Genetic variants of dopamine receptor D4 and psychopathology.
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There is much evidence to indicate that the dopamine receptor D4 (DRD4) gene is involved in psychiatric disorders. We investigated the correlation between DRD4 gene polymorphism and the psychopathology of major psychoses, independently of diagnoses. Some 461 inpatients affected by major psychoses were assessed by the Operational Criteria checklist for psychotic illness and typed for DRD4 variants. The four symptomatologic factors-mania, depression, delusion, and disorganization-were used as phenotype definitions. DRD4 Exon 3 long allele variants were associated with high delusional scores, with the most significant difference between alleles 2 and 7 (p = 0.004). DRD4 variants may, therefore, constitute a liability factor for development of delusional symptomatology in patients with major psychoses. (+info)
Effects of repeated hypoglycemia on cognitive function: a psychometrically validated reanalysis of the Diabetes Control and Complications Trial data.
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OBJECTIVE: To test the conclusion that there is no association between multiple episodes of severe hypoglycemia and cognitive decrements by reanalyzing the data from the Diabetes Control and Complications Trial (DCCT) with psychometrically validated cognitive factors and to conduct a novel analysis of the association between individual differences in baseline cognitive ability and episodes of severe hypoglycemia documented after baseline. RESEARCH DESIGN AND METHODS: The factor structure of cognitive ability in the neuropsychological data from the DCCT study was derived. Four cognitive factors (spatial ability, processing speed, memory, and verbal ability) were extracted. Changes in patients' cognitive scores for each year of follow-up were obtained, and paired comparisons of these change scores were performed between groups experiencing zero and five or more hypoglycemic episodes. The association between cognitive ability at baseline and number of subsequent episodes of severe hypoglycemia was also examined. RESULTS: Repeated episodes of hypoglycemia were found not to be associated with cognitive decline in any of the validated cognitive factors. No significant association was found between prospectively documented numbers of severe hypoglycemic episodes and baseline cognitive ability level. CONCLUSIONS: Repeated episodes of hypoglycemia were not related to cognitive decrement, and initial mental ability level was not associated with eventual numbers of hypoglycemic episodes in this group of patients. (+info)
Hippocampal remodeling and damage by corticosteroids: implications for mood disorders.
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Mood disorders are common, recurrent and disabling illnesses which are frequently associated with hypothalamic-pituitary-adrenal (HPA) axis dysregulation and memory loss. The hippocampus provides negative feedback to the HPA axis and has an important role in key aspects of spatial and declarative memory. Thus, hippocampal dysfunction could account for both the memory impairment and neuroendocrine abnormalities found in mood disorders. The critical role of the hippocampus in declarative memory, emotional processing, and vulnerability to stress has been demonstrated in both animal and human studies. Cellular processes in the hippocampus including long-term potentiation, neurogenesis, and dendritic remodeling are currently areas of intense study. Human studies report cognitive impairment consistent with hippocampal dysfunction in depression, bipolar disorder, Cushing's disease, and in those individuals receiving exogenous corticosteroids. This review examines data on the role of corticosteroids in hippocampal remodeling and atrophy in patients with mood disorders. Interventions to prevent or reverse the damaging effects of corticosteroids on the hippocampus are discussed. (+info)
A neurological disease caused by an expanded CAG trinucleotide repeat in the TATA-binding protein gene: a new polyglutamine disease?
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To investigate whether the expansion of CAG repeats of the TATA-binding protein (TBP) gene is involved in the pathogenesis of neurodegenerative diseases, we have screened 118 patients with various forms of neurological disease and identified a sporadic-onset patient with unique neurologic symptoms consisting of ataxia and intellectual deterioration associated with de novo expansion of the CAG repeat of the TBP gene. The mutant TBP with an expanded polyglutamine stretch (63 glutamines) was demonstrated to be expressed in lymphoblastoid cell lines at a level comparable with that of wild-type TBP. The CAG repeat of the TBP gene consists of impure CAG repeat and the de novo expansion involves partial duplication of the CAG repeat. The present study provides new insights into sporadic-onset trinucleotide repeat diseases that involve de novo CAG repeat expansion. (+info)
Thermolabile methylenetetrahydrofolate reductase gene and the risk of cognitive impairment in those over 85.
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OBJECTIVES: Previous reports have shown raised plasma concentrations of homocysteine in older persons with cognitive impairment. This may be caused by environmental and genetic factors. The relation between cognitive function and a common ala/val mutation in the methylenetetrahydrofolate reductase (MTHFR) gene was studied in those over 85. Homozygous carriers of this mutation are characterised by a lifelong exposure to moderately raised plasma concentrations of homocysteine. METHODS: In the Leiden 85-plus Study, a population based study of persons aged 85 years and over, the score on the mini mental state examination (MMSE) and the presence of dementia dependent on the MTHFR genotypes were compared in 641 participants (456 women, 185 men) at baseline. In addition, the association between the MTHFR genotype and cognitive decline was studied by re-examining cognitive function of 172 participants without dementia at baseline after a median follow up of 4.0 years. RESULTS: At baseline, carriers of the ala/ala genotype had a median MMSE score of 27 points (interquartile range (IQR) 21.5-29), for the ala/val genotype it was 26 points (IQR 20-29), and for the val/val genotype it was 27 points (IQR 20-28.3) (p=0.3). The prevalence of dementia was also not significantly different for the various genotypes (ala/ala 22%, ala/val 28%, val/val 27%; p=0.4). None of the carriers of the val/val genotype without cognitive impairment at baseline developed dementia during the follow up. CONCLUSIONS: Although previous studies have shown that older persons with cognitive impairment have raised plasma concentrations of homocysteine, homozygosity for the ala to val mutation in the MTHFR gene is not a genetic risk factor for cognitive impairment in persons aged 85 years and over. (+info)
Inducible nitric oxide synthase is an endogenous neuroprotectant after traumatic brain injury in rats and mice.
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Nitric oxide (NO) derived from the inducible isoform of NO synthase (iNOS) is an inflammatory product implicated both in secondary damage and in recovery from brain injury. To address the role of iNOS in experimental traumatic brain injury (TBI), we used 2 paradigms in 2 species. In a model of controlled cortical impact (CCI) with secondary hypoxemia, rats were treated with vehicle or with 1 of 2 iNOS inhibitors (aminoguanidine and L-N-iminoethyl-lysine), administered by Alzet pump for 5 days and 1. 5 days after injury, respectively. In a model of CCI, knockout mice lacking the iNOS gene (iNOS(-/-)) were compared with wild-type (iNOS(+/+)) mice. Functional outcome (motor and cognitive) during the first 20 days after injury, and histopathology at 21 days, were assessed in both studies. Treatment of rats with either of the iNOS inhibitors after TBI significantly exacerbated deficits in cognitive performance, as assessed by Morris water maze (MWM) and increased neuron loss in vulnerable regions (CA3 and CA1) of hippocampus. Uninjured iNOS(+/+) and iNOS(-/-) mice performed equally well in both motor and cognitive tasks. However, after TBI, iNOS(-/-) mice showed markedly worse performance in the MWM task than iNOS(+/+) mice. A beneficial role for iNOS in TBI is supported. (+info)
Cognitive function and mood after profound nocturnal hypoglycaemia in prepubertal children with conventional insulin treatment for diabetes.
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OBJECTIVES: To examine the frequency of nocturnal hypoglycaemia, and the effects on cognitive function and mood, in children with insulin dependent diabetes mellitus (IDDM). DESIGN: Two overnight glucose profiles, in the home environment, and assessments of cognitive function and mood the following day. Twenty nine prepubertal patients with IDDM (median age, 9.4 years; range, 5.3-12.9) and 15 healthy controls (single overnight profile), median age 9.5 (range, 5.6-12.1) years were studied. RESULTS: Asymptomatic hypoglycaemia (glucose < 3.5 mmol/l) was observed in 13 of 29 patients studied on night 1: four of these and seven others were hypoglycaemic on night 2. The median glucose nadir was 1.9 (range, 1.1-3.3) mmol/l and the median duration of hypoglycaemia was 270 (range, 30-630) minutes. Hypoglycaemia was related to insulin dose, but not glycosylated haemoglobin (HbA1c) values, and was partially predicted by a midnight glucose of < 7.2 mmol/l. Cognitive performance was not altered after hypoglycaemia but a lowering of mood was observed. CONCLUSIONS: Young children on conventional insulin regimens are at high risk for profound, asymptomatic nocturnal hypoglycaemia, which is difficult to predict. There was no short term effect on cognitive function but mood change was detected. (+info)
DHEA deficiency syndrome: a new term for old age?
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Dehydroepiandrosterone (DHEA) is a steroid secreted by the adrenal cortex, with a characteristic, age-related, pattern of secretion. The decline of DHEA concentrations with age has led to the suggestion that old age represents a DHEA deficiency syndrome and that the effects of ageing can be counteracted by DHEA 'replacement therapy'. DHEA is increasingly being used in the USA, outside medical supervision, for its supposed anti-ageing effects. This commentary weighs the evidence for the existence of a DHEA deficiency syndrome and considers the value of DHEA 'replacement therapy'. (+info)