Diagnosis Of Dementia Of The Alzheimer Type Research Articles

Amyloid beta protein precursors with kunitz-type inhibitor domains and acetylcholinesterase in cerebrospinal fluid from patients with dementia of the Alzheimer type.

We used the ELISA to measure the concentration of amyloid protein precursor with Kunitz type trypsin inhibitor domains (APPI) in CSF of dementia of the Alzheimer type (DAT) and examined the correlation of APPI with acetylcholinesterase (AChE) and somatostatin (SRIF). We found the APPI concentration in CSF of DAT to be significantly elevated compared with that of multi-infarct dementia and controls. We could significantly correlate APPI with AChE, but not correlate APPI with SRIF. The present results suggest that measurement of CSF APPI levels may be useful for diagnosis of DAT and the change of APPI may closely be associated with abnormality of acetylcholine system in DAT that has been reported.

Accelerated Weight Loss May Precede Diagnosis in Alzheimer Disease

To determine the association of weight loss and the onset of dementia of the Alzheimer type (DAT) and to characterize the rate of weight change over time in older adults (aged 65-95 years) who develop DAT vs those who remain without dementia. Rates of weight change were investigated in older adult research participants (N = 449) who were enrolled as control subjects without dementia and followed up longitudinally (6 years on average) at the Alzheimer's Disease Research Center, Washington University School of Medicine. Some individuals (n = 125) eventually developed DAT; the others (n = 324) remained without dementia. Body weight was measured at each annual assessment. Piecewise linear regression and random effects models were used to test longitudinal rates of weight change between the groups. Participants without dementia lost about 0.6 lb per year. For those individuals who developed DAT, about 1 year before the detection of DAT, the rate of weight loss doubled (1.2 lb per year). As a group, participants who eventually developed DAT weighed less (about 8 pounds) at study enrollment (ie, when they did not have dementia) than participants who remained without dementia. Aging with and without DAT is associated with weight loss; however, weight loss may accelerate before the diagnosis of DAT. Specific factors contributing to weight loss are unknown, but these data suggest they operate before the development of DAT. Hence, weight loss may be a preclinical indicator of Alzheimer disease.

Telemedicine, dementia and Down syndrome: Implications for Alzheimer disease

Background Individuals with Down syndrome (DS) who are at risk for dementia of the Alzheimer type (DAT) often live at sites remote from major medical centers. Telemedicine (TM) is a modality for providing medical care at remote locations but is underutilized for populations with Alzheimer disease (AD). Methods We studied the feasibility of using TM to evaluate symptoms of DAT in 90 individuals with DS. Dementia was assessed by an informant questionnaire, a direct measure of praxis, pathological reflexes on the neurologic examination, and the presence of cortical atrophy on a neuroimaging procedure. The neurologist was blinded to the scores on neuropsychological measures. Differences in average cognitive scores between a TM and traditional academic medical center–based clinic site (TAC) were tested using 2-way analysis variance with site and premorbid IQ as factors. Logistic regression was used to explore the relationship, in addition to the cognitive scores, of influences such as age, premorbid IQ, and site to the prediction of the physician’s diagnosis of dementia. Results Components of the neurologic, imaging, and neuropsychological examinations differentiated subjects with and without DAT ( p≤0.008) irrespective of whether a subject was evaluated at a TM or TAC site. Conclusions It is feasible to make a diagnosis of DAT in DS by TM. This study supports the need for formal reliability and validity studies of TM preparatory to the consideration of this modality for use in clinical trials for AD.

Cued recall in early-stage dementia in adults with Down's syndrome.

Memory declines were evaluated with an adaptation of the Cued Recall Test (CRT) in 19 adults with Down's syndrome (DS) with mild or moderate intellectual disability (ID) who were at an early-stage of dementia of the Alzheimer type (DAT), and their performance was compared to peer groups of 75 adults with DS and 66 adults with ID without DS who were not suspected of functional declines. The CRT consisted of a training period in which 12 items were presented, four at a time, with each item accompanied by a unique category cue. The testing phase consisted of three trials which generated two measures, a free recall score (FRS; spontaneous recall of the list of 12 items) and a total score (TS; FRS plus items recalled when the category cue was provided). It was found that a cut-off value of < or = 23 on the TS resulted in a sensitivity of 94.7% and a specificity of 93.9% with a positive predictive value of 81.9% when those individuals with DAT were compared to the participants with ID without DS. Eight of these individuals with DAT had relatively poor performance on the CRT compared to their healthy peers at a baseline when they were not suspected of functional declines, suggesting that memory declines can occur several years prior to the identification of DAT. In addition, 17 participants with DS without a diagnosis of DAT met the criterion for the cut-off score. Longitudinal data and converging measures indicated that there was the possibility that 15 of these individuals are in a 'pre-clinical' stage of decline. The usefulness of the CRT as a screening test for early memory deficits for this population needs to be confirmed by following these participants for an extended period of time and by studying an independent sample.

Diagnostic steps in Alzheimer dementia before treatment with new antidimentives

The dementia of the Alzheimer type (DAT) is a chronic neurodegenerative illness. It will continue to increase because of rising life expectancy in the industrialized countries. Apart from the physicians interest to treat, there is also an economically justified interest to reduce the disease progression in this group of patients. The main intention of the treating physicians is to keep their patients independent as long as possible. Up to now Alzheimer's disease can only be treated symptomatically. The verified diagnosis of DAT still depends on the neuropathological investigation of brain tissue. Therefore the clinical diagnosis of DAT during lifetime should be supported by chemical analysis of typical changes in the cerebrospinal fluid (CSF) at an early stage. Meanwhile, several therapeutics with proven effectiveness in clinical studies are certified for the symptomatic treatment of DAT. However, these therapeutics are still relatively expansive. Due to this fact the clinical diagnosis of DAT should be supported by clinical-chemical markers before the beginning of such a treatment. In this paper we present the diagnostic steps in dementia patients, who are examined in our departments. Patients suspicious of DAT always are asked for a spinal tap in addition to other diagnostic tools. In case of a typical clinical constellation, the exclusion of a primarily vascular dementia as well as the proof of decreased A beta 1-42 peptides and an increased tau protein in CSF we recommend the new drugs for DAT as meaningful and justified therapeutics to yield optimal treatment.

Temporal lobe magnetic resonance imaging can differentiate Alzheimer's disease from normal ageing, depression, vascular dementia and other causes of cognitive impairment.

Previous work suggests that temporal lobe magnetic resonance imaging (MRI) can distinguish those with dementia of the Alzheimer type (DAT) from healthy age-matched controls. However, its specificity with regard to conditions such as vascular dementia, depression and other disorders associated with cognitive impairment has not been determined. We studied 222 subjects using T1 weighted MRI with 5.1 mm coronal slices throughout the temporal lobe. Subjects included: healthy controls (N = 40); DSM-III-R major depression (N = 61); NINCDS/ADRDA DAT (N = 77) and OTHER (N = 44, comprising subjects with vascular dementia, Huntington's disease, schizophrenia, alcohol related cognitive impairment and a group of 'memory complainers'). Hippocampus, amygdala, entorhinal cortex, parahippocampal gyrus and cerebral cortex were rated visually on a 0-3 scale by two experienced neuroradiologists blind to clinical diagnosis. Ratings of temporal lobe atrophy provided good separation between those with AD and all other groups. For example, anterior hippocampal atrophy had a sensitivity of 83% for detecting DAT, a specificity of 80% for controls, 87% for depressed subjects and 89% for OTHER. Other regions were less sensitive, but more specific for the diagnosis of DAT. In particular parahippocampal gyrus and entorhinal cortex had high specificity (97% for depressed subjects and 98% for OTHER). Because of an age-related increase in atrophy, sensitivity was highest for those over the age of 75, while specificity was highest for younger subjects. Significant correlations were observed between atrophy ratings of hippocampus, amygdala, entorhinal cortex and parahippocampal gyrus and CAMCOG memory score and length of history. Temporal lobe MRI may have an important role in assisting with the clinical diagnosis of DAT, particularly its differentiation from depression and other disorders that may cause diagnostic difficulties in clinical practice.

A population-based analysis of qualitative features of the neuropsychological test performance of individuals with dementia of the Alzheimer type: Implications for individuals with questionable dementia.

Qualitative features of the neuropsychological test performance of individuals with dementia of the Alzheimer type (DAT) were examined in a population-based study. Qualitative error scores were derived from measures of verbal and figural memory, verbal fluency and confrontation naming for 38 patients with clinically diagnosed DAT, 236 normal elderly (NE) individuals, and 72 others who were questionably demented and at risk (AR) for DAT. Persons with DAT made a greater proportion of intrusion and perseverative errors, and more lexical and semantic naming errors, than the NE participants. These measures provided fair specificity but poor sensitivity for the diagnosis of DAT, and a logistic model based on these measures correctly classified 98% of the NE participants, but only 29% of the DAT participants. The AR participants demonstrated a pattern of errors that was highly similar to that of the DAT patients, and when their scores were subjected to the logistic model, 90% were classified as NE and 10% as DAT. These results indicate that specific error types that have been associated with DAT in self-referred or clinic-based samples also occur in the general population to a greater degree in individuals with DAT or questionable dementia than in NE individuals. Furthermore, these qualitative features may have some diagnostic usefulness in that their presence provides reasonable specificity for DAT or questionable dementia.

Delusions of theft in dementia of the Alzheimer type: a preliminary report.

Delusions of theft are commonly found in patients with dementia of the Alzheimer type (DAT). This report describes the frequency, onset, and characteristics of delusions of theft in DAT patients. The sample consisted of 54 geropsychiatric inpatients with DAT; delusions of theft were found in 30 (55.6%) patients. Two thirds of these patients had delusions of theft within 1 year after onset of illness. There were no significant differences in age, age of onset, duration of disease, years of education, or the Mini-Mental State Examination (MMSE) score between patients with and without delusions of theft. Delusions of theft frequently occur in the early stage of dementia, when the patients' cognitive impairments are relatively mild. The presence of this symptom may warrant a diagnosis of DAT.

Brain perfusion scintigraphy with99mTc-HMPAO or99mTc-ECD and123I-β-CIT single-photon emission tomography in dementia of the Alzheimer-type and diffuse Lewy body disease

Dementia of the Alzheimer-type (DAT) is characterized by progressive cognitive decline, variably combined with frontal lobe release signs, parkinsonian symptoms and myoclonus. The features of diffuse Lewy body disease (DLBD), the second most common cause of degenerative dementia, include progressive cognitive deterioration, often associated with levodopa-responsive parkinsonism, fluctuations of cognitive and motor functions, psychotic symptoms (visual and auditory hallucinations, depression), hypersensitivity to neuroleptics and orthostatic hypotension. A recent report suggests that positron emission tomography studies in patients with degenerative dementia may be useful in the differential diagnosis of DAT and DLBD. However, the diagnostic role of single-photon emission tomography (SPET) studies remains to be established. The aim of this study was therefore to evaluate regional cerebral perfusion [with either technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) or 99mTc-ethyl cysteinate dimer (99mTc-ECD) SPET] and striatal dopamine transporter density [using iodine-123 2 beta-carboxymethoxy-3 beta-[4-iodophenyl]tropane (123I-beta-CIT) SPET] in patients with DAT and DLBD. Six patients with probable DAT and seven patients with probable DLBD were studied. Blinded qualitative assessment by four independent raters of 99mTc-HMPAO or 99mTc-ECD SPET studies revealed bilateral temporal and/or parietal hypoperfusion in all DAT patients. There was additional frontal hypoperfusion in two patients and occipital hypoperfusion in one patient. In the DLBD group, regional cerebral perfusion had a different pattern. In addition to temporoparietal hypoperfusion there was occipital hypoperfusion resembling a horseshoe defect in six of seven patients. In the DAT group, the mean 3-h striatal/cerebellar ratio of 123I-beta-CIT binding was 2.5 +/- 0.4, with an increase to 5.5 +/- 1.1 18 h after tracer injection. In comparison, in the DLBD patients the mean 3-h striatal/cerebellar ratio of 123I-beta-CIT binding was significantly reduced to 1.7 +/- 0.3, with a modest increase to 2.1 +/- 0.4 18 h after tracer injection (P < 0.05, Scheffe test, ANOVA). These results suggest that 99mTc-HMPAO or 99mTc-ECD and 123I-beta-CIT SPET may contribute to the differential diagnosis between DAT and DLBD, showing different perfusion patterns and more severe impairment of dopamine transporter function in DLBD than in DAT.

Educational level and neuropsychological heterogeneity in dementia of the Alzheimer type.

We retrospectively assessed the data from 24 patients with dementia of the Alzheimer type (DAT) who underwent comprehensive neuropsychological evaluations in order to determine whether there is a relationship between neuropsychological heterogeneity and educational level. Postmortem neuropathological examination results were made available for seven cases, confirming the diagnosis of DAT. Thirteen patients had < or = 8 years of schooling (less educated subgroup), and the other 11 had > or = 8 years (higher educated subgroup). There were no significant differences between the two subgroups regarding age and duration of symptoms. Performance within each subgroup was compared with that of a specific set of education-matched elderly controls. In the less educated subgroup, 10 patients evidenced a homogeneous pattern of cognitive impairment, with all cognitive areas being similarly affected. Conversely, 10 higher educated patients had at least one cognitive area relatively preserved in comparison with the others, characterizing a heterogeneous pattern of impairment. These data suggest that a high level of education may lead to a greater capacity to compensate for neuronal damage and determines specific patterns of cognitive impairment in DAT.

Neuropsychological investigation of anterior and posterior cortical function in early-stage probable Alzheimer's disease.

In vivo neuroimaging studies have generally indicated a greater involvement of posterior cortical areas in early-stage dementia of the Alzheimer type (DAT) relative to frontal involvement. By contrast, some recent neuropsychological studies have shown that DAT patients perform poorly in frontal lobe tasks even in the early stages of the disease, although there is disagreement as to whether this necessarily implicates frontal pathology. The main aim of this study was to examine the hypothesis prompted by both neuroimaging studies and the traditional clinical conception of the disease, that, compared with the functioning of posterior association cortex, executive functions (thought to depend on frontal lobe integrity) are relatively spared in the early stages of DAT. A group of patients with a diagnosis of early-stage, probable DAT (n = 17) was compared with age- and IQ-matched controls (n = 17) across a range of neuropsychological tasks presumed to exercise frontal or temporoparietal functions. A profile of strengths and weaknesses was observed across 'anterior' and 'posterior' cognitive tests, including dissociations among some tests of temporoparietal function, in particular visual object perception (impaired) and spatial analysis skills (intact). Thus there was little support for the notion that the disease progresses cortically in a posterior-to-anterior direction. Possible reasons for the discrepancy between neurophysiological and neuropsychological observations are discussed, including the possibility that neuropsychological tests do not provide a valid indication of regional brain function when used in the context of DAT. Caution is urged in the clinical application of 'frontal lobe tests' for the differential diagnosis of DAT.

Neuropsychological Investigation of Anterior and Posterior Cortical Function in Early-Stage Probable Alzheimer’s Disease

In vivo neuroimaging studies have generally indicated a greater involvement of posterior cortical areas in early-stage dementia of the Alzheimer type (DAT) relative to frontal involvement. By contrast, some recent neuropsychological studies have shown that DAT patients perform poorly in frontal lobe tasks even in the early stages of the disease, although there is disagreement as to whether this necessarily implicates frontal pathology. The main aim of this study was to examine the hypothesis prompted by both neuroimaging studies and the traditional clinical conception of the disease, that, compared with the functioning of posterior association cortex, executive functions (thought to depend on frontal lobe integrity) are relatively spared in the early stages of DAT. A group of patients with a diagnosis of early-stage, probable DAT (n= 17) was compared with age- and IQ-matched controls (n= 17) across a range of neuropsychological tasks presumed to exercise frontal or temporoparietal functions. A profile of strengths and weaknesses was observed across ‘anterior’ and ‘posterior’ cognitive tests, including dissociations among some tests of temporoparietal function, in particular visual object perception (impaired) and spatial analysis skills (intact). Thus there was little support for the notion that the disease progresses cortically in a posterior-to-anterior direction. Possible reasons for the discrepancy between neurophysiological and neuropsychological observations are discussed, including the possibility that neuropsychological tests do not provide a valid indication of regional brain function when used in the context of DAT. Caution is urged in the clinical application of ‘frontal lobe tests’ for the differential diagnosis of DAT.

Measurement of severity in advanced Alzheimer's disease.

In late stages of dementia of the Alzheimer type (DAT), most scales measuring only cognitive or functional deficits lose their sensitivity to detect further disease progression. By combining ratings of cognitive (speech, eye contact) and functional deficits (dressing, eating, ambulation) with occurrence of pathological symptoms (sleep-wake cycle disturbance, muscle rigidity/contractures), a scale was developed (BANS-S) which does not lose its sensitivity until the patient reaches a vegetative state. BANS-S was tested on three Special Care Dementia Units. Data from 74 patients with the clinical diagnosis of DAT indicated that BANS-S has good reliability and reproducibility. BANS-S scores correlated with scores of Mini-Mental State Examination, Katz ADL, Test for Severe Impairment, and Language Assessment. In 25 patients with the diagnosis of DAT confirmed by autopsy, BANS-S scores determined within 3 months of death correlated with density of neurofibrillary tangles in CA2 and CA3 areas of the hippocampus. BANS-S may be a useful tool for the evaluation of different treatment strategies in severe DAT and for the correlation of clinical and pathological findings.

Use of MRI in the diagnosis of dementia of the Alzheimer type

MRI of 31 patients with dementia of the Alzheimer type (DAT) (mean age 74.7 years) were studied to detect characteristic findings, and compared with those of 24 normal elderly controls (mean age 74.1 years). Atrophy was quantitated by planimetric and linear measurements, and periventricular and deep white matter signal abnormalities were assessed by subjective ratings. Although we observed significant differences between the DAT patients and controls, there was overlap in each of the measurements. Of these, the ratio of the temporal horn area and the pattern of linear measurements (the width of the temporal horn body--the medial temporal lobe width--the interuncal distance) best distinguished the DAT patients from controls. Twenty-five patients (81%) had a ratio of the temporal horn area larger than the value of the mean + 2SD of the controls. AV-shaped pattern, in which the medial temporal lobe width was smaller than the other two values, was demonstrated in 84% of the patients and only 8% of the controls. Although signal abnormalities were not useful for diagnostic purposes, periventricular hyperintensities were more commonly seen in the DAT patients than in the controls, and correlated with cognitive function. MRI studies suggest that the assessment of medial temporal lobe atrophy is useful in the diagnosis of DAT, and periventricular hyperintensity may be related in some way to the disease process.

Longitudinal changes in lateral ventricular volume in patients with dementia of the Alzheimer type.

We determined the rates of lateral ventricular enlargement and decline in cognitive performance for 11 men and nine women with dementia of the Alzheimer type (DAT), and compared these rates with the same measures obtained for age-matched healthy controls (nine men and eight women). DAT patients, as a group, had only mild cognitive impairment at initial evaluation, and each patient was followed from 9 months to over 7 years with yearly evaluations. Six DAT patients had isolated memory impairment as their only cognitive deficit early in the course of the disease. The rate of total lateral ventricle enlargement (cm3/yr) was significantly different between DAT and healthy controls, and was more specific and sensitive to the diagnosis of DAT than comparison of cross-sectional volumes at final evaluation. The rate of total lateral ventricular enlargement did not differ significantly by patient sex, ventricular size at initial evaluation, age, or degree of cognitive impairment as measured by Mini Mental State Examination scores. However, in the six DAT patients initially found to have isolated memory impairment, the rate of ventricular enlargement during the period of isolated memory impairment was significantly less than the rate of ventricular enlargement after the onset of nonmemory cognitive impairment. The diagnostic power of total lateral ventricular measures made from two CTs separated by 1 year and obtained early in the course of the illness, however, was only 0.33. We conclude that the total lateral ventricular enlargement accompanying DAT is due to continuous, pathologic cell loss, significantly greater than cell loss due to the healthy aging process.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonneural markers in Alzheimer disease.

Nonneural tissues are now widely used to search for abnormalities in genes as well as for other markers of dementia of the Alzheimer type (DAT). Studies of nonneural tissues can experimentally circumvent problems inherent in the study of autopsy brain, but to be meaningful, abnormalities identified in the periphery must be correlated with abnormalities in the brain, which is the tissue of clinical interest. Among the topics in DAT research that can be readily studied in nonneural cells (including tissue cultures) are molecular genetics, amyloid precursor protein formation and metabolism, systemic manifestations of immunological and inflammatory mechanisms, proteolysis, membranes, signal transduction, and mitochondria and metabolism. Although phenomena suggesting the possibility of cytoskeletal abnormalities in nonneural DAT cells have been described, the tau molecules involved in paired helical filament formation are relatively brain-specific. Since the neuropathological diagnosis of DAT depends on recognizing a pattern of changes rather than any single abnormality, it seems unlikely that any one laboratory abnormality in peripheral tissues will correlate precisely with the clinicopathological entity of DAT. However, abnormalities found in nonneural DAT cells that correlate with the existence of similar abnormalities in the brain are likely to be informative about the disease process in the patients in whom they occur.

MR‐based hippocampal volumetry in the diagnosis of Alzheimer's disease

We evaluated a new magnetic resonance (MR)-based technique for performing volumetric measurements of temporal lobe structures. The technique was designed to assist in making the clinical diagnosis of dementia of the Alzheimer type (DAT). We chose specific anatomic regions of interest because of their known involvement in memory function and in the neuropathology of DAT and used a regression model to assess the effects of age on the volumes of the anterior temporal lobe (ATL) and the hippocampal formation (HF). These measurements were normalized by total intracranial volume (TIV). The volumetric measurements of both the normalized ATL and HF were significantly smaller (p less than 0.001) in DAT patients (N = 20) than in controls (N = 22), but the HF volumes provided much better separation between the two groups. Eighty-five percent of the DAT patients fell below the range of the HF/TIV measurement for the control subjects. This separation held up over the entire age range studied. Normalized volumes of both the HF and ATL decreased with age significantly for both the DAT patients and the controls. These results support the contention that MR-based HF volumetric measurements are accurate in differentiating DAT patients from cognitively normal elderly individuals. This technique may be a useful adjunct in making the clinical diagnosis of DAT.

Neuropsychological Effects of L-Deprenyl in Alzheimerʼs Type Dementia

The monoaminergic neurotransmission defect seen in dementia of the Alzheimer type (DAT) is linked to a known increased activity of type B cerebral monoamine oxidases (MAO-Bs). The use of drugs that are able to block this abnormal activity could therefore be useful in the treatment of some cognitive deficits that characterize DAT. Twenty patients with a clinical diagnosis of DAT and with a slight-moderate mental deterioration were treated with 10 mg/day of L-deprenyl, a selective MAO-B inhibitor, according to a double-blind crossover design vs. placebo. Initial treatment (drug or placebo) was randomly assigned. The patients' cognitive functions were evaluated at baseline and then after 3 and 6 months of treatment with drug or placebo. The patients crossed over treatment after 3 months, without a washout interval. The results of the study show the higher and statistically significant effects of L-deprenyl on memory and attention that seem to be due to an improved function of the monoaminergic systems involved in the process of neuronal degeneration.

Reactive microglia are positive for HLA-DR in the substantia nigra of Parkinson's and Alzheimer's disease brains.

We detected large numbers of HLA-DR-positive reactive microglia (macrophages), along with Lewy bodies and free melanin, in the substantia nigra of all cases studied with Parkinson's disease (5) and parkinsonism with dementia (PD) (5). We found similar, but less extensive, pathology in the substantia nigra of six of nine cases of dementia of the Alzheimer type (DAT) but in only one of 11 age-matched nonneurologic cases. All dementia cases with a premortem diagnosis of DAT or PD showed large numbers of HLA-DR-positive reactive microglia and significant plaque and tangle counts in the hippocampus, as well as reduced cortical choline acetyltransferase activity. One of 11 nondemented controls showed mild evidence of similar cortical pathology. These data indicate that HLA-DR-positive reactive microglia are a sensitive index of neuropathologic activity. They suggest a frequent coexistence of DAT- and Parkinson-type pathology in elderly patients.

Loss of hippocampal [ 3H]TCP binding in Alzheimer's disease

We have previously demonstrated a marked loss in N- methyl- d-aspartate (NMDA) receptors in the hippocampus and cerebral cortex of patients dying with dementia of the Alzheimer type (DAT). In addition, we have found that the dissociative anesthetic N-(1-[2-thienyl]cyclohexyl)3,4-piperidine ([ 3H]TCP) binds to a site whose regional distribution is highly correlated with that of NMDA receptor sites. We studied the binding of [ 3H]TCP to sections of hippocampi from 8 controls, 12 patients with DAT and 7 patients with other dementias. [ 3H]TCP binding was significantly reduced in strata pyramidalia of CA 1/CA 2, CA 3 and subiculum of DAT hippocampal formation compared to that of control. Labelled dissociative anestheties could potentially be used with positron emission tomography in the diagnosis of DAT.