SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
It has recently become clear that the adult human brain is capable of more plasticity than previously thought. Investigations into the natural history of change following brain injury demonstrate that partial recovery of function can and does occur. Furthermore, there is increasing evidence that intervention through re-training or provision of compensatory memory aids can result in improved cognitive functioning.
Cognition in patients with CAH has not been as well studied as other aspects of psychologic function. Nevertheless, it is possible to make some conclusions and to offer a number of hypotheses for further study (Table 1). First, patients with CAH do not seem to have an overall intellectual advantage as a direct consequence of the disease. The high IQs reported in some groups of patients with CAH are also reported in their siblings and probably reflect sampling bias. Second, it is possible that, on average, patients with salt-wasting CAH have lower overall ability than patients with the simple-virilizing form, but both groups are well within the normal range, and there is considerable variability among both groups. Third, the evidence to date does not confirm that patients with CAH are more likely to have diagnosable learning disabilities when compared with their unaffected relatives, but this issue has not been well studied with the appropriate psychoeducational assessments. It is unlikely that patients with CAH are at substantially increased risk for frank learning disabilities, but they may be likely to have problems in specific areas. Fourth, females with CAH seem to have enhanced spatial ability as a result of exposure to high levels of androgens early in development. The neural substrate of this advantage is unknown but a subject of active research. It is unclear whether when compared with their unaffected siblings, females with CAH are better in other abilities that are typically performed best by males or worse in abilities typically performed best by females. Fifth, it is likely that patients with CAH have other cognitive changes as a consequence of disease characteristics (besides androgens) and of the treatment of the disease. Some evidence suggests that patients with CAH are more likely to have white-matter brain changes produced by the disease and its treatment. This has not been well studied but should be because of the potential clinical implications. It is reasonable to hypothesize that there will be cognitive changes that reflect effects of undertreatment (e.g., ACTH effects on attention) and other changes that reflect effects of overtreatment (e.g., glucocorticoid effects on memory). Some of these effects may be transient, reflecting acute brain changes, whereas others may become chronic as a result of permanent brain changes with repeated exposure. There is need for continuing study of cognition in patients with CAH. Such studies will provide basic information about hormonal effects on cognition and the neural mechanisms that mediate those effects. They will also provide important clinical information to guide psychologic and medical treatment of patients.
This article will review neuroactive steroid effects on serotonin and GABA systems, along with the subsequent effects on cognitive functions. Neurosteroids (such as estrogen, progesterone, and allopregnanolone) are synthesized in the central and peripheral nervous system, in addition to other tissues. They are involved in the regulation of mood and memory, in premenstrual syndrome, and mood changes related to hormone replacement therapy, as well as postnatal and major depression, anxiety disorders, and Alzheimer's disease. Estrogen and progesterone have their respective hormone receptors, whereas allopregnanolone acts via the GABA(A) receptor. The action of estrogen and progesterone can be direct genomic, indirect genomic, or non-genomic, also influencing several neurotransmitter systems, such as the serotonin and GABA systems. Estrogen alone, or in combination with antidepressant drugs affecting the serotonin system, has been related to improved mood and well being. In contrast, progesterone can have negative effects on mood and memory. Estrogen alone, or in combination with progesterone, affects the brain serotonin system differently in different parts of the brain, which can at least partly explain the opposite effects on mood of those hormones. Many of the progesterone effects in the brain are mediated by its metabolite allopregnanolone. Allopregnanolone, by changing GABA(A) receptor expression or sensitivity, is involved in premenstrual mood changes; and it also induces cognitive deficits, such as spatial-learning impairment. We have shown that the 3beta-hydroxypregnane steroid UC1011 can inhibit allopregnanolone-induced learning impairment and chloride uptake potentiation in vitro and in vivo. It would be important to find a substance that antagonizes allopregnanolone-induced adverse effects.
One hundred and ninety-nine elderly stroke patients, who received rehabilitation treatment, were examined, to clarify the relationship between cognitive function and discharge place. The patients who moved to long-term care facilities showed more severe disabilities of basic activities of daily living (ADL), more frequent incontinence, and lower functional impairments (Brunnstrom stage), compared with those discharged to their home. Multivariate regression analysis was done with discharge place as the dependent variable. Independent variables were age, sex, kind of stroke, rehabilitation period, level of ADL and IQ on Kohs test, or performance IQ on the Wechsler Adult Intelligence Scale. Older age, higher levels of ADLs, and higher scores on Kohs test IQ or Wechsler Adult Intelligence Scale Performance IQ were all significantly linked with home discharge. These results suggest that non-verbal cognitive dysfunction may affect discharge place in elderly stroke patients after rehabilitation therapy.
Male Wistar rats were exposed to 75 and 150 ppm of carbon monoxide (CO) from day 1 after birth until postnatal day 10 and their cognitive functions were evaluated at 3 and 18 months of age. The results show that early postnatal exposure to CO does not affect the acquisition and reacquisition of an active avoidance task in both adult and aged rats. Conversely, our previous findings indicate that prenatal exposure to CO (75 and 150 ppm), resulting in maternal blood carboxyhaemoglobin concentrations equivalent to those found in human cigarette smokers, induces long-lasting learning and memory deficits. These findings suggest that neurofunctional sequelae of prenatal CO exposure are notably different from those occurring in response to early postnatal exposure and that the vulnerability of the developing brain to prolonged, relatively mild, decrease in oxygen availability induced by CO critically depends on the particular period of developmental exposure.
This article examines the relationship between hypoglycemia and brain function in children with type 1 diabetes. Hypoglycemic episodes occurring in the first 5 years of life may permanently disrupt cognitive function in a subset of children with diabetes, and a single acute episode of hypoglycemia may produce a transient reduction in mental efficiency, alter the electroencephalogram, and increase regional cerebral blood flow. Because iatrogenic development of hypoglycemic unawareness and autonomic failure are the most likely mediators of moderately severe hypoglycemia, medical management efforts should be directed at the prevention of frequently recurring, mild hypoglycemia.
BACKGROUND: Abuse of methylphenidate, a treatment of attention-deficit/hyperactivity disorder, is reported to be increasing among students for the purpose of improving cognition. METHODS: A single capsule, containing methylphenidate (20 mg) or placebo, was administered to healthy young adults orally following 24 hours of sleep deprivation. Measurements included percent change in score from sleep-deprived baseline on four standardized tests of cognitive function: Hopkins Verbal Learning, Digit Span, Modified Stroop, and Trail Making tests. Measurements also included percent changes in blood pressure and heart rate from sleep-deprived baseline and plasma methylphenidate concentration. RESULTS: Differences in cognitive test performance were not observed between intervention groups. In subjects receiving methylphenidate, mean percent changes from baseline for systolic blood pressure and heart rate were increased relative to placebo between 90 and 210 minutes following capsule administration (maximum increases of 9.45% and 11.03%, respectively). The timing of peak differences in physiologic measures did not correlate with peak serum methylphenidate concentrations. Exit questionnaire ratings of "capsule effect" and perceived performance on the postcapsule administration of the most challenging cognitive test were both higher (p = .044 and p = .009, respectively) for the methylphenidate group than for the placebo group. CONCLUSIONS: Cognitive improvement among sleep-deprived young adults was not observed following methylphenidate administration. Benefits perceived by abusers may relate to increased confidence and sense of well-being, as well as to sympathetic nervous system stimulation. Moreover, methylphenidate administration results in physiologic effects that could be harmful to certain individuals.
OBJECT: A Phase II trial of conformal radiation therapy (CRT) for craniopharyngioma was conducted to determine whether the irradiated volume could be safely reduced to decrease effects on cognitive function. METHODS: Between July 1997 and January 2003, 28 pediatric patients (median age 7.3 +/- 4.12 years) received CRT in whom doses (54-55.8 Gy) were administered to the gross tumor volume (solid and cystic components) surrounded by a 1-cm clinical target volume margin. Patients were evaluated serially with neuropsychometric testing. Statistical analyses were performed to determine the effect of clinical factors and radiation dosimetry on intelligence quotient (IQ). The median follow-up period was 36.6 months (range 24.4-80 months). The estimated 3-year progression-free survival rate was 90.3 +/- 7.3%. Three patients experienced local disease progression. Cognitive outcome for patients was adversely affected by the following factors: age younger than 7.4 years (p = 0.001), an interval between symptoms and diagnosis of more than 73 days (p = 0.06), more extensive surgery (p = 0.014), multiple surgical procedures (p = 0.002), diabetes insipidus (p = 0.02), hydrocephalus at diagnosis (p = 0.009), a cerebrospinal fluid shunt (p = 0.005), shunt revisions (p = 0.01), Ommaya reservoir laterality (p = 0.005), and cyst aspirations (p = 0.02). The percentage of total brain, supratentorial brain, or left temporal lobe volumes receiving a dose in excess of 45 Gy had a significant impact on longitudinal IQ. CONCLUSIONS: The use of CRT with a 1-cm margin for clinical target volume results in tumor control equivalent to that achieved using conventionally planned radiation therapy. Surgical morbidity and a volume-receiving dose more than 45 Gy are factors affecting longitudinal IQ after CRT in patients treated for craniopharyngioma.
Six different studies of social drinkers drawn from California, Oklahoma, Massachusetts and Michigan, using different methodologies, indicate a negative association between social drinking (specifically quantity of alcohol consumed per drinking occasion) and sober cognitive performance. This relationship prevails not only in men but also in women. The decrements in performance are greater in older than in younger individuals, and they are more evident in heavy than in light social drinkers. These findings do not necessarily indicate, albeit they do suggest, a causal link between social drinking and impairments in cognitive functioning. Additional questions raised in this review must be answered before a cause and effect relationship is established between social drinking and cognitive dysfunction.
One patient with frequent spike-waves in EEG was studied by a neuropsychological test. The spike-waves caused an obvious prolongation of cognitive processing. This delay was considered to be caused not only by motor inhibition but also by impaired cognitive function.
A new task for the analysis of drug effects on the cognitive function in mice was investigated using a 4-arm maze with three selectable arms. Each trial consisted of a forced run either to the right or left arm containing a food pellet, which was changed for each trial, followed by a free-choice run after a delay (0-120 sec). The correct response was to turn to the arm 180 degrees opposite from the forced one. Entrance into the center arm in the free-choice run, which was called the non-reward response, was not reinforced at any time. As the delay became longer, correct responses decreased, but non-reward response errors remained unchanged in the well-trained mice. Without increasing the non-reward response, scopolamine and atropine, but not methylscopolamine, decreased the correct response in a delay-dependent manner at a low dose range, while diazepam did so in a delay-independent manner. Physostigmine ameliorated scopolamine-induced impairment in performance, but had less effect on the delay-induced decrease in the correct response. Other tested drugs (chlorpromazine, haloperidol, apomorphine, phentolamine, propranolol, lithium chloride, ketamine, and caffeine) had no significant effect on performance. These results suggest that CNS muscarinic blockades and diazepam treatment selectively attenuate working memory in different ways.
OBJECTIVE: To examine neuropsychologic functions in patients with chronic obstructive pulmonary disease (COPD) and mild hypoxemia compared with patients with mild Alzheimer disease and normal controls. BACKGROUND: Cognitive deficits have been documented in patients with COPD, but few studies have compared the neuropsychologic status of these patients with that of other neurologic groups. METHOD: Cognitive test results from 32 patients with COPD and mild hypoxemia (mean age, 70.3 years; mean education, 13.2 years; mean partial arterial oxygen pressure, 68.8 mm Hg) who had no neurologic symptoms were compared with 31 subjects with mild Alzheimer disease (AD) and 31 normal controls similar in age, education, and sex. Seventy-three percent of the patients with COPD were receiving supplementary oxygen. RESULTS: Significant group differences across 11 cognitive scores were found using analysis of variance, and post hoc analyses indicated that patients with mild AD performed significantly worse than normal controls and patients with COPD on most tests. The group with COPD and the group with AD demonstrated lower letter fluency compared with controls. Although the patients with COPD performed significantly worse than controls on verbal fluency tasks, they were not in the clinically impaired range, and, overall, the group with COPD was similar to the controls on most cognitive tests. CONCLUSIONS: These findings suggest that many patients with COPD and mild hypoxemia who don't have neuropsychiatric histories may perform normally on cognitive measures. Oxygen therapy may partially account for preservation of cognitive function in these patients. Results also suggest that patients with COPD and normal controls can be readily distinguished from patients with mild AD based on levels and patterns of neuropsychologic test results. Any significant cognitive deficits in patients with mildly hypoxemic COPD may warrant continued neurologic evaluation.
As many as 58 children aged 5.6 to 13.6 years with dyspraxia were examined. The tone of musculature, the psychomotor system (postural control, coordination of movements, lateralization of body perception) and cognitive functions were explored. Dissociation of the lateralization of the tone and motor functions together with spatial thinking deficiency were established.
INTRODUCTION: Cerebellum traditionally has been considered as a neural structure dedicated to motor control. Published studies in the last decades suggest that the cerebellum has an important role in behaviour and cognition specially in paediatric age. OBJECTIVE: We review the cerebellum role in cognitive function in developmental and acquired cerebellar pathology.
The objective of this study was to investigate the longitudinal relation between the insulin-like growth factor I (IGF-I)/IGF-binding protein (IGFBP) system and cognitive function. The study population consisted of a sample of 186 healthy participants from the population-based Rotterdam Study, aged 55-80 yr. At baseline, we determined fasting blood levels of free and total IGF-I, IGFBP-1, and IGFBP-3. The 30-point Mini-Mental State Examination (MMSE) was used to assess cognitive impairment at baseline (MMSE score of <26; 6% of the sample) and cognitive decline after, on the average, 1.9 yr of follow-up (drop in MMSE score of >1 point/year; 22% of the sample). Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using logistic regression, with adjustment for age, sex, education, body mass index, and fasting insulin levels. Total IGF-I appeared to be inversely related to cognitive impairment, although not significantly. Higher total IGF-I and the total IGF-I/IGFBP-3 ratio were associated with less cognitive decline (OR per SD increase = 0.65; 95% CI = 0.44-0.95 and OR = 0.59; 95% CI = 0.39-0.87, respectively). No relation was observed between free IGF-I and cognitive decline (OR = 0.99; 95% CI = 0.68-1.44). In conclusion, in this prospective study higher serum total IGF-I levels and higher total IGF-I/IGFBP-3 ratios, but not higher free IGF-I levels, were associated with less cognitive decline over the following 2 yr. Circulating total IGF-I levels may reflect an underlying biological process that influences cognitive decline.
The effects of equi-efficacious doses of the cholesterol-lowering drugs simvastatin (20 mg day-1) and pravastatin (40 mg day-1) on tests of cognitive function were investigated in a double-blind, placebo-controlled, 2-period (4 weeks per period), incomplete block, crossover study of 36 patients (24 per treatment) with hypercholesterolaemia. After 4 weeks neither of the active treatments differed significantly from placebo on any cognitive measure.
BACKGROUND: Military exercises generate high levels of stress to simulate combat, providing a unique opportunity to examine cognitive and physiologic responses of normal humans to acute stress. METHODS: Cognitive and physiologic markers of stress were evaluated before, during, and after an intense training exercise conducted for 53 hours in the heat. Cognitive performance, mood, physical activity, sleep, body composition, hydration, and saliva cortisol, testosterone, and melatonin were assessed. Volunteers were 31 male U.S. Army officers from an elite unit, aged 31.6 +/- .4 years. RESULTS: Wrist activity monitors documented that soldiers slept only 3.0 +/- .3 hours during the exercise and were active throughout. Volunteers lost 4.1 +/- .2 kg (p < .001) of weight, predominately water (3.1 +/- .3 L) (p < .001). Substantial degradation in cognitive function, assessed with computerized tests, occurred. Vigilance, reaction time, attention, memory, and reasoning were impaired (p < .001). Mood, including vigor (p < .001), fatigue (p < .001), confusion (p < .001), depression (p < .001), and tension (p < .002), assessed by questionnaire, deteriorated. The highest cortisol and testosterone levels were observed before the exercise. CONCLUSIONS: This study quantifies the overwhelmingly adverse impact of multiple stressors on cognitive performance, mood, and physiologic parameters, during a continuous but brief military exercise conducted by highly motivated, well-trained officers.
There has been much interest recently in the therapeutic benefits of antioxidants, including a possible protective role in preventing or delaying cognitive decline. This study describes the use of antioxidant supplements among 1,059 rural, noninstitutionalized elderly residents of southwestern Pennsylvania who are participants in the Monongahela Valley Independent Elders Survey. The data were collected during the survey's second wave of follow-up (1989-1991). The mean age of participants was 74.5 years (standard deviation 5.5), and 57.3% were women. Current use of nutritional supplements containing vitamin A, C, or E, beta-carotene, zinc, or selenium was measured through self-report. Subjects were administered a battery of 15 neuropsychological tests measuring performance in several cognitive domains. Of the 1,059 persons, 342 (32.3%) were taking antioxidant supplements. Women and persons with higher levels of education were more often antioxidant users. Antioxidant use did not vary significantly by age, race, or income. In univariate analyses, antioxidant use was significantly and positively associated with performance on several cognitive tests. However, after adjustment for age, education, and sex, there were no significant differences in cognitive test performance between antioxidant users and nonusers. This study is one of only a few that have analyzed the relation between antioxidants and cognition in a community-based sample. After potentially confounding factors are accounted for, the results do not support the hypothesis that antioxidant supplement use is associated with cognitive function.