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PubMed2006

Effects of radiofrequency radiation emitted by cellular telephones on the cognitive functions of humans.

The present study examined the effects of exposure to Electromagnetic Radiation emitted by a standard GSM phone at 890 MHz on human cognitive functions. This study attempted to establish a connection between the exposure of a specific area of the brain and the cognitive functions associated with that area. A total of 36 healthy right-handed male subjects performed four distinct cognitive tasks: spatial item recognition, verbal item recognition, and two spatial compatibility tasks. Tasks were chosen according to the brain side they are assumed to activate. All subjects performed the tasks under three exposure conditions: right side, left side, and sham exposure. The phones were controlled by a base station simulator and operated at their full power. We have recorded the reaction times (RTs) and accuracy of the responses. The experiments consisted of two sections, of 1 h each, with a 5 min break in between. The tasks and the exposure regimes were counterbalanced. The results indicated that the exposure of the left side of the brain slows down the left-hand response time, in the second-later-part of the experiment. This effect was apparent in three of the four tasks, and was highly significant in only one of the tests. The exposure intensity and its duration exceeded the common exposure of cellular phone users.

Adult↗

PubMed2004

Silent cerebral white matter lesions and cognitive function in middle-aged essential hypertensive patients.

BACKGROUND: An association between midlife blood pressure levels and late-life cognitive impairment has been reported. Hypertension is one of the most important factors related to the presence of cerebral white matter lesions, which is a prognostic factor for the development of cognitive impairment. Studies have shown a relationship between white matter lesions and cognitive decline in elderly hypertensive patients. The aim of the present study was to evaluate cognitive function in asymptomatic middle-aged hypertensive patients according to the presence or absence of white matter lesions. METHODS: Sixty never-treated essential hypertensive patients (38 men, 22 women), aged 50 to 60 years (mean age, 54.4 +/- 3.8 years), without clinical evidence of target organ damage, were studied. All patients underwent brain magnetic resonance imaging to establish the presence or absence of white matter lesions, using the Rotterdam criteria. Cognitive function was evaluated by a neuropsychologic test battery measuring attention, memory, intelligence, anxiety, and depression. RESULTS: Twenty-three hypertensive patients (38%) were found to have white matter lesions on brain resonance. These patients exhibited a significantly worse performance on digit span forward, a standardized measure of attention than hypertensives without white matter lesions (4.86 +/- 1.14 v 5.51 +/- 0.97; P =.027). Hypertensive patients with white matter lesions showed no differences on both visual and logical memory tests when compared with patients without lesions. CONCLUSIONS: We conclude that the presence of silent cerebral white matter lesions in middle-aged hypertensive patients is associated with a mild decline in basic attention.

Blood Pressure↗

PubMed2006

Improvement of cognitive functions in chronic schizophrenic patients by recombinant human erythropoietin.

Schizophrenia is increasingly recognized as a neurodevelopmental disease with an additional degenerative component, comprising cognitive decline and loss of cortical gray matter. We hypothesized that a neuroprotective/neurotrophic add-on strategy, recombinant human erythropoietin (rhEPO) in addition to stable antipsychotic medication, may be able to improve cognitive function even in chronic schizophrenic patients. Therefore, we designed a double-blind, placebo-controlled, randomized, multicenter, proof-of-principle (phase II) study. This study had a total duration of 2 years and an individual duration of 12 weeks with an additional safety visit at 16 weeks. Chronic schizophrenic men (N=39) with defined cognitive deficit (>or=1 s.d. below normal in the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS)), stable medication and disease state, were treated for 3 months with a weekly short (15 min) intravenous infusion of 40,000 IU rhEPO (N=20) or placebo (N=19). Main outcome measure was schizophrenia-relevant cognitive function at week 12. The neuropsychological test set (RBANS subtests delayed memory, language-semantic fluency, attention and Wisconsin Card Sorting Test (WCST-64) - perseverative errors) was applied over 2 days at baseline, 2 weeks, 4 weeks and 12 weeks of study participation. Both placebo and rhEPO patients improved in all evaluated categories. Patients receiving rhEPO showed a significant improvement over placebo patients in schizophrenia-related cognitive performance (RBANS subtests, WCST-64), but no effects on psychopathology or social functioning. Also, a significant decline in serum levels of S100B, a glial damage marker, occurred upon rhEPO. The fact that rhEPO is the first compound to exert a selective and lasting beneficial effect on cognition should encourage new treatment strategies for schizophrenia.

Adult↗

PubMed1994

Anatomical evidence for cerebellar and basal ganglia involvement in higher cognitive function.

The possibility that neurons in the basal ganglia and cerebellum innervate areas of the cerebral cortex that are involved in cognitive function has been a controversial subject. Here, retrograde transneuronal transport of herpes simplex virus type 1 (HSV1) was used to identify subcortical neurons that project via the thalamus to area 46 of the primate prefrontal cortex. This cortical area is known to be involved in spatial working memory. Many neurons in restricted regions of the dentate nucleus of the cerebellum and in the internal segment of the globus pallidus were labeled by transneuronal transport of virus from area 46. The location of these neurons was different from those labeled after HSV1 transport from motor areas of the cerebral cortex. These observations define an anatomical substrate for the involvement of basal ganglia and cerebellar output in higher cognitive function.

Animals↗

PubMed1993

Influence of counterregulatory hormones, independently of hypoglycaemia, on cognitive function, warning symptoms and glucose kinetics.

1. To assess the influence of counterregulatory hormones, independently of neuroglycopaenia, on higher cerebral (cognitive) function, 'hypoglycaemic' warning symptoms and glucose kinetics, 10 healthy subjects participated in two hyperinsulinaemic (2 m-units min-1 kg-1) glucose clamp studies. After 100 min of euglycaemia (plasma glucose level 5 mmol/l), the plasma glucose level was either (a) maintained at 5 mmol/l for 120 min by glucose infusion with concomitant replacement of counterregulatory hormones (continuous infusions of glucagon, adrenaline, noradrenaline, cortisol and growth hormone) to mimic the hormonal milieu normally associated with hypoglycaemia (hormone infusion study) or (b) lowered to 2.8 mmol/l for 120 min (hypoglycaemia study). Assessments were made of cognitive function (P300 auditory evoked responses), symptoms (visual analogue scales) and glucose kinetics (3-[3H]glucose). 2. Hypoglycaemia was associated with an increase in all symptoms (facial flushing, palpitations, tingling, trembling, sweating, hunger, light-headedness and sleepiness, P < 0.01) and all subjects were aware that blood glucose levels had fallen. P300 evoked potential latency increased from 280 +/- 6 to 312 +/- 5 ms (mean +/- SEM, P < 0.01). In contrast, P300 latency and several individual symptoms (hunger, facial flushing, sweating and light-headedness) did not change from baseline during the hormone infusion study (P < 0.05 versus hypoglycaemia). Hepatic glucose production was lower (1.5 +/- 0.4 versus 2.3 +/- 0.3 mg min-1 kg-1, P < 0.05) and peripheral glucose uptake was higher (7.4 +/- 1.0 versus 5.6 +/- 0.6 mg min-1 kg-1, P < 0.01) during infusion of the hormones compared with during hypoglycaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2005

Pre-existing hypertension and the impact of stroke on cognitive function.

Hypertension has been associated with subclinical injury in the brain and may therefore increase the impact of an incident stroke on cognitive function. The Study of Osteoporotic Fractures (SOF) is a prospective, observational study of 9,704 women aged 65 years and older recruited from four U.S. metropolitan areas. Blood pressure was measured at study entry, and cognitive decline was defined by the change from prestroke to poststroke cognitive testing. During an average follow-up of 6.8 years, incident stroke occurred in 260 participants (3.1%) who had previously completed baseline cognitive testing. Among participants with stroke, 119 completed follow-up cognitive testing a median of 1.9 years after the stroke, 80 died before the next study visit, and 61 did not complete further cognitive testing. After adjustment for demographic factors and other confounders, pre-existing hypertension was a strong predictor of cognitive decline when a stroke occurred (odds ratio [OR], 4.07; 95% confidence interval [CI], 1.37-12.1). In contrast, hypertension was only weakly associated with cognitive decline in the absence of stroke (OR, 1.13; 95% CI, 1.04-1.22) (p for interaction = 0.032). Pre-existing hypertension in women is associated with a greater impact of stroke on cognitive function, possibly by influencing the ability to tolerate or recover from brain injury.

Aged↗

PubMed1987

Effect of lithium carbonate on lateralized cognitive functions.

The effect of lithium carbonate on lateralized cognitive functions was studied by asking a patient suffering from a manic-depressive disorder to repeatedly recognize a given series of digits delivered dichotically while varying the dosage of lithium carbonate intake. The data showed that, whereas digit recognition from the right ear (left hemisphere) was about the same across tests, recognition from the left ear (right hemisphere) varied systematically with dosage variations. Specifically, it was found that an increase in dosage of lithium carbonate was associated with a decrease in recognition from the left ear. These data might indicate unilateral hemispheric effects of lithium carbonate on the dysfunctional right hemisphere of patients suffering from bipolar affective disorders. Clinical implications of the findings of the present case study are also discussed.

Adult↗

PubMed1991

Regional cerebral blood flow and cognitive function in patients with chronic liver disease.

Subtle impairments of cognitive function may be an important cause of occupational and psychosocial morbidity in patients with chronic liver disease. Correlation of structural brain abnormalities with cognitive deficits has yielded inconsistent results. 10 patients with cirrhotic liver disease were compared with 10 age, education, and intelligence matched control subjects. Neuropsychological assessment revealed significant overall cognitive impairments in cirrhotic patients compared with controls (p = 0.02). Regional cerebral blood flow was measured by single photon emission computed tomography (SPET or SPECT) and showed increased uptake of radiotracer in the right and left posterior parts of the basal ganglia and right occipital lobe, together with reduced uptake in the right anterior cingulate region. The degree of cognitive impairment was directly correlated with functional abnormalities in the basal ganglia and limbic cortex (p less than 0.05). Our results suggest that impaired cognitive status may be associated with abnormalities of regional brain function in patients with chronic liver disease. Since these deficits are clinically inapparent, our findings have important implications for identification and management of patients with chronic liver disease.

Analysis of Variance↗

PubMed2000

Effects of lovastatin on cognitive function and psychological well-being.

PURPOSE: Animal research and cross-sectional studies suggest that serum lipid concentrations may influence cognitive function, mood, and behavior, but few clinical trials have studied these effects. SUBJECTS AND METHODS: In this double-blind investigation, 209 generally healthy adults with a serum low-density-lipoprotein (LDL) cholesterol level of 160 mg/dL or higher were randomly assigned to 6-month treatment with lovastatin (20 mg) or placebo. Assessments of neuropsychological performance, depression, hostility, and quality of life were conducted at baseline and at the end of the treatment period. Summary effect sizes were estimated as z scores on a standard deviation (SD) scale. RESULTS: Placebo-treated subjects improved between baseline and posttreatment periods on neuropsychological tests in all five performance domains, consistent with the effects of practice on test performance (all P <0.04), whereas those treated with lovastatin improved only on tests of memory recall (P = 0.03). Comparisons of the changes in performance between placebo- and lovastatin-treated subjects revealed small, but statistically significant, differences for tests of attention (z score = 0.18; 95% confidence interval (CI), 0.06 to 0.31; P = 0.005) and psychomotor speed (z score = 0.17; 95% CI, 0.05 to 0.28; P = 0. 004) that were consistent with greater improvement in the placebo group. Psychological well-being, as measured several ways, was not affected by lovastatin. CONCLUSION: Treatment of hypercholesterolemia with lovastatin did not cause psychological distress or substantially alter cognitive function. Treatment did result in small performance decrements on neuropsychological tests of attention and psychomotor speed, the clinical importance of which is uncertain.

Adult↗

PubMed1987

Social drinking and cognitive functioning in college students: a replication and reversibility study.

The purposes of this study were to replicate a previous study of the relationship between alcohol consumption and cognitive functioning in college students and to investigate the reversibility of negative effects of social drinking on cognitive functioning when randomly assigned subjects abstained from drinking for 2 weeks. The previous study was replicated by administering the same battery of neuropsychological tests to 170 subjects (103 women) during the first testing session. Like the original study, the present study demonstrated several significant predicted inverse relationships between drinking and cognitive performance, but specific relationships between various drinking and cognitive variables were not replicated. As in the original study, some significant nonpredicted relationships also occurred. At the end of the first testing session, subjects were randomly assigned either to abstain from drinking or to maintain their usual drinking patterns for 2 weeks. They were then administered a different neuropsychological battery designed to assess functions similar to the original battery. Consumption the previous 2 weeks was significantly lower in the abstain group than in the maintain group, but there were no significant differences in the predicted direction between groups on the cognitive variables. Several significant predicted inverse correlations between drinking variables and cognitive performance occurred, but some nonpredicted relationships occurred also. Problems and implications for research in social drinking are discussed.

Adult↗

PubMed2004

Determining the effects of antiepileptic drugs on cognitive function in pediatric patients with epilepsy.

The majority of children with epilepsy are of normal intelligence; however, a significant subset suffers from temporary or permanent cognitive impairment. Factors that affect cognitive function are myriad and include the neuropathology underlying the epilepsy, seizures, epileptiform activity, psychosocial problems, and antiepileptic drug side effects. Although cognitive impairment is often wrongly attributed to the effects of antiepileptic drugs, antiepileptic drugs do impair cognition in some children. Clinicians should be aware of the differential cognitive effects of antiepileptic drugs and should monitor cognitive function closely when adding or changing therapy. Based on published data from prospective, chronic dosing studies, phenobarbital and topiramate have the highest potential for causing cognitive dysfunction.

Anticonvulsants↗

PubMed2003

Estrogen and cognitive functioning in women.

Research in basic neuroscience has provided biological plausibility for the hypothesis that estrogen replacement therapy (ERT) would protect against cognitive aging in healthy women. The weight of the evidence from randomized controlled trials of estrogen and cognition in women shows that this hormone preferentially protects verbal memory in postmenopausal women, whereas findings from observational studies are less consistent and show a more diffuse effect of estrogen on a range of cognitive functions. There is fairly consistent evidence from epidemiological studies that ERT significantly reduces the risk of Alzheimer's disease (AD) in women. On the other hand, findings from controlled treatment trials of women diagnosed with probable AD failed to show that physiological doses of ERT ameliorate existing deficits in cognitive functioning and/or prevent further deterioration in memory that inevitably occurs in these women over time. Finally, an accumulating body of evidence is beginning to suggest that the immediate postmenopausal period may constitute a critical window for treatment with ERT that maximizes its potential to protect against cognitive decline with aging and/or to reduce the risk of AD.

Adult↗

PubMed2005

Studies of the effects of high fat diets on cognitive function in a rat model.

This research summarises a research program that is concerned with the effects of high fat diets on cognitive function in rats. The diets selected accurately represent current upper limits of human fat consumption in western societies. Rats fed with diets high in saturated or unsaturated fat for 3 months, were severely impaired on a range of learning and memory tasks. Related studies showed that these effects were modulated by concentration of fat, environmental influences, and treatment with glucose. More work is needed to identify the neurobiological mechanisms underlying this impairment but saturated fatty acid intake, as well as insulin resistance and glucose intolerance may be important factors. In demonstrating a clear relationship between obesity and cognitive impairment, this research has important implications for aging. Older adults are particularly vulnerable to the adverse effects of dietary fat and the present results underscore the importance of evidence that seniors with marginal levels of nutrient intake often perform poorly on tests of cognitive function, and are at increased risk for various forms of dementia.

Animals↗

PubMed1984

Decreased cognitive function in aging non-insulin-dependent diabetic patients.

A cross-sectional study was conducted to determine whether normal, age-related declines in cognitive function are accelerated in non-insulin-dependent (type II) diabetes mellitus. Study participants ranged in age from 55 to 74 years. Results indicate that cognitive function is inferior in the patients with type II diabetes compared with a comparably aged, nondiabetic control group. On the basis of a series of cognitive tests, it appears that the cognitive impairment is due to a deficiency in memory retrieval rather than to an attentional or encoding deficit. Cognitive performance is poorer in diabetic patients with peripheral neuropathy or elevated hemoglobin A1c levels. The apparent cognitive impairment in aging patients with type II diabetes may complicate adherence to medical regimens.

Aged↗

PubMed2005

Independent effects of tobacco abstinence and bupropion on cognitive function in schizophrenia.

OBJECTIVE: The objective of this study was to examine the effects of tobacco abstinence and bupropion treatment on cognitive functioning in adult smokers with schizophrenia in the setting of a randomized, double-blind, placebo-controlled clinical trial of bupropion for smoking cessation. METHOD: Fifty-three adults with schizophrenia (DSM-IV) took part in a trial of bupropion for smoking cessation. Subjects were enrolled in the study from August 1999 to March 2003. Forty-five subjects remained in the trial at week 4; 41 subjects, 19 taking bupropion and 22 taking placebo, completed the baseline and week 4 cognitive assessments and were included in the analysis of adjusted effects of abstinence and bupropion treatment on cognitive function. RESULTS: Controlling for bupropion treatment and baseline performance, 7 days of tobacco abstinence was associated with slowed motor speed (finger tapping) but was not associated with worsening of performance on tests of attention (AX Continuous Performance Test [AX-CPT]), verbal learning and memory (California Verbal Learning Test [CVLT]), working memory (digit span), or executive function/inhibition (Stroop) and was not associated with worsening of any clinical measures. Controlling for abstinence status, bupropion was associated with reduction (improvement) in reaction time variability on the AX-CPT and with reduction in perseverative errors on the CVLT. CONCLUSION: We conclude that 1 week of tobacco abstinence is associated with slowed motor speed but is not associated with detectable worsening in performance on a range of neuropsychological tests or clinical symptoms in the subset of patients who were able to quit smoking. We also conclude that bupropion treatment may be associated with improvement in variability of attention.

Adult↗

PubMed2004

Managing and analysing data from a large-scale study on Framingham Offspring relating brain structure to cognitive function.

At the Framingham Heart Study under separate research grant funding from the National Institute of Aging, NIH, we are gathering brain structure and cognitive information on the Framingham Offspring, creating one of the largest known data sets to assess changes in brain structure associated with normative ageing and cognitive decline. Subject recruitment, data collection, data management and statistical analysis require a collaborative integrated effort on the part of the Framingham project team. Here we describe this effort, as well as the various brain structure and cognitive function parameters we are now collecting. We are currently performing analyses of data collected through 2002, and we discuss the statistical issues arising relating brain structure parameters to cognitive function.

Aged↗

PubMed2001

Neurophysiological evaluation of late effects of adjuvant high-dose chemotherapy on cognitive function.

OBJECTIVES: To evaluate late neurotoxicity of adjuvant high-dose (HD) chemotherapy versus standard-dose (SD) chemotherapy by event-related potentials (ERP) and quantitative electroencephalography (qEEG). PATIENTS AND METHODS: From a randomized study in high-risk breast cancer patients on the efficacy of high-dose versus standard-dose adjuvant chemotherapy, late effects on cognitive functioning were analyzed by neuropsychological tests. Cognitive impairment was found in 32% of the HD group, 17% of the SD group and in 9% of a control group of stage I breast cancer patients not treated with chemotherapy. In 17 consecutive patients in the HD group and 16 consecutive patients in the SD group neurophysiological tests were performed, consisting of P300 and qEEG. Results of patients treated with chemotherapy were compared with results of 14 control patients not treated with chemotherapy. All patients were tested two years after treatment. RESULTS: Asymmetry of the alpha rhythm of > or =0.5 Hz was found in 7 HD patients, 2 SD patients and in none of the control patients (p = 0.01). No differences were found between the groups with regard to frequency of alpha rhythm, alpha blocking and latency of P300. No correlation was found between neurophysiological parameters and neuropsychological performance, except for an overall relation between the P300 latencies and the total number of deviant test scores. CONCLUSION: Although the neurophysiological differences are subtle and the relation with the cognitive functioning in individual patients as measured by the neuropsychological examination is equivocal, the results suggest that there is neurophysiological support for cognitive dysfunction as a late complication of high-dose systemic chemotherapy in breast cancer.

Alpha Rhythm↗

PubMed2004

Cognitive functioning and length of abstinence in polysubstance dependent men.

To date, there are few large-scale studies that have examined the relationship between duration of abstinence and cognitive functioning in polysubstance-dependent individuals. Existing large-scale studies of polysubstance abusers have reported only minimal recovery of cognitive functioning with abstinence [Arch. Gen. Psychiatry 35 (1978) 1063]. The goal of this study is to test whether length of abstinence (1 day and 14 months) is related to cognitive ability in a large cross-sectional sample of men recovering from dependence on at least two drugs (N = 207). A series of Poisson and linear regressions were run to test whether length of abstinence is associated with neuropsychological performance while controlling for demographic variables, raw Vocabulary score, drug use, and dependency. The primary finding is that increasing length of abstinence was not statistically associated with superior neuropsychological ability. This suggests that the abuse of multiple substances potentially produces long-lasting neuropsychological impairment with minimal recovery of functioning over a 1-year period.

Adult↗