Cognitive performance in hypertensive and normotensive older subjects

Longitudinal studies suggest that hypertension in midlife is associated with cognitive impairment in later life. Cross-sectional studies are difficult to interpret because blood pressure can change with onset of dementia and the inclusion of subjects on treatment and with hypertensive end-organ damage can make analysis difficult. We examined cognitive performance in hypertensive and normotensive subjects without dementia or stroke >/=70 years of age. Cognitive performance was determined with the use of a computerized assessment battery in 107 untreated hypertensives (55 women, age 76+/-4 years, blood pressure, 164+/-9/89+/-7; range, 138 to 179/68 to 99 mm Hg) and 116 normotensives (51 female, age 76+/-4 years, 131+/-10/74+/-7; 108 to 149/60 to 89 mm Hg). Older subjects with hypertension were significantly slower in all tests (reaction time, milliseconds; simple, 346+/-100 versus 318+/-56, P<0.05; memory scanning, 867+/-243 versus 789+/-159, P<0.01; immediate word recognition, 947+/-261 versus 886+/-192, P<0.05; and delayed word recognition, 937+/-230 versus 856+/-184, P<0.05; picture recognition, 952+/-184 versus 894+/-137, P<0.01; spatial memory, 1390+/-439 versus 1258+/-394, P<0.01; excepting choice reaction time, 510+/-75 versus 498+/-72, P=0.08). Accuracy was also impaired in tests of number vigilance, 99.2+/-2.5% versus 99.9+/-0.9, P<0.01; delayed word recognition, 83.5+/-16 versus 87.9+/-9.8, P<0.01; and spatial memory 64+/-32 versus 79+/-20, P<0.001. Hypertension in older subjects is associated with impaired cognition in a broad range of areas in the absence of clinically evident target organ damage.

Quantification and characterization of fluctuating cognition in dementia with Lewy bodies and Alzheimer's disease

Fluctuating cognition (FC) is a common and important symptom in dementia, particularly dementia with Lewy bodies (DLB), although it has not been empirically quantified or characterised. Forty subjects (15 DLB, 15 AD, 10 elderly controls) were evaluated using a clinical FC severity scale, as well as receiving measures of variability in attentional performance and slow EEG rhythms across 90 s, 1 h and 1 week. DLB patients had significantly more severe FC and more severe variability in attentional and slow electrocortical measures than either AD patients or normal controls in all time frames. Attentional and EEG variability also correlated significantly with independent clinical ratings of FC. Clinical quantification and measures of attention and EEG variability can therefore make an important and standardised contribution to the assessment of FC in dementia, facilitating future treatment studies with important implications for the potential causative mechanisms and differential diagnosis.

The Clinician Assessment of Fluctuation and the One Day Fluctuation Assessment Scale. Two methods to assess fluctuating confusion in dementia

BACKGROUND

The identification of fluctuating confusion is central to improving the differential diagnosis of the common dementias.

AIMS

To determine the value of two rating scales to measure fluctuating confusion.

METHOD

The agreement between the clinician-rated scale and the scale completed by a non-clinician was determined. Correlations between the two scales were calculated; variability in attention was calculated on a computerised cognitive assessment and variability in delta rhythm on an electroencephalogram (EEG).

RESULTS

The Clinician Assessment of Fluctuation and the computerised cognitive assessment were completed for 155 patients (61 Alzheimer's disease, 37 dementia with Lewy bodies, 22 vascular dementia, 35 elderly controls). A subgroup (n = 40) received a further evaluation using the One Day Fluctuation Assessment Scale and an EEG. The two scales correlated significantly with each other, and with the neuropsychological and electrophysiological measures of fluctuation.

CONCLUSIONS

Both scales are useful instruments for the clinical assessment of fluctuation in dementia.

Quantifying fluctuation in dementia with Lewy bodies, Alzheimer's disease, and vascular dementia

BACKGROUND

Case reports and clinical observations suggest that fluctuating cognition (FC) is common in the major dementias, particularly dementia with Lewy bodies (DLB), where it is one of three core clinical diagnostic features.

OBJECTIVES

To examine the frequency, characteristics, and diagnostic utility of FC in dementia using clinical, attentional, and EEG markers.

METHOD

- A total of 155 subjects (61 with AD, 37 with DLB, 22 with vascular dementia [VaD], 35 elderly controls) received clinical evaluation for FC using a semiquantified measure applied by experienced clinicians and 90-second cognitive choice reaction time (CRT) and vigilance reaction time (VIGRT) trials. Forty subjects also received an evaluation of mean EEG frequency across 90 seconds.

RESULTS

Patients with DLB had a greater prevalence and severity of FC than did patients with AD or VaD rated using clinical, attentional, and EEG measures. The 90-second cognitive and EEG trials demonstrated that FC occurs on a second-to-second basis in patients with DLB. Patients with VaD had a higher prevalence of FC than did those with AD, although the profile of FC was different from that expressed by DLB cases. Optimal cutoff values on the clinical scale achieved good discrimination between the dementia groups (sensitivity 81%, specificity 92%, DLB versus AD; sensitivity 81%, specificity 82%, DLB versus VaD; sensitivity 64%, specificity 77%, VaD versus AD).

CONCLUSION

Standardized assessment methods demonstrate that FC is significantly more common and severe in DLB than in other major dementias. The periodicity of FC is different in DLB and VaD cases, with important implications for the underlying causal mechanisms and for differential diagnosis.

Tiagabine: absence of kinetic or dynamic interactions with ethanol

Tiagabine is a new antiepileptic drug that inhibits the uptake of gamma-aminobutyric acid into neurons and glia. This double-blind, placebo-controlled study investigated the effect of multiple doses of tiagabine on the adverse cognitive effects produced by a single dose of ethanol in 20 healthy volunteers. The effects of each drug on the pharmaco-kinetics of the other were also determined. Compared with placebo, tiagabine produced no statistically significant effects on digit vigilance speed (primary assessment variable) or accuracy, choice reaction time, immediate or delayed word recall, delayed word recognition speed or sensitivity, visual tracking, body sway, or subjective measures of alertness, calmness, and contentment. There was no evidence of a pharmacodynamic interaction between tiagabine and ethanol with respect to these variables. The pharmacokinetic parameters of tiagabine and ethanol (maximum plasma concentration [Cmax], time to Cmax and area under the plasma concentration-time curve) were unchanged during concomitant administration. Adverse events, which mainly affected the central nervous system, occurred with a similar incidence during tiagabine and placebo administration and were more common after the administration of ethanol. There appears to be no need for additional caution regarding driving or operating machinery when ethanol is administered to patients taking tiagabine.

The cognitive and psychomotor effects of morphine in healthy subjects: a randomized controlled trial of repeated (four) oral doses of dextropropoxyphene, morphine, lorazepam and placebo

Ten healthy subjects (four male) of mean age 31 years (range 25-40) took part in a randomized double-blind four-way crossover study to examine the cognitive and psychomotor effects of repeated oral doses of dextropropoxyphene and morphine. Four treatments were compared: dextropropoxyphene napsylate 100 mg, morphine sulphate 10 mg, lorazepam 0.5 mg and placebo. Four doses of each drug were given at 4-h intervals to each subject on four separate study days at least 1 week apart. Cognitive function was assessed using choice reaction time, number vigilance, memory scanning, immediate and delayed word recall, word recognition, picture recognition, critical flicker fusion threshold (CFFT) and subjective measures of alertness, calmness and contentment. Lorazepam impaired the speed of responding on all tasks in which speed was recorded (except digit vigilance) and increased subjective ratings of calmness. Morphine had one major effect, which was to increase the accuracy of responding on the choice reaction time task, at every assessment. Morphine produced some sporadic effects in other tests and an increase in subjective calmness. Dextropropoxyphene impaired performance on choice reaction time and picture recognition. These data show that oral morphine may enhance performance in some measures of cognitive function, whereas dextropropoxyphene (in usual therapeutic doses) seems more likely to cause impairment. Neither opioid has substantial effects on cognition and psychomotor function compared with lorazepam.

Cognitive properties of sedation agents: comparison of the effects of nitrous oxide and midazolam on memory and mood

OBJECTIVES

To compare the effects of nitrous oxide and midazolam on cognition and mood.

DESIGN

A three-way, counterbalanced, cross-over study, using patients receiving conscious sedation for routine dental treatment.

METHODS

On each of three separate visits, patients performed a computerised test battery to determine baseline cognitive performance. Then, following administration of either midazolam, nitrous oxide, or no drug, patients re-performed the test battery. Finally, patients completed visual analogue scales assessing their subjective mood state.

RESULTS

Relative to baseline performance, midazolam administration produced significantly slower reaction times compared with nitrous oxide and no-drug conditions. Furthermore, patients receiving midazolam were impaired in accuracy relative to the other conditions on many of the cognitive tasks, particularly those assessing the recall of information. Patient performance in nitrous oxide and control conditions did not significantly differ. These results could not be explained by differences in mood between the conditions, as subjective mood ratings during midazolam or nitrous oxide administration were very similar.

CONCLUSIONS

It is important for clinicians to be aware that peri-operative recall of information is reduced in patients who have undergone midazolam sedation. This is an advantage for patients who are anxious, and do not wish to be aware of the operative treatment being performed. However, as the cognitive impairment is enduring, an adult escort and written post-operative instructions should be mandatory for midazolam sedation patients. In contrast, the use of nitrous oxide sedation does not significantly impair higher cognitive tasks and thus patients receiving nitrous oxide sedation can resume normal activities in the post-operative period.

Cognitive performance, hyperoxia, and heart rate following oxygen administration in healthy young adults

It was recently established that supplemental oxygen administration significantly enhances memory formation in healthy young adults. In the present study, a double-blind, placebo-controled design was employed to assess the cognitive and physiological effects of subjects' inspiration of oxygen or air (control) prior to undergoing simple memory and reaction-time tasks. Arterial blood oxygen saturation and heart rate were monitored during each of six phases of the experiment, corresponding to baseline, gas inhalation, word presentation, reaction time, distractor and word recall, respectively. The results confirm that oxygen administration significantly enhances cognitive performance above that seen in the air inhalation condition. Subjects who received oxygen recalled more words and had faster reaction times. Moreover, compared to participants who inhaled air, they exhibited significant hyperoxia during gas administration, word presentation, and the reaction-time task, but not at other phases of the experiment. Compared to baseline, heart rate was significantly elevated during the word presentation, reaction-time, and distractor tasks in both the air and oxygen groups. In the oxygen group, significant correlations were found between changes in oxygen saturation and cognitive performance. In the air group, greater changes in heart rate were associated with more improved cognitive performance. These results are discussed in the context of cognitive demand and metabolic supply. It is suggested that under periods of cognitive demand a number of physiological responses are brought into play that serve to increase the delivery of metabolic substrates to active neural tissue. These mechanisms can be supplemented by increased availability of circulating blood oxygen, resulting in an augmentation of cognitive performance. Heart rate reactivity and the capacity for increased blood oxygen appear to be important physiological individual differences mediating these phenomena.

A comparison of the effects of olanzapine, haloperidol and placebo on cognitive and psychomotor functions in healthy elderly volunteers

The cognitive and psychomotor effects of olanzapine (3 mg) were compared with haloperidol (3 mg) and placebo in a double-blind, cross-over study. Fourteen healthy elderly volunteers (>65 years) were randomized to receive once daily medication for 4 days with a 16-day interval between treatment periods. Assessments of attention, memory and motor control were made prior to dosing on each day, at 2, 4, 6 and 8 h after dosing on days 1 and 4, and at 24 and 48 h following the last dose. On day 1, detectable impairment was observed at all time points in both groups. On day 4, haloperidol treated subjects showed increased impairment compared with day 1 and this was sustained throughout the 48 h of testing. Olanzapine treated subjects showed reduced day 4 deficit (compared with day 1), with no significant difference from placebo beyond 6 h post dose. These results suggest that both haloperidol and olanzapine have a measurable initial effect on cognitive and psychomotor function in elderly volunteers. However, acute effects associated with olanzapine decrease with repeated dosing and show substantial adaptation within 4 days. In contrast, effects seen with haloperidol are sustained and increase with repeated dosing over the same period.

Effect of a 915-MHz simulated mobile phone signal on cognitive function in man

PURPOSE

To examine whether a simulated mobile telephone transmission at 915 MHz has an effect on cognitive function in man.

MATERIALS AND METHODS

Thirty-six subjects in two groups were each given two training sessions and then three test sessions in a randomized three-way cross-over design. About 1 W mean power at 915 MHz from a quarter-wave antenna mounted on a physical copy of an analogue phone, as a sine wave, or modulated at 217 Hz with 12.5% duty cycle, or no power, was applied to the left squamous temple region of the subjects while they undertook a series of cognitive function tests lasting approximately 25-30 min. The second group was investigated for sleep, consumption of alcohol and beverages, and any other substances that might affect performance.

RESULTS

In both groups, the only test affected was the choice reaction time and this showed as an increase in speed (a decrease in reaction time). There were no changes in word, number or picture recall, or in spatial memory. While an effect of visit-order was evident suggesting a learning effect of repeat tests, the design of the study allowed for this. Additionally, there was no systematic error introduced as a result of consumption of substances or sleep time.

CONCLUSIONS

There was evidence of an increase in responsiveness, strongly in the analogue and less in the digital simulation, in choice reaction time. This could be associated with an effect on the angular gyrus that acts as an interface between the visual and speech centres and which lies directly under and on the same side as the antenna. Such an effect could be consistent with mild localized heating, or possibly a non-thermal response, which is nevertheless power-dependent.

Oxygen and cognitive performance: the temporal relationship between hyperoxia and enhanced memory

Oxygen administration coinciding with word presentation enhances word recall in humans, suggesting that elevated levels of circulating blood oxygen may be available to neural memory consolidation processes. This double-blind experiment examined the relationship between blood oxygen levels and cognitive performance when oxygen was inspired for 2 min at different times relative to a simple word recall task, forward digit span and backward digit span. Transient hyperoxia, measured by haemoglobin-bound oxygen, was evident following oxygen inspiration. Neither forward nor backward digit span was affected by oxygen administration. Word recall (12 min following word presentation) was enhanced when oxygen was administered 5 min prior to, immediately before or immediately following word presentation; but not 10 min prior to, 5 min following nor 10 min following, word presentation. These data suggest that oxygen administration can selectively enhance aspects of cognitive performance and support a hypothesis whereby supplemental blood oxygen is sequestered by neural mechanisms involved in memory consolidation.

Oxygen administration selectively enhances cognitive performance in healthy young adults: a placebo-controlled double-blind crossover study

It was recently demonstrated that oxygen administration can improve performance on a simple word recall task in healthy young adults. This study was aimed at determining the impact of various durations of oxygen administration on a wider range of cognitive measures. This was achieved using the Cognitive Drug Research computerised test battery, and employing a double-blind, placebo-controlled crossover design. Over a period of 7 weeks, 20 participants were trained and subsequently assessed on the test battery under several durations of oxygen inhalation; air administered in an identical fashion served as a control. The results provided support for our earlier work in that increases were found in both immediate and delayed word recall. In addition, oxygen administration significantly improved performance on several measures of attention and vigilance. Simple reaction time, choice reaction time, digit vigilance reaction time and picture recognition reaction time were improved in a manner which depended on the duration of oxygen inspired. With the exception of word recall, no significant improvements were found for any measure of accuracy, nor were word recognition, digit memory scanning, or spatial memory improved. These results are discussed in the context of stages of information processing and are consistent with the hypothesis that cognitive performance is "fuel-limited" and can be differentially augmented by increasing the availability of the brain's metabolic resources.

Cognitive performance in recreational users of MDMA of 'ecstasy': evidence for memory deficits

Cognitive task performance was assessed in three groups of young people: 10 regular users of 3,4-methylenedioxymethamphetamine (MDMA) who had taken 'ecstasy' 10 times or more; 10 novice MDMA users who had taken 'ecstasy' one to nine times; and 10 control subjects who had never taken MDMA. A computerized battery of cognitive tasks (Cognitive Drug Research system) was undertaken on a day when subjects were drug free. Performance on the response speed and vigilance measures (simple reaction time, choice reaction time, number vigilance), was similar across the three subgroups. However on immediate word recall and delayed word recall, both groups of MDMA users recalled significantly less words than controls. Animal research has shown that MDMA can lead to serotonergic neurodegeneration, particularly in the hippocampus and frontal cortex. Although the design of this study was far from ideal, these data are consistent with other findings of memory decrements in recreational MDMA users, possibly caused by serotonergic neurotoxicity.

Scopolamine-induced cognitive impairment as a predictor of cognitive decline in healthy elderly volunteers: a 6-year follow-up

OBJECTIVE

To determine if scopolamine-induced cognitive impairment in healthy elderly people predicts cognitive decline 6 years later.

DESIGN

Prospective cohort study.

SETTING

Elderly care research unit.

PARTICIPANTS

Healthy elderly people who were part of a volunteer panel of research subjects.

INTERVENTIONS

Scopolamine 0.2 mg administered subcutaneously at baseline.

MAIN OUTCOME MEASURES

Cognitive drug research computerized cognitive testing battery pre- and post-scopolamine, with repeat testing over 6 years later.

MAIN RESULTS

16/24 subjects were retested. Although marked decrements in cognitive functioning were seen with scopolamine, there was little change in performance over 6 years, and no significant association was seen between scopolamine-induced decrement and change over time.

CONCLUSIONS

The scopolamine challenge test is not likely to play a role in the preclinical diagnosis of Alzheimer's disease.

The psychological and psychiatric effects of rIL-2 therapy: a controlled clinical trial

It has been suggested that recombinant interleukin-2 (rIL-2) may cause pyschological and psychiatric problems, although the effects of rIL-2 on its own have not been well documented. To evaluate these effects, 17 patients with advanced colorectal cancer took part in a randomised, parallel group study of rIL-2 with chemotherapy (5-fluorouracil and leucovorin) versus chemotherapy alone. Patients were assessed regularly by means of various psychometric tests including the Hospital Anxiety and Depression Scale, the Mood Rating Scale, the Mini-Mental State Examination, the Digit Symbol Substitution Test, the Trail-Making Test and the Benton Revised Visual Retention Test. Rigorous discontinuation criteria were applied to ensure that the effect of time-related variables did not influence the results. Compared with patients who were given chemotherapy alone, patients receiving immunochemotherapy reported reduced energy, impaired confidence, higher depressed mood and more confusion. Immunochemotherapy was rated as more distressing than chemotherapy alone and patients reported a greater incidence of appetite impairment, weight loss, poor concentration and fever. Cognitive assessments indicated that brain dysfunction can be caused by rIL-2. Compared with the control group, patients receiving immunochemotherapy showed significant impairment on Trail Making Test B and the Digit Symbol Substitution Test. One patient developed repeated transient psychotic episodes associated with rIL-2 infusions and another regularly became confused. These effects were not due to sleep deprivation or pyrexia. Treatment with rIL-2 should not be discarded on psychosocial grounds, although in each case the psychological morbidity and adverse effects on quality of life need to be balanced carefully against potential therapeutic benefits.

Moxonidine and cognitive function: interactions with moclobemide and lorazepam

OBJECTIVE

Moxonidine represents a new generation of centrally acting antihypertensive drugs. It binds to I1-imidazoline receptors and exerts its antihypertensive activity through a reduction in systemic vascular resistance, while cardiac output remains unchanged or even increases slightly. Moxonidine is prescribed for the treatment of mild to moderate hypertension. Typical doses are 0.4 to 2.0 mg given as one dose in the morning or as divided doses in the morning and evening.

METHODS

The effects of moxonidine 0.4 mg once daily in combination with moclobemide or lorazepam were investigated in two, double-blind, randomised, placebo-controlled, two-way crossover studies in a total of 48 healthy volunteers. Safety assessments were made in each study and included pre- and post-study measurement of blood pressure, heart rate, ECG, haematology, blood biochemistry, and urinalysis, and recording of adverse events.

RESULTS

In the first study, moxonidine alone was found to produce small but statistically significant impairments of vigilance detection speed at 4 h and 6 h. Lowering of subjective alertness was also observed. Repeat dosing with moxonidine produced an impairment of memory scanning performance. These findings were not reproduced in the second study, in which moxonidine alone produced an improvement in immediate word recall at 4 h and 6 h. No interactions were observed when moxonidine was co-administered with moclobemide. Moxonidine, when co-administered with lorazepam, produced interactions with three tasks requiring high levels of attention: choice, simple reaction time and digit vigilance performance; memory tasks; immediate word recall, delayed word recall accuracy; and visual tracking. A total of 47 adverse events were reported in study 1. Moxonidine produced a slight decrease of systolic and diastolic blood pressure. In study 2, a total of 55 adverse events were reported. In both trials, the most frequently reported events were tiredness and dryness of mouth, the latter occurring only under the moxonidine treatment. There were no clinically relevant changes observed in blood pressure, pulse rate, and laboratory tests in either study, nor was there any evidence of any interaction between moxonidine and either moclobemide or lorazepam.

CONCLUSION

Moxonidine was found to be safe and well tolerated in healthy volunteers. However, the impairments on attentional tasks were greater when moxonidine was co-administered with lorazepam 1 mg. These effects should be considered when moxonidine is codosed with lorazepam, although they were smaller than would have been produced by a single dose of lorazepam 2 mg.

Incremental dosage of the new antipsychotic mazapertine induces tolerance to cardiovascular and cognitive effects in healthy men

OBJECTIVES

Mazapertine is a structurally novel antipsychotic compound with high affinity for D2, D3, 5-HT1a, and alpha 1 receptors. The objectives were to determine whether tolerance to orthostatic hypotension caused by this compound could be induced by slowly increasing the dose administered and to investigate its effect on cognitive and motor functions.

METHODS

Thirteen healthy male subjects received incremental oral doses of mazapertine (from 5 to 50 mg over 7 days; n = 10) or placebo (n = 3) in part I and single doses in parts II (20 or 30 mg or placebo) and III (40 mg or placebo) in a double-blind fashion. Blood pressure, heart rate, cardiac hemodynamics, cognitive functions, and occurrence of acute extrapyramidal symptoms were investigated.

RESULTS

Mazapertine appears to be safe and well tolerated when administered orally for 7 days to normal healthy men. No accumulation of serum prolactin occurred after multiple dosing, suggesting limited potential for inducing galactorrhea. The drug was rapidly absorbed, and kinetics appeared to be dose dependent, without accumulation. The elimination half-life was about 5 to 10 hours. No evidence of any positive or negative cognitive effects could be detected. Mild motor symptoms were observed only at high doses (not statistically significant). Mazapertine had a minimal effect on cardiac output and stroke volume. Tolerance to hypotension could be induced by slowly increasing the dose administered.

CONCLUSIONS

Mazapertine is well tolerated when administered orally for seven days, and tolerance to hypotension can be induced by slowly increasing the dose administered. Therefore, nothing precludes further clinical testing on patients with schizophrenia.

Absence of effect of sertraline on the pharmacokinetics and pharmacodynamics of phenytoin

A double-blind, randomized, placebo-controlled study assessed the effects of sertraline on the pharmacokinetics and pharmacodynamics of phenytoin in 30 healthy male volunteers.

METHOD

All subjects received phenytoin throughout the study. The dose of phenytoin was 100 mg three times daily; steady-state trough plasma phenytoin concentrations were determined on Day 6. Concurrent treatment with sertraline (16 subjects) or placebo (13 subjects) was initiated on Day 8 and continued throughout the study in those subjects whose trough plasma phenytoin concentrations were between 5 and 20 micrograms/mL. The dose of sertraline was increased from 50 to 200 mg/day over 7 days; the 200-mg dose was then administered for 10 days. The plasma phenytoin concentration-time profile was determined on Day 7 before the start of sertraline or placebo dosing and at the end of dosing on Day 24. Psychometric testing was done before and after dosing on Days 0, 7, and 24.

RESULTS

There were no significant differences between the sertraline group and the placebo group in the pharmacokinetic parameters of phenytoin. In addition, there was no indication that administration of phenytoin alone or concomitant administration of phenytoin and sertraline impaired cognitive function. Treatment-related side effects, primarily headache and nausea, were reported in 8 of 16 sertraline subjects and in 5 of 13 placebo subjects. Two subjects in the sertraline group withdrew because of side effects (rash), and 3 subjects in the placebo group withdrew because of side effects (rash and headache).

CONCLUSION

High dosages of setraline did not affect the pharmacokinetics or the pharmacodynamics of phenytoin in ths study performed in healthy volunteers.

Absence of effect of sertraline on time-based sensitization of cognitive impairment with haloperidol

This double-blind, randomized, placebo-controlled study evaluated the effects of haloperidol alone and haloperidol plus sertraline on cognitive and psychomotor function in 24 healthy male subjects.

METHOD

All subjects received placebo on Day 1 and haloperidol 2 mg on Days 2 and 25. From Days 9 to 25, subjects were randomly assigned to either sertraline (12 subjects) or placebo (12 subjects); the sertraline dose was titrated from 50 to 200 mg/day from Days 9 to 16, and remained at 200 mg/day for the final 10 days of the drug administration period. Cognitive function testing was performed before dosing and over a 24-hour period after dosing on Days 1, 2, and 25.

RESULTS

Impairment of cognitive function was observed 6 to 8 hours after administration of haloperidol on Day 2 but was not evident 23 hours after dosing. When single-dose haloperidol was given again 25 days later, greater impairment with earlier onset was noted in several tests in both treatment groups, suggesting enhancement of this effect. There was no indication that sertraline exacerbated the impairment produced by haloperidol since an equivalent effect also occurred in the placebo group. Three subjects (2 on sertraline and 1 on placebo) withdrew from the study because of side effects. Ten subjects in each group reported side effects related to treatment. The side effect profiles of sertraline and of placebo were similar.

CONCLUSION

Haloperidol produced a clear profile of cognitive impairment that was not worsened by concomitant sertraline administration.

Absence of a sertraline-mediated effect on the pharmacokinetics and pharmacodynamics of carbamazepine

A double-blind, randomized, placebo-controlled study was conducted in 14 healthy male volunteers to assess the effects of sertraline on the pharmacokinetics and pharmacodynamics of carbamazepine.

METHOD

Subjects received carbamazepine 200 mg once daily for 2 days and every 12 hours thereafter. On Days 16 to 32, subjects also received either sertraline or placebo daily. The dose of sertraline was increased from 50 to 200 mg daily over 7 days; the 200-mg dose was given for 10 days. Samples for pharmacokinetic analyses were obtained on Days 15 and 32; trough plasma concentrations of carbamazepine and its principal metabolite, carbamazepine-10, 11-epoxide (CBZ-E), were determined daily beginning on Day 13. Cognitive function testing was performed on Day 1 before carbamazepine dosing (baseline), Day 15 (carbamazepine alone), and Day 32 (carbamazepine plus sertraline or placebo).

RESULTS

There were no significant differences between the sertraline and placebo groups in any of the pharmacokinetic parameters for carbamazepine or CBZ-E. Carbamazepine alone impaired cognitive function. The addition of sertraline did not potentiate these effects. Side effects were reported by 2 subjects in each group, but none were severe.

CONCLUSION

These findings indicate that sertraline does not affect the pharmacokinetics of carbamazepine or its principal metabolite and does not potentiate the cognitive effects of carbamazepine.

A pilot study of the effect of low level exposure to mercury on the health of dental surgeons

OBJECTIVES

This project was conducted to examine whether the computerised analysis of psychomotor responses available from Cognitive Drug Research is appropriate for measuring an effect of low level exposure to mercury in dentists.

METHODS

A computerised battery of psychomotor tests was given to two groups of dentists (older dentists and trainees) and to two age matched control groups. As well as the psychomotor tests, volunteers were required to complete a questionnaire to identify potential influences on psychomotor performance and to provide a sample for analysis of urinary mercury.

RESULTS

Statistical analysis of the results showed that the older dentists had slightly higher concentrations of urinary mercury although most were around background levels and they were all within occupational limits. Five of the psychomotor tests showed no differences between the performance of the four groups. The older dentists showed significantly better performance on the simple reaction time test and significantly poorer performance in the immediate word recall and delayed word recall tests.

CONCLUSIONS

Poorer performance in memory recall tests confirms previously reported studies. This together with the confirmation that this test system is a practical tool in the occupational setting suggests that a larger study of the effects of mercury exposure on dentists would be appropriate.