Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.107 (DAT)
 1,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The EEG alterations attributed to senescence are the complex result of functional as well as organic factors, such as normal physiological aging, pathological process which results in cognitive deterioration, and/or psychological phenomena including depression. The aim of this study is to clarify which factors influence which EEG features and to evaluate the relationship between the clinical and electrophysiological indices. For simplicity, this study focused on the major three factors that are important in dealing with senescence; 1) normal, physiological aging; 2) dementia; 3) depression. A total of 191 subjects participated in this study. The subject groups were classified into 9 groups based on their age and pathology. Two healthy elderly groups (N = 60; between the ages of 60 and 80 years; subclassified according to their social activity), a healthy young volunteers' group (N = 30; between the ages of 20 and 39), a healthy middle-aged volunteers' group (N = 30; between the ages of 40 and 59), four subject groups of dementia of Alzheimer's type [DAT] classified according to the severity of dementia (total number of subjects = 44), depressive elderly subjects (N = 12), and one group of subjects who are older than 80 years (N = 15). The depressive subjects were diagnosed as major depression with their main symptom being psychomotor retardation which resembles the clinical picture of early dementia. The EEGs change with age. This well-approved fact is also confirmed in this study based on ANOVA. Within the same age groups, there were little differences in EEGs regardless of the quality of their social activities. More slow activity, more 20-32Hz fast activity, and less 13.5-20.0Hz beta activity were seen in the socially-inactive group than in the socially-active group (multiple range test based on Tukey's method). The fact that no tendency of increases in slow and fast activities accompanied by a decrease of alpha activity were seen in the socially-active group suggest that having such tendency in their EEG features may be indicative of underlying pathological process that are qualitatively different from normal physiological aging. The moderate grade of those change may not yet cause clinical impairment noticeable as dementia, but appear as less social activity. The EEGs of depressed elderly differed from the socially-inactive elderly as well as the mild dementia particularly in beta frequency bands. There were no significant differences between the socially-inactive elderly and the mild dementia. The tendency of an increase of slow activity and a decrease of alpha activity was seen as the clinical severity of dementia increases. However, these changes reached at the statistically significant level only in the extremely demented subject group. To extract the feature indices of the EEGs, PCA was applied. Five principal components were descriptive of 88% of the data. The EEG features summarized by these components could differentiate the socially-active elderly and the socially-inactive elderly, and the depressed group was distinctively differed from other groups. Interestingly PCA showed the similarity between the socially-inactive elderly and the mild dementia, and the similarity between the middle-aged and the young volunteers. Except for the extreme dementia, subgroups of DAT patients according to the clinical severity did not show distinctive differences in EEG features. The correlation among the EEG derivations was investigated using cluster analysis. The result indicated that the interhemispheric electrophysiological correlation diminishes along with the advancement of the pathological process of the brain. This study indicated that the EEG indices derived from the multivariate analyses are more informative in regard to the relationship among EEG variables as well as these spatial relationship than evaluating the changes in each frequency band alone.
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PMID:[Analytic study on EEG features of aging with/without psychiatric disorders: focussing at the alterations in the EEGs of the healthy, depressive and demented elderlies]. 855 25

With the advancement of technical progress, especially with respect to magnetic resonance imaging, patchy cerebral white matter lesions (WML) are being found with increasing frequency. The (differential) diagnosis between the two main dementias of old age, (senile) dementia of the Alzheimer type ([S]DAT) and vascular dementia (VD) is made more frequently in favour of the latter, since the detection of WML leads to support a vascular origin for dementia. The present article reviews the literature concerning X-ray computed tomography (CT) and magnetic resonance imaging (MRI) in these disorders. For comparison purposes some methodological problems must be taken into account including different scoring systems for WML severity, differences in imaging techniques and in the criteria for the selection of patients and controls. A great number of studies demonstrates a strong association of frequency and severity of WML with increasing age and presence of cerebrovascular risk factors such arterial hypertension. Some studies revealed an association with neuropsychiatric deficits including gait disorders, urinary incontinence, affective lability and reduced attention and information processing speed. In CT studies, about 30% of patients with (S)DAT had WML but 36-88% in MR studies. However, only few studies controlled for the presence of cerebrovascular risk factors. More recent studies - with improved techniques - revealed a higher frequency of (slight or moderate) WML in the (S)DAT group compared to controls. The prevalence of WML in VD patients was 75-97% in CT studies and about 100% in MR studies. Therefore, without the presence of WML, the diagnosis of VD is currently in doubt. A number of in vivo investigations proved consistently - and with different methods - that cerebral blood flow was reduced in WML regions. As shown in some studies the neuropathologic correlates of WML have in common that the relative tissue water content is increased: This includes inflammation, gliosis, complete and incomplete infarctions, dilation of the perivascular (Virchow-Robin) spaces with myelin atrophy. Thus the finding of WML in watershed areas can be understood. Three case reports serve to illustrate the problems pointed out. In conclusion, the occurrence of WML is an unspecific finding which is observed in up to 50% of the elderly. Diagnostic classification as "vascular lesions" or signs of "vascular encephalopathy" or VD based on CT or MRI alone, should not be made.
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PMID:[Patchy changes in white matter in cranial computerized and magnetic resonance tomography--significance for (differential) diagnosis of dementia of the Alzheimer type and vascular dementia]. 857 17

This study was designed to evaluate, whether investigations of cerebral blood flow can be a helpful diagnostic tool in the differential diagnosis between (senile) dementia of Alzheimer's type [(S)DAT] and geriatric depression with cognitive impairment. Under clinical routine conditions we performed Single Photon Emission Computed Tomography (SPECT) using 99mTc-Hexamethylpropyleneamine Oxime (HMPAO) in 23 patients with (S)DAT (14f, 9m; mean age 68.9 y), 17 patients with geriatric depression (9 f, 8 m; mean age 66.4 y) and 12 age-matched controls (9 f, 3 m; mean age 69.2 y). Semiquantitative analysis (corticocerebellar ratios) of eight different regions of interest (ROI) revealed a significantly (p < 0.05) reduced perfusion in the (S)DAT patients compared to the control group. The depression group exhibited perfusion values between the (S)DAT and control group. The difference between the depression and (S)DAT group was most prominent in the left parieto-occipital ROI (p = 0.008). We discuss the data with extensive regard to the literature and conclude that 99mTc-HMPAO SPECT is a valuable additional tool in the differential diagnosis of depression and dementia in the elderly.
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PMID:99mTc-HMPAO-SPECT in the diagnosis of senile dementia of Alzheimer's type--a study under clinical routine conditions. 857 5

The concentrations were determined of triglycerides (TG), total cholesterol (Ch), high density fraction of (HDL-Ch), low density fraction of cholesterol (LDL-Ch), apolipoprotein B (apo-B) in patients with dementia of Alzheimer type (DAT, 14 patients) and multi-infarct dementia (MID, 63 patients). No significant differences in the estimated lipid parameters in both groups were found, except the calculated value of atherogenic index (Ch/HDL-Ch), which was significantly higher in patients with MID. Our results suggest that this parameter is a much more sensitive atherogenic indicator in blood-vessels than other tested lipid parameters. This finding may influence the therapeutic approach to patients with dementia.
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PMID:[Lipid metabolism parameters in patients with multi-infarct dementia and Alzheimer's type dementia]. 875 48

Conversational repair was examined in videotaped samples of spontaneous mealtime talk of 6 normal elderly adults, 5 subjects with early stage dementia of the Alzheimer's type (EDAT) and 5 subjects with middle stage DAT (MDAT) with a family member who acted as a conversational partner. The overall percentage of utterances involved in communication breakdown and repair and the specific proportions of utterances related to conversation problems, signals identifying problems, and repairs, were evaluated. Using the normal dyads as a control group, results showed the differential effects of DAT onset and progression on the conversational repair behavior of both subjects with DAT and their conversational partner. The percentage of conversation involved in repair was significantly higher for MDAT versus control and EDAT dyads. Despite the increase of conversational troubles with DAT onset and progression, the difficulties were repaired successfully the majority of the time. Subjects with EDAT produced more requests for repair than did their conversational partners. However, conversational partners of EDAT subjects used more elaboration repairs than did EDAT subjects. The opposite pattern was observed in the MDAT group where subjects with MDAT created and repaired more conversational problems than did their conversational partner. MDAT subjects produced more discourse trouble sources than did EDAT subjects. It was also observed that MDAT subjects and conversational partners frequently used nonspecific terms to signal misunderstandings. The findings have important implications for developing family caregiver communication enhancement strategies that are specific to the clinical stage of DAT.
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PMID:Conversational repair by individuals with dementia of the Alzheimer's type. 884 67

Stem-completion priming performance in patients with Alzheimer's type dementia (DAT) was explored in three experiments in which both the standard repetition priming effect and a novel indirect form of priming, cohort priming, were measured. In the first experiment, in which study stimuli were words, both priming effects were found to be markedly attenuated in the DAT group. In the second experiment, the study stimuli were specially constructed nonwords, and it was found that cohort priming was present at normal levels in the DAT group. In a third experiment we tested the specific hypothesis that the requirement to overtly articulate target stimuli during the study phase was critical for the appearance of normal cohort priming in the DAT group in Experiment 2, and also for the normal levels of repetition priming which have been reported in some published studies. Two encoding conditions were compared, one in which subjects simply had to read aloud the target words and a second in which subjects were required to make evaluative (pleasantness) ratings for each of the target words (identical to that used in Experiment 1). Stem-completion priming performance following the latter condition was significantly attenuated in the DAT group relative to a healthy control group, but following the "read aloud" encoding condition, normal levels of repetition and cohort priming were observed. It is suggested that the most fruitful approach to understanding the performance of DAT subjects on lexical repetition priming tasks will involve a detailed analysis of language functions and how they interact with other, possibly mnemonic, processes in the generation of primed responses.
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PMID:Stem-completion priming in Alzheimer's disease: the importance of target word articulation. 885 94

Middle-latency somatosensory evoked potentials (MLSEPs) were recorded in four groups of subjects: 13 normal young controls (mean age, 17.9 years). 11 normal elderly (mean age, 66.9 years), 11 patients with dementia of Alzheimer's type (DAT: mean age, 70.5), and four with vascular dementia (mean age, 79.3). MLSEPs in normal elderly showed an increase in the latency of P22, N30, P45, N60, and P100, and in the amplitude of N60. DAT patients also presented such changes; however, the increase in the amplitude of N60 was much more evident than that found in normal aging and was accompanied by a significant increase in amplitude of P45. Patients with vascular dementia tended to show longer latencies and larger amplitudes than the other groups. The increase in amplitude of P45 and N60 in MLSEPs seems to be characteristically associated with normal aging and the development of dementia. It is suggested that the mechanism of such functional changes might be correlated with the structural and neurochemical changes accompanying neuronal loss in these conditions.
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PMID:Scalp topographic mapping of middle-latency somatosensory evoked potentials in normal aging and dementia. 898 47

Recent advances in the clinical and neuroimaging features of vascular dementia (VAD) versus Alzheimer type dementia (DAT) are described. The lacunar type of VAD, which is often accompanied by silent strokes and a progressive course, is easily confused with DAT. Measurements of cerebral blood flow (CBF) and metabolism (CMR) displayed as brain maps, identify VAD from DAT because of the multifocal and often subcortical nature of the infarcts in VAD, which are strikingly different from the diffuse cortical reductions of CBF and CMR in DAT. Thus, neuroimaging is important for establishing the diagnosis in these two most common forms of dementia in the elderly. A dramatic method for separating VAD from DAT is by utilizing the noninvasive acetazolamide test and xenon contrast CT scanning for measuring the cerebral vasomotor capacitance. In DAT the vasodilator reserve is increased due to the law of initial values. In VAD it is absent or severely blunted so that the differences between the two underlying causes of the dementias become readily apparent.
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PMID:Neuroimaging for differentiating vascular from Alzheimer's dementias. 905 79

Clinical electroencephalography is a relatively simple and inexpensive diagnostic tool with a high sensitivity for diffuse organic encephalopathy of various aetiologies but with a rather low specificity for the type of diagnosis. The highest sensitivity is shown in DAT and Parkinson dementia, and in these conditions the degree of EEG abnormality is correlated with the disease severity. Quantification of EEG makes these correlations more reliable and provides a method for monitoring therapeutic effects. Dementias with predominantly frontal pathology show much less EEG abnormality, and in these conditions the EEG is often normal despite obvious clinical dementia. Also, alcohol dementias often show normal EEG patterns. At an early stage of clinical evaluation, EEG may be useful in the discrimination of organic dementia from pseudodementia, because EEG is usually normal in depression, confusion, agitation and other psychiatric conditions. In pseudodementia due to intoxication with sedatives the EEG is usually dominated by diffuse beta activity. At the stage of differential diagnosis of an organic brain disorder, EEG cannot reliably discriminate between encephalopathies secondary to hydrocephalus, AIDS, cerebrovascular disease, B12 deficiency and primary degenerative diseases such as DAT. More specific EEG patterns are seen in acute cerebrovascular lesions, metabolic encephalopathies, i.e. of hepatic origin, Creutzfeldt-Jakob disease, herpes encephalitis, and nonconvulsive status epilepticus as possible causes of a rapidly deteriorating mental and neurological condition. Repeated EEG recordings over time would add significantly to the diagnostic information. New techniques such as topographical brain mapping, analysis of the EEG during REM sleep, coherence analysis of the EEG activity, and the combination of quantified EEG techniques with evoked potentials and event-related potentials will presumably add to the sensitivity as well as the specificity of the electrophysiological methods in the diagnosis of dementia.
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PMID:Electroencephalography as a diagnostic tool in dementia. 906 24

We assessed writing abilities in a cohort of 31 patients with a diagnosis of DAT (in two subgroups, with minimal [MMSE 24-28] and mild [MMSE 16-23] levels of dementia), and 10 matched controls. Central aspects of writing were assessed by both written and oral spelling to dictation of 72 single words varying in frequency (high or low) and predictability of sound-to-spelling correspondences (predictable, unpredictable and irregular). All subjects achieved better scores on high, as compared to low, frequency words. The performance of both patient groups was significantly affected by degree of predictability, and was equivalent in the written and oral spelling conditions. Phonologically acceptable alternative spellings (e.g. 'wade'-->WAID) constituted the majority of errors. More peripheral processes in writing were assessed by copying and cross-case transcription of single letters. Subjects were more successful at copying within case than transcribing across case. Performance was also better--substantially so for the mild DAT group--when the target response in either task was an upper- rather than a lower-case letter. There was considerable heterogeneity in performance on the spelling and the letter tasks. Some patients (even in the more affected DAT group) were unimpaired on both tasks, suggesting that dysgraphia is not a constant feature in early DAT. When writing deficits do become apparent, in the earliest stages of the disease the pattern is most likely to be one of mild surface dysgraphia, a form of central dysgraphia; impairments in more peripheral aspects of writing tend to emerge once the disease has progressed beyond the minimal stage.
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PMID:Dysgraphia in mild dementia of Alzheimer's type. 910 81


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