Intranasal insulin administration dose-dependently modulates verbal memory and plasma amyloid-beta in memory-impaired older adults

Intranasal insulin administration raises central nervous system (CNS) insulin levels in humans and acutely facilitates verbal memory in patients with Alzheimer's disease (AD), an effect that may differ by APOE genotype. The purpose of this study was to examine the cognitive dose response curves for intranasal insulin administration, and determine whether the effects of insulin differ between participants with (epsilon4+) and without (epsilon4-) the APOE- epsilon4 allele. On separate mornings, 33 memory-impaired adults with AD or amnestic mild cognitive impairment and 59 normal adults each underwent five intranasal treatment conditions consisting of insulin (10, 20, 40, or 60 IU) or placebo. Cognition was tested 15-minutes post-treatment, and blood was acquired at baseline and 45-minutes post-treatment. Plasma insulin and glucose levels were unaffected by treatment. Insulin administration facilitated recall on two measures of verbal memory in memory-impaired epsilon4- adults, with performance generally peaking at 20 IU. In contrast, memory-impaired epsilon4+ subjects demonstrated a relative decline in verbal memory. Insulin also differentially modulated plasma amyloid-beta for memory-impaired subjects and normal controls, effects that again differed by APOE genotype. These findings suggest that groups with different genetic risks for AD may show differential dose-response curves following intranasal insulin administration.

Dextroamphetamine. Its cognitive and behavioral effects in normal and hyperactive boys and normal men

The effects of a single oral dose of dextroamphetamine sulfate on motor activity, vigilance, learning, and mood were compared for normal and hyperactive prepubertal boys and normal college-aged men using a double-blind crossover design. Both groups of boys and men showed decreased motor activity increased vigilance, and improvement on a learning task after taking the stimulant drug. The men reported euphoria, while the boys reported only feeling "tired# or "different# after taking the stimulant. It is not clear whether this difference in effect on mood between adults and children is due to differing experience with drugs, ability to report affect, or a true pharmacologic age-related effect. While there were some quantitative differences in drug effects on motor activity and vigilance between these different groups, stimulants appear to act similarly on normal and hyperactive children and adults.

Neuropsychological function in children with blood lead levels <10 microg/dL

Clear adverse effects of blood lead levels >or=10 microg/dL have been documented in children. Given that the majority of US children have levels below 10 microg/dL, clarification of adverse effects below this cutoff value is needed. Our study evaluated the associations between blood lead levels <10 microg/dL and a broad spectrum of children's cognitive abilities. Data were analyzed from 534 children aged 6-10, enrolled in the New England Children's Amalgam Trial (NECAT) from the urban area of Boston, Massachusetts and rural Farmington, Maine. Adjusting for covariates (age, race, socioeconomic status, and primary caregiver IQ), children with 5-10 microg/dL had 5.0 (S.D. 2.3) points lower IQ scores compared to children with blood lead levels of 1-2 microg/dL (p=0.03). Verbal IQ was more negatively affected than performance IQ, with the most prominent decrement occurring in children's vocabulary. Wechsler Individual Achievement Test scores were strongly negatively associated with blood lead levels of 5-10 microg/dL. In adjusted analyses, children with levels of 5-10 microg/dL scored 7.8 (S.D. 2.4) and 6.9 (S.D. 2.2) points lower on reading and math composite scores, respectively, compared to children with levels of 1-2 microg/dL (p<0.01). Finally, levels of 5-10 microg/dL were associated with decreased attention and working memory. Other than associations of lead exposure with achievement, which even persisted after adjustment for child IQ, the most pronounced deficits were in the areas of spatial attention and executive function. Overall, our analyses support prior research that children's blood levels <10 microg/dL are related to compromised cognition and highlight that these may especially be related to academic achievement.

Does risperidone improve verbal working memory in treatment-resistant schizophrenia?

OBJECTIVE

Treatment efficacy in schizophrenia is typically defined in terms of symptom reduction. However, new antipsychotic medications could potentially have an impact on aspects of disability, such as neurocognitive deficits. The authors evaluated the effects of risperidone on verbal working memory, a memory component of theoretical interest because of its link to prefrontal activity and of practical interest because of its link to psychosocial rehabilitation.

METHOD

Verbal working memory of 59 treatment-resistant schizophrenic patients was assessed as part of a randomized, double-blind comparison of treatment with risperidone and haloperidol. Verbal working memory was measured under both distracting and nondistracting conditions at baseline and after 4 weeks of both fixed- and flexible-dose pharmacotherapy.

RESULTS

Risperidone treatment had a greater beneficial effect on verbal working memory than haloperidol treatment across testing conditions (with and without distraction) and study phases (fixed and flexible dose). The treatment effect remained significant after the effects of benztropine cotreatment, change in psychotic symptoms, and change in negative symptoms were controlled. Neither benztropine status nor symptom changes were significantly related to memory performance.

CONCLUSIONS

Treatment with risperidone appears to exert a more favorable effect on verbal working memory than treatment with a conventional neuroleptic. The beneficial effect appears to be due, at least partially, to a direct effect of the drug, possibly through antagonism of the 5-HT2A receptor. Results from this study suggest that pharmacotherapeutic efficacy in schizophrenia treatment could be broadened to include impact on neurocognitive abilities.

Effects of ketamine on thought disorder, working memory, and semantic memory in healthy volunteers

BACKGROUND

The N-methyl-D-aspartate receptor antagonist, ketamine, produces a clinical syndrome of thought disorder, perceptual distortion, and cognitive impairment.

METHODS

We have administered ketamine to healthy volunteers to characterize the formal thought disorder and specific memory dysfunction associated with ketamine. Ten healthy volunteers underwent a double-blind, placebo-controlled, ketamine infusion (0.12 mg/kg bolus and 0.65 mg/kg/hour). Thought disorder was evaluated with the Scale for the Assessment of Thought, Language and Communication. Cognitive testing involved working and semantic memory tasks.

RESULTS

Ketamine produced a formal thought disorder, as well as impairments in working and semantic memory. The degree of ketamine-induced thought disorder significantly correlated with ketamine-induced decreases in working memory and did not correlate with ketamine-induced impairments in semantic memory.

CONCLUSIONS

This study characterizes the formal thought disorder associated with ketamine and may suggest that ketamine-induced deficits in working memory are associated with ketamine-induced thought disorder.

Cognitive demand and blood glucose

Previous research has identified that glucose administration can enhance cognitive performance, especially during more intense cognitive processing. There appears to be a reciprocal relationship between falling glucose levels and cognitive performance, particularly under conditions of cognitive demand. The present placebo-controlled, double-blind, balanced, crossover study examined the possibility that a high cognitive load may produce changes in blood glucose levels. A secondary aim was to examine the effects of glucose on tasks of varying cognitive demand load. The effects of a glucose drink on participants' performance of a serial subtraction task (computerised Serial Sevens), a somatically matched control task (key-pressing), a short interval Word Memory task and a Word Retrieval (Verbal Fluency) task were assessed. The change in blood glucose during the demanding computerised Serial Sevens was compared to the change occurring during the key-pressing control. Glucose consumption significantly improved performance on Serial Sevens, with a trend for improved performance on Word Retrieval and no effect on the Word Memory task. Compared with the control task, Serial Sevens resulted in a significant reduction in blood glucose in both drink conditions. This accelerated decay was significantly greater following glucose than placebo. It is suggested that the amount of cognitive load associated with task performance is an index of its sensitivity to enhancement by glucose. Furthermore, a period of intense cognitive processing leads to a measurable decrease in levels of peripherally measured blood glucose, which may be linked to increased neural energy expenditure. However, the relative contribution of central and peripheral (e.g. cardiac) activity to this effect has yet to be determined.

Patterns of memory failure after scopolamine treatment: implications for cholinergic hypotheses of dementia

To test the idea that scopolamine provides a suitable pharmacological model of the memory defects associated with cortical or subcortical dementias, we assessed memory on a battery of tasks in healthy young normal subjects who received 0.5 mg scopolamine, 0.1-0.2 mg glycopyrrolate or physiological saline, once each on three separate occasions, and compared the pattern of memory failure induced by scopolamine to that observed on the same tasks in patients with Alzheimer's disease (AD) or Huntington's disease (HD). In agreement with previous reports, scopolamine impaired acquisition and delayed recall of a 14-word list and disrupted retention on the Brown-Peterson distractor task, whereas the peripherally active anticholinergic glycopyrrolate was without effect. However, under scopolamine the pattern of errors made on these memory tasks was quite different from that seen in patients with AD. Scopolamine did not increase the number of false positive errors on delayed recognition of the word list and also failed to increase the number of prior-item intrusions on the Brown-Peterson task. Also, scopolamine did not impair learning of a symbol-digit paired-associate task, and did not reduce the number of words retrieved or increase the number of words repeated on a standardized verbal fluency test. When the effects of scopolamine on memory were compared to the pattern of impairments observed in demented patients with HD, several differences were found. Although scopolamine clearly produces deficits on some measures of anterograde memory, the present findings question whether anticholinergic drugs adequately mimic the full range of memory impairments observed in cortical or subcortical dementias.

Normal intelligence in children with prenatal exposure to carbamazepine

OBJECTIVE

To investigate the effect of antiepileptic drugs, especially carbamazepine and valproate, on intelligence in prenatally exposed children of mothers with epilepsy.

METHODS

Intelligence of 182 children of mothers with epilepsy (study group) and 141 control children was tested in a blinded setting at preschool or school age using Wechsler Preschool and Primary Scale of Intelligence-Revised or Wechsler Intelligence Scale for Children-Revised. Data on maternal antiepileptic treatment and seizures during pregnancy were gathered prospectively. The study group represented approximately 50% of the children born to mothers with epilepsy in Uusimaa province during 1989 through 1994. One hundred seven children were exposed to antiepileptic monotherapy: 86 to carbamazepine and 13 to valproate. Thirty children were exposed to polytherapy: 23 combinations included carbamazepine, and 17 included valproate. The median maternal doses and blood levels during the second half of pregnancy were 600 mg and 26 micro mol/L for carbamazepine and 950 mg and 300 micro mol/L for valproate.

RESULTS

The mean verbal and nonverbal IQ scores in the children exposed in utero to carbamazepine monotherapy were 96 (95% CI, 93-100) and 103 (95% CI, 100-106). They did not differ from control subjects, whose mean verbal and nonverbal IQ scores were 95 (95% CI, 92-97) and 102 (95% CI, CI, 100-105). Significantly reduced verbal IQ scores were found in children exposed to valproate (mean, 82; 95% CI, 78-87) and to polytherapy (mean, 85; 95% CI, 80-90) compared with the other study group children and control subjects.

CONCLUSIONS

Carbamazepine monotherapy with maternal serum levels within the reference range does not impair intelligence in prenatally exposed offspring. Exposures to polytherapy and to valproate during pregnancy were associated with significantly reduced verbal intelligence. The independent effects of valproate remain unconfirmed because the results were confounded by low maternal education and polytherapy.

Profile of executive deficits in cocaine and heroin polysubstance users: common and differential effects on separate executive components

OBJECTIVES

Structure of executive function was examined and we contrasted performance of substance dependent individuals (polysubstance users) and control participants on neuropsychological measures assessing the different executive components obtained. Additionally, we contrasted performance of polysubstance users with preference for cocaine vs heroin and controls to explore possible differential effects of the main substance abused on executive impairment.

METHODS

Two groups of participants were recruited: abstinent polysubstance users and controls. Polysubstance users were further subdivided based on their drug of choice (cocaine vs heroin). We administered to all participants a comprehensive protocol of executive measures, including tests of fluency, working memory, reasoning, inhibitory control, flexibility, and decision making.

RESULTS

Consistent with previous models, the principal component analysis showed that executive functions are organized into four separate components, three of them previously described: updating, inhibition, and shifting; and a fourth component of decision making. Abstinent polysubstance users had clinically significant impairments on measures assessing these four executive components (with effect sizes ranging from 0.5 to 2.2). Cocaine polysubstance users had more severe impairments than heroin users and controls on measures of inhibition (Stroop) and shifting (go/no go and category test). Greater severity of drug use predicted poorer performance on updating measures.

CONCLUSION

Executive functions can be fractionated into four relatively independent components. Chronic drug use is associated with widespread impairment of these four executive components, with cocaine use inducing more severe deficits on inhibition and shifting. These findings show both common and differential effects of two widely used drugs on different executive components.

Effects of nicotine on cognitive deficits in schizophrenia

Several lines of evidence suggest a pathophysiological role for nicotinic receptors in schizophrenia. Activation by nicotine alters physiological dysfunctions, such as eye movement and sensory gating abnormalities, but effects on neuropsychological performance are just beginning to be investigated. Nicotine-induced desensitization and the well-known tachyphylaxis of nicotinic receptors may confound such efforts. In all, 20 schizophrenics, 10 smokers, and 10 nonsmokers were assessed following the administration of nicotine gum and placebo gum. The Repeatable Battery for the Assessment of Neuropsychological Status was administered. Nicotine affected only the Attention Index; there were no effects on learning and memory, language, or visuospatial/constructional abilities. Attentional function was increased in nonsmokers, but decreased in nicotine-abstinent smokers after nicotine administration. The effects of nicotine in schizophrenia do not extend to all areas of cognition. Effects on attention may be severely limited by tachyphylaxis, such that decremented performance occurs in smokers, while modest effects may be achieved in nonsmokers.

Chronic effects of Brahmi (Bacopa monnieri) on human memory

A study is reported on the effects of Brahmi (Bacopa monniera) on human memory. Seventy-six adults aged between 40 and 65 years took part in a double-blind randomized, placebo control study in which various memory functions were tested and levels of anxiety measured. There were three testing sessions: one prior to the trial, one after three months on the trial, and one six weeks after the completion of the trial. The results show a significant effect of the Brahmi on a test for the retention of new information. Follow-up tests showed that the rate of learning was unaffected, suggesting that Brahmi decreases the rate of forgetting of newly acquired information. Tasks assessing attention, verbal and visual short-term memory and the retrieval of pre-experimental knowledge were unaffected. Questionnaire measures of everyday memory function and anxiety levels were also unaffected.

Negative and deficit symptoms in schizophrenia do respond to neuroleptics

Five large-scale placebo-controlled studies are cited to show that, contrary to the contention of Johnstone et al. (1976) and Crow (1980), negative and/or deficit symptoms in schizophrenia do indeed respond to neuroleptic treatment. Further evidence is given that it is the "organic-like" symptoms (visual and olfactory hallucinations, disorientation, and memory deficit) that do not respond to neuroleptics. This would more sensibly reformulate the hypothesis of Johnstone et al. (1976) and Crow (1980) to state that schizophrenic patients with enlarged ventricles tend to show symptoms of organicity and tend not to respond to neuroleptics.

Efficacy and cognitive side effects of tiagabine and topiramate in patients with epilepsy

OBJECTIVE

Whereas the efficacy of the newer antiepileptic drugs (AEDs) is well established, there remain questions regarding their cognitive side effects. Therefore, we performed a comparative open randomized trial with TPM and TGB as add-on therapy, with particular consideration of cognition, mood, and health-related quality of life (HRQOL).

METHODS

Forty-one patients with refractory epilepsy were randomly assigned to one of the two treatment groups (TPM vs TGB) and received neuropsychological testing at baseline (T1), after titration (3 months, T2), and during the maintenance phase (another 3 months, T3). Tests included measures of intelligence, attention, working memory, episodic memory, language, and self-report questionnaires regarding mood and HRQOL. Twenty patients (8 TPM, 12 TGB) discontinued the trial for different reasons (no group difference).

RESULTS

Seizure outcome (intention-to-treat analysis) was comparably good in both groups (8.1% seizure free, 29.7% seizure reduction>50%). From baseline to after the titration paired sample t tests revealed significant deterioration in verbal fluency, language comprehension, working memory, and visual block tapping under TPM and a deterioration in verbal memory (delayed free recall) in the TGB group. These functions remained stable in the maintenance phase. Self-report measures initially indicated concerns about AED side effects in both groups and concerns about worse cognitive functioning and depression under TPM. In the maintenance phase the TGB group reported feeling a lack of energy, whereas patients on TPM demonstrated improvement on all QOLIE scales on a descriptive level.

CONCLUSION

This study demonstrates the comparable efficacy of TPM and TGB. Consistent with previous reports, TPM but not TGB appears to be associated with persistent negative cognitive side effects on frontal lobe-associated functions, the degree of which may be estimated by the fact that this effect was observed with a very small sample size. In contrast, in patients taking TPM, initially negatively affected HRQOL returns to baseline in the long run on a descriptive level. The latter finding may be interpreted in accordance with the observation that objective performance and subjective self-report under TPM can be dissociated.

Neuropsychological evidence of a relatively selective profile of temporal dysfunction in drug-free MDMA ("ecstasy") polydrug users

RATIONALE

Experimental evidence has shown that 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") can act as a serotonergic neurotoxin in laboratory animals. The serotonin system predominantly innervates frontal and limbic regions of the brain and has been associated with consolidatory learning and mnemonic processes in humans.

OBJECTIVES

The aim of the present study was to investigate the cognitive neuropsychological profile of drug-free ecstasy users by employing a selection of tasks previously associated with lesion or neurodegenerative damage to the temporal lobe or fronto-striatal regions.

METHODS

The study comprised 40 participants: 20 ecstasy polydrug users and 20 polydrug users who had never taken ecstasy.

RESULTS

Ecstasy users were significantly impaired on a recognition task for complex visual patterns and spatial working memory, as a function of task difficulty rather than systematic search strategy. They also showed a trend towards impairment on several learning paradigms. Ecstasy users remained relatively unimpaired on most measures associated with prefrontal functioning, with the exception of verbal fluency "letter" generation.

CONCLUSIONS

Initial cognitive deficits in ecstasy polydrug users may be more apparent in tasks known to be sensitive to temporal functioning.

Alcohol, affect, and the disinhibition of verbal behavior

A study was conducted to investigate the effects of acute alcohol administration on affective states and verbal behavior during the ascending and descending limbs of the blood alcohol curve. Sixteen male social drinkers were given alcohol (1.0 g/kg) or placebo in a double-blind crossover research design. Subjects tested while blood alcohol levels (BAL) were ascending close to peak concentration (0.11 g%) described themselves as more elated, friendly, and vigorous than when tested under placebo conditions. As BAL declined, subjects described themselves as more angry, depressed, and fatigued. Cognitive confusion, hostile verbal interaction, and aggressive thematic content were also greater during alcohol intoxication, but these measures were unrelated to direction of change in the BAL curve. It was concluded that (1) the effects of alcohol on affect are biphasic and are closely related to direction of change in the BAL curve, (2) the disinhibition of certain types of verbal behavior is related neither to affective state or to direction of the BAL curve, and (3) the perception of cognitive disorientation may mediate the effects of alcohol on those behaviors normally suppressed by various controlling influences.

A social ecology of hyperactive boys: medication effects in structured classroom environments

Hyperactive boys on methylphenidate (Ritalin), hyperactive boys on placebo, and comparison boys were observed in quasi-naturalistic classroom settings. Ambient stimulation (quiet versus noisy conditions) and source of regulation (self-paced versus other-paced activities) were varied in a 2 x 2 design. Compared to their peers, hyperactive boys on placebo showed lower rates of task attention and higher rates of gross motor movement, regular and negative verbalization, noise-making, physical contact, social initiation, disruption, and acts that were perceived as energetic, inappropriate, or unexpected. Self-paced activities resulted in increased rates of verbalization, social initiation, and high-energy episodes. High ambient noise levels reduced task attention and increased the rates of many other behaviors including verbalization, physical contact, gross motor movement, and high-energy acts. Medication-by-situation interactions emerged for both classroom dimensions, with hyperactive boys on placebo being readily distinguishable from their peers under some classroom conditions and indistinguishable under other conditions. Moderate relationships were found between teacher ratings and many individual behavior categories. Discussion focused on (a) the merits and limitations of a social ecological research perspective, and (b) the implications of these findings for the design of intervention strategies.

Recreational use of 3,4-methylenedioxymethamphetamine (MDMA) or 'ecstasy': evidence for cognitive impairment

BACKGROUND

It has recently been shown that 3,4-methylenedioxymethamphetamine (MDMA) or 'ecstasy' causes long-lasting alterations to brain structure and function in animals, and there is mounting evidence that recreational users of the drug show impairments in some aspects of cognitive functioning including memory for verbal information. The present study investigates possible effects on other cognitive functions and explores the temporal course of development and resolution of these impairments by comparing novice, regular and abstaining users with a matched group of non-users.

METHODS

Eighty participants categorized as non-users, novice users, regular users or currently abstinent users of MDMA were assessed on tests of verbal IQ, reversed digit span, immediate and delayed recall of a prose passage and of a complex geometric figure and verbal fluency.

RESULTS

The four groups were well-matched for verbal IQ and on demographic variables. They differed in frequency of cannabis use over the last month, but this did not correlate with any cognitive test scores. All three groups of MDMA users showed significantly poorer verbal fluency and immediate and delayed prose recall than non-users. Days since last use and total lifetime consumption of MDMA made separate contributions to the variance in recall scores, accounting jointly for almost half of the variance in delayed recall. By contrast, the groups did not differ on either visual recall or reversed digit span.

CONCLUSIONS

The observed deficits provide further evidence of impairments of verbal but not visual memory in MDMA users, and indicate that the deficits are not attributable either to differences in general reasoning ability or to impairment of working memory. The data further suggest that the observed impairments may be attributable to a combination of reversible acute effects of MDMA resolving over a period of 2-3 weeks and more long-term changes associated with extent of lifetime consumption.

Semantic priming in schizophrenia: an examination of spreading activation using word pronunciation and multiple SOAs

Semantic priming in word pronunciation was examined at 5 stimulus onset asynchronies (SOAs) in 75 medicated and 25 unmedicated people with schizophrenia (SCZ) and in 10 depressed and 28 normal controls. At SOAs < 950 ms, SCZ displayed priming similar to that of normal and depressed controls. At the 950-ms SOA, SCZ displayed less priming than controls. Medication dosage, but not conceptual disorganization scores, was positively associated with priming at SOAs < 950 ms. These results suggest that prior reports of enhanced priming in schizophrenia may have been confounded by methodological problems and that automatic priming processes operate normally in SCZ. The failure of SCZ to display significant priming at the 950-ms SOA is consistent with a hypothesized disturbance in higher level processes.

Cognitive and behavioral effects of lamotrigine and topiramate in healthy volunteers

BACKGROUND

The relative cognitive and behavioral effects of lamotrigine (LTG) and topiramate (TPM) are unclear.

METHODS

The authors directly compared the cognitive and behavioral effects of LTG and TPM in 47 healthy adults using a double-blind, randomized crossover design with two 12-week treatment periods. During each treatment condition, subjects were titrated to receive either LTG or TPM at a target dose of 300 mg/day for each. Neuropsychological evaluation included 17 measures yielding 41 variables of cognitive function and subjective behavioral effects. Subjects were tested at the end of each antiepileptic drug (AED) treatment period and during two drug-free conditions (pretreatment baseline and 1 month following final AED withdrawal).

RESULTS

Direct comparison of the two AEDs revealed significantly better performance on 33 (80%) variables for LTG, but none for TPM. Even after adjustment for blood levels, performance was better on 19 (46%) variables for LTG, but none for TPM. Differences spanned both objective cognitive and subjective behavioral measures. Comparison of TPM to the non-drug average revealed significantly better performance for non-drug average on 36 (88%) variables, but none for TPM. Comparison of LTG to non-drug average revealed better performance on 7 (17%) variables for non-drug average and 4 (10%) variables for LTG.

CONCLUSIONS

Lamotrigine produces significantly fewer untoward cognitive and behavioral effects compared to topiramate (TPM) at the dosages, titrations, and timeframes employed in this study. The dosages employed may not have been equivalent in efficacy. Future studies are needed to delineate the cognitive and behavioral effects of TPM at lower dosages.

Elective mutism as a variant of social phobia

To examine the relationship between the syndromes of elective mutism and social phobia, a case of elective mutism associated with social phobia in a 12-year-old girl is presented, and the clinical literature regarding the syndrome of elective mutism is reviewed. Elective mutism or reluctance to speak in unfamiliar social situations may be a symptom of social phobia. Social anxiety is a nearly universal characteristic of children manifesting the syndrome of elective mutism. Elective mutism may respond to treatment with medications that also are effective in the treatment of social phobia. Elective mutism may be a manifestation of social phobia rather than a separate diagnostic syndrome. Pharmacologic treatment may be effective.

Deep brain stimulation of the subthalamic nucleus enhances emotional processing in Parkinson disease

BACKGROUND

High-frequency electrical stimulation of the subthalamic nucleus is a new and highly effective therapy for complications of long-term levodopa therapy and motor symptoms in advanced Parkinson disease (PD). Clinical observations indicate additional influence on emotional behavior.

METHODS

Electrical stimulation of deep brain nuclei with pulse rates above 100 Hz provokes a reversible, lesioning-like effect. Here, the effect of deep brain stimulation of the subthalamic nucleus on emotional, cognitive, and motor performance in patients with PD (n = 12) was examined. The results were compared with the effects of a suprathreshold dose of levodopa intended to transiently restore striatal dopamine deficiency. Patients were tested during medication off/stimulation off (STIM OFF), medication off/stimulation on (STIM ON), and during the best motor state after taking levodopa without deep brain stimulation (MED).

RESULTS

More positive self-reported mood and an enhanced mood induction effect as well as improvement in emotional memory during STIM ON were observed, while during STIM OFF, patients revealed reduced emotional performance. Comparable effects were revealed by STIM ON and MED. Cognitive performance was not affected by the different conditions and treatments.

CONCLUSIONS

Deep brain stimulation of the subthalamic nucleus selectively enhanced affective processing and subjective well-being and seemed to be antidepressive. Levodopa and deep brain stimulation had similar effects on emotion. This finding may provide new clues about the neurobiologic bases of emotion and mood disorders, and it illustrates the important role of the basal ganglia and the dopaminergic system in emotional processing in addition to the well-known motor and cognitive functions.

Characterization of verbal and spatial memory changes from moderate to supraphysiological increases in serum testosterone in healthy older men

BACKGROUND

It has been suggested that cognitive changes in response to T supplementation may occur within an ideal range. The objective of this study was to compare the cognitive responses of older, eugonadal men in whom moderate or large increases in serum testosterone levels was induced by exogenous testosterone supplementation.

DESIGN

Randomized, double-blind, placebo-controlled study with subsequent grouping of participants according to average increase in circulating T from baseline.

SETTING

Community dwelling participants.

PARTICIPANTS

Fifty-seven healthy, eugonadal, community dwelling male volunteers, mean age 67 years (+/-11 years).

INTERVENTIONS

Participants were randomized to receive weekly intramuscular (i.m.) injections of either 50, 100 or 300 mg T enanthate or placebo (saline) injection for 6 weeks. Cognitive evaluations using a battery of neuropsychological tests were conducted at baseline, weeks 3 and 6 of treatment and after 6 weeks of wash-out.

MAIN OUTCOME MEASURES

Performance on cognitive tests of verbal and spatial memory.

RESULTS

Men with moderate increases in serum T and/or its metabolites demonstrated significant improvements in verbal and spatial memory. In contrast, men with large or low increases in circulating T levels, failed to demonstrate significant changes in memory.

CONCLUSION

These results suggest that in healthy older men, beneficial changes in cognitive function induced by T supplementation are most evident with moderate changes in cognition from moderate to high T supplementation increases in T levels. Large or no to low increases in T levels do not appear to appreciably effect cognition.