces and speed of acoustic sensory discrimination in AD are differentially affected by chronic ChEI treatment.

Acoustic Stimulation↗
PubMed2001

Quantitative EEG in schizophrenia and in response to acute and chronic clozapine treatment.

Topographic quantitative electroencephalographic (EEG) power and frequency indices were collected in 17 treatment refractory, DSM-III diagnosed schizophrenic patients, before and after acute (single dose) and chronic (six weeks) clozapine treatment, as well as in 17 healthy volunteers. Prior to treatment, patients exhibited greater overall absolute theta power, slower mean alpha frequency and elevated absolute delta and total power in anterior regions. Acute dosing increased total spectrum power globally, slow wave power posteriorally, mean alpha frequency and beta power anteriorally and decreased alpha power posteriorally. Six weeks of clozapine treatment significantly reduced clinical ratings of positive and negative symptoms as well as symptoms of global psychopathology. Chronic treatment resulted in EEG slowing as shown by decreases in relative alpha power, mean beta/total spectrum frequency and by widespread increases in absolute total and delta/theta power. The preliminary findings suggest that brain electric profiling may be a promising tool for assessing and understanding the central impact of pharmacotherapeutic interventions in schizophrenia.

Acute Disease↗
PubMed2001

EEG power, frequency, asymmetry and coherence in male depression.

Quantitative electroencephalographic (EEG) power topography has served as a useful tool for investigating brain regional mechanisms underlying affective disorders. In an attempt to examine the role of gender and widen the scope of the measurement probes used in these investigations, the traditional power and inter-hemispheric power ratio indices were supplemented with intra-hemispheric power ratios, mean frequency and both inter and intra-hemispheric coherence indices, in the comparison of depressed male patients and healthy controls. Resting (eyes closed), vigilance controlled EEG recordings from 21 scalp sites were collected from 70 male, unmedicated, unipolar major depressive disorder outpatients and 23 normal control male subjects. Absolute and relative power, frequency, asymmetry and coherence measures derived from spectrally analyzed EEGs were subjected to univariate analyses for group comparisons as well as to discriminant function analysis to examine their utility as classification indices. Compared with controls, patients evidenced greater overall relative beta power and, at bilateral anterior regions, greater absolute beta power and faster mean total spectrum frequency. Inter-hemispheric alpha power asymmetry index differences were noted, with controls exhibiting relatively reduced left hemisphere activation, and widespread reduced delta, theta, alpha and beta coherence indices. Whereas intra-hemispheric theta power asymmetry reduction was exhibited in patients bilaterally at all regions, group differences with intra-hemispheric beta power asymmetry were unilateral, being restricted to the right hemisphere. Discriminant analysis correctly classified 91.3% of the patients and controls. Quantitative EEG measurements in male depression appear to describe a pattern of aberrant inter-hemispheric synchrony/asymmetry and a profile of frontal activation.

Adult↗
PubMed2001

Effects of haloperidol pretreatment on the smoking-induced EEG/mood activation response profile.

This study examined the role of dopamine in modulating the CNS response to cigarette smoking. In a randomized, double-blind, repeated-measures design, quantitative electroencephalographic (EEG) changes and self-reports induced by the smoking of a single cigarette were assessed in 16 smokers following pretreatment with placebo and a dopamine antagonist, haloperidol (2 mg). Following placebo pretreatment, absolute (muV) and relative (%) amplitudes in slow-frequency bands (delta, theta, alpha1) were reduced and absolute and relative amplitudes in fast-frequency bands (alpha2, beta) were increased following cigarette smoking as compared to sham smoking. Haloperidol pretreatment inhibited the smoking-induced increase in absolute beta frequency. Self-ratings indicated that cigarette smoking induced increases in alertness, contentedness and calmness but not euphoria, and reduced cigarette cravings as compared to the sham smoking conditions. Smoking-induced, alpha2 increments were associated with increases in alertness and decreases in euphoria while beta increments were associated with increased calmness. Smoking-related self-ratings of mood and cigarette acceptability were not altered by haloperidol, but subjects were less content overall in the haloperidol condition as compared to placebo. Discussion of these results focuses on transmitter systems and their relationship to neuro-electric and behavioural activities associated with the smoking habit.

Adult↗
PubMed2001

Glucose and glucoregulatory modulation of memory scanning, event-related potentials and EEG in elderly subjects.

Endogenous P300b event-related potential (ERP) and behavioral performance measures, extracted during a visual memory scanning task, and spectral indices of resting electroencephalographic (EEG) activity, were assessed in 12 healthy elderly adults before and after double-blind oral administration of a placebo or glucose (50 mg) beverage. Glucoregulation was estimated by deriving a recovery index to categorize subjects as having better (BR) or poorer (PR) blood glucose recovery. Although glucoregulatory status did not impact on EEG or task performance, PR subjects exhibited reduced P300b areas relative to BR subjects prior to beverage administration. Glucose did not alter P300b or memory scanning performance but, regardless of glucoregulatory status, it increased the EEG power in the slow alpha frequency band. The study results suggest that peripheral glucoregulation can influence neuroelectric measures of cognition and that the acute ingestion of glucose can modulate central arousal processes.

Aged↗
PubMed2001

A preliminary study of mental and physical practice on the kayak wet exit skill.

Outdoor activities and high-risk water sports often create anxiety in participants who feel concern about danger. Relaxation and imagery, often used to enhance training, can improve performance of skills in a variety of sports. The aim of this study was to establish whether Mental Practice, Physical Practice, Combined Mental and Physical Practice, or No Practice would affect the acquisition of skill for a kayak wet exit. 60 postprimary girls aged 11-16 yr., competent swimmers but without previous experience in kayaking, gave their informed consent to be in the study. Each participant was randomly assigned to one of the four experimental groups. Following their practice periods, each group performed three kayak wet exit attempts (unseen by others); these were videotaped for later analysis by an observer. The participant and an independent observer, who was blind to the allocation of practice group, then used a 6-point rating scale to assess each performance. Participants' and the observer's ratings were analysed by separate Kruskal-Wallis one-way analysis of variance which indicated a significant practice effect. Subsequent chi-squared tests indicated significantly different distributions of groups, showing Physical Practice superior to No Practice and Mental Practice. While physical practice remained effective in improving technique, combinations of mental and physical practice were better than no practice.

Adolescent↗
PubMed2001

Quantitative electroencephalography in Alzheimer's disease: comparison with a control group, population norms and mental status.

OBJECTIVE: Given that quantitative electroencephalography (EEG) has repeatedly shown excessive slow wave activity in dementia of the Alzheimer type (DAT) that increases with disease progression, we assessed the clinical utility of this tool by comparing various approaches used to assess slowing. DESIGN: Cross-sectional study comparing quantitative EEG data from patients with DAT with normative data from an elderly control group and from EEG norms derived from a large population. PARTICIPANTS: 35 subjects diagnosed with probable DAT and 30 elderly controls. OUTCOME MEASURE: EEG recorded from 21 scalp sites of each patient and elderly control during vigilance-controlled, eyes-closed, resting conditions was spectrally analyzed to yield measures of absolute and relative power in delta, theta, alpha and beta bands and indices of mean alpha band and total band frequency. RESULTS: Group comparisons of raw or age-regressed z-score population normative values yielded different profiles with respect to direction of frequency band changes, regional topography and clinical rating correlations, but both procedures evidenced overall patterns of EEG slowing in DAT. However, both methodologies yielded only modest (75%) classification rates. CONCLUSION: Quantitative EEG remains a valuable research tool but, as yet, an unproven diagnostic tool, for DAT.

Aged↗
PubMed2000

Pre-treatment EEG and it's relationship to depression severity and paroxetine treatment outcome.

An array of variables have been assessed as potential early predictors of antidepressant response in depressed patients. This exploratory study examined the relationship of clinical outcome, following pharmacotherapeutic treatment, with quantitative electroencephalographic (EEG) features assessed prior to treatment onset. In 70 major affective disorder patients, pre-treatment spectrum-analysed topographic EEG indices (absolute power, relative power, mean frequency, inter-hemispheric power asymmetry and coherence for 4 frequency bands) were assessed in relation to baseline HAM-D ratings and HAM-D rating changes following 6 weeks of open-label paroxetine treatment. EEG slow wave (theta) activities were positively correlated with depression ratings prior to treatment. Of the patients (n = 51) completing treatment, 80% evidenced a >50% reduction in HAM-D ratings. Improved rating changes in general were found to be negatively related to slow (delta and theta) wave activity and positively related to fast (beta) activity at frontal recording sites. Findings are discussed in relation to the neurochemistry and neurobiology of depressive disorders.

Adult↗
PubMed2000

Acute nicotine administration in Alzheimer's disease: an exploratory EEG study.

Previous findings of cognitive deficits and EEG slowing in Alzheimer's patients, together with independent reports of the performance enhancing and electrocortical activating properties of nicotine in normal adults, stimulated this study to examine the acute effects of nicotine on spectrum-analyzed EEG in patients with dementia of the Alzheimer type (DAT). Thirteen patients, 6 currently receiving cholinesterase inhibitor treatment and the remaining being medication free, were administered 2 mg of nicotine polacrilex under randomized, placebo-controlled conditions. Compared to age-regressed EEG norms, the pretreatment EEG spectrums of patients in general were characterized by excessive slow (delta and theta)-wave power, diminished fast (alpha and beta)-wave power and slow mean alpha and total band frequencies. Although postnicotine EEG indices remained within the abnormal range, nicotine, compared to placebo, significantly shifted EEG towards normal values by reducing slow wave (relative delta and theta) power and augmenting fast (relative alpha-1, alpha-2, beta-1) wave power. No differences were observed between treated and nontreated patients in response to nicotine. The results are discussed in relation to cholinergic and brain arousal systems and their relationship to cognitive processes.

Administration, Oral↗
PubMed2000

Electroencephalographic coherence in Alzheimer's disease: comparisons with a control group and population norms.

Previous research from independent laboratories has shown reduced electroencephalographic coherence in patients diagnosed with dementia of the Alzheimer type (DAT). This study added to this work by comparing interhemispheric and intrahemispheric coherence in nonmedicated DAT patients (n = 35) with that of a normal control group (n = 30), as well as with a data bank of population norms. Raw and Z-score transformed values showed reduced coherence, interhemispherically (in delta, theta, alpha, and beta bands) and intrahemispherically (delta and theta bands) in DAT patients with both comparison procedures. Discriminant analysis correctly classified 73% to 75% of patients. The results are discussed in relation to earlier research, "trait" versus "state" factors, the cholinergic system, and cognitive processes in dementia.

Aged↗
PubMed2000

EEG hemispheric asymmetry as a predictor and correlate of short-term response to clozapine treatment in schizophrenia.

In search of early neuroleptic response predictors in schizophrenia, functional interhemispheric and intrahemispheric asymmetry indices, derived from spectrally analyzed resting electroencephalographic (EEG) activity, were examined in 17 schizophrenic patients prior to open label treatment with the atypical neuroleptic clozapine. Compared to EEG asymmetry indices derived from a normative data bank, patients exhibited significant interhemispheric (left greater than right) and intrahemispheric (anterior greater than posterior) deviations in delta, theta, alpha and beta frequency bands. Intrahemispheric indices were positively correlated with clinical ratings of positive symptoms and global psychopathology. Clozapine-induced improvements in positive and negative symptoms and global psychopathology symptom ratings were related to pretreatment intrahemispheric asymmetry only, with relationships varying with symptom, recording region and frequency band. The results are discussed in relation to the neurobiology of schizophrenia and the utility of EEG as an informative predictor of treatment response.

Adult↗
PubMed2000

Pharmaco-EEG test dose response predicts cholinesterase inhibitor treatment outcome in Alzheimer's disease.

Previous investigations have indicated that a single dose pharmaco-EEG may predict the outcome of 4-7 weeks of tetrahydroaminoacridine (THA) treatment in dementia of the Alzheimer type (DAT). This open trial study further examined the relationship of quantitative EEG in relation to treatment response by assessing 24 probable DAT patients at baseline, 2 h after their first oral dose (30 mg), and after 12 weeks of THA treatment. Compared to EEG norms, patients, in general, evidenced EEG slowing, as shown by excessive slow (theta) and diminished fast (alpha and beta) wave power as well as reduced mean frequencies which were present prior to treatment as well as at the end of treatment. The EEG of patients exhibiting stable or improved scores on the Mini-Mental State examination (MMSE) at 12 weeks showed a significantly faster baseline mean alpha frequency as well as a significant reduction in relative theta power following the single THA test dose compared to deteriorated patients. A discriminant analysis using test dose response EEG variables correctly classified 75-79% of these two patient groups, suggesting that this procedure may be a useful approach for optimizing patient selection for antidementia treatments.

Aged↗
PubMed1999

Event-related potentials in schizophrenic patients during a degraded stimulus version of the visual continuous performance task.

Previous studies of the auditory P300 event-related potential (ERP) have reported smaller amplitudes in chronic schizophrenics but similar consistencies have not been observed with visual P300s. This study examined P300s in symptomatically stable, medicated, chronic schizophrenics (n = 14) and normal controls (n = 14) performing a visual continuous performance task utilizing degraded stimuli to burden encoding processes. Performance analysis found slower response times, fewer target detections and more false alarms in patients than in controls. Analysis of ERPs showed P300 amplitudes of schizophrenics to be significantly smaller than those of controls and, unlike controls, schizophrenics failed to exhibit significant target vs. non-target P300 amplitude differences. Discriminant analysis indicated target and non-target midline (Fz, Cz, Pz) P300 amplitudes together correctly classified all patients and controls. Exploratory topographic analysis indicated that P300 amplitudes were not asymmetrical in patients, as has been observed with auditory P300s, and, unlike the performance measures, the P300s did not correlate with the patient's positive or negative symptom ratings. The implications of these findings are described in relation to attentional disturbances and trait versus state issues in schizophrenics.

Adult↗
PubMed1999

Transdermal nicotine: single dose effects on mood, EEG, performance, and event-related potentials.

A 21-mg dose of nicotine was administered transdermally to 16 overnight smoking-deprived smokers in a double-blind, placebo-controlled design. Mood ratings, electroencephalography (EEG), behavioral performance and event-related potential (ERP: P300) indices of attention and information processing speed were assessed before and 4 h after placebo/nicotine treatment. Although nicotine, relative to placebo, failed to alter mood, it increased absolute and relative power indices of EEG arousal, shortened reaction times, and increased P300 amplitudes. The results are discussed in relation to nicotine's actions on cholinergic transmission and its role in smoking behavior.

Administration, Cutaneous↗