Biomedical subjects

Klaus Schmidtke

Publications and source records attributed to Klaus Schmidtke.

7 recordsLinked to original sources

PubMed2006

The Clock Reading Test: validation of an instrument for the diagnosis of dementia and disorders of visuo-spatial cognition.

BACKGROUND: The 12-item Clock Reading Test (CRT) allows a fine-graded assessment of clock-reading ability. It has a strong focus on visuo-spatial processing and requires no executive processing. This study evaluated the reliability, validity, sensitivity and specificity of the CRT for the diagnosis of dementia and visuo-spatial dysfunction. METHODS: The CRT, the Clock Drawing Test (CDT) and other tests were applied to groups of 200 subjects with dementia, 105 subjects with mild cognitive impairment (MCI), 20 subjects with focal parietal lesions and 64 elderly control subjects. RESULTS: The CRT was found to be reliable and sensitive for the detection of cognitive impairment in parietal lesions, Alzheimer-, mixed- and Lewy Body dementia. Normal subjects and patients with MCI, frontotemporal dementia or cerebral small vessel disease showed little or no impairment. CONCLUSION: CRT and CDT are clock-processing tests with different demand profiles. They can supplement each other in the neuropsychological diagnosis of dementia and visuo-spatial dysfunction.

Aged↗

PubMed2005

Cerebral small vessel disease: how does it progress?

Small vessel disease (SVD), or microangiopathy, of the cerebral white and central grey matter is an important subtype of vascular dementia (VD). SVD-dementia is characterised by a "dysexecutive" type of cognitive impairment, neurological deficits including imbalance and voiding dysfunction, and emotional disturbances. SVD is also frequent among clinically healthy subjects and patients with mild cognitive impairment. It is easily visualised by imaging techniques, but difficult to distinguish from mixed SVD/Alzheimer Disease. SVD has an inherent tendency to progress, but data on its natural course are sparse, and there are almost no drug trials dedicated to it. This article reviews the evidence on the speed and predictors of progression of SVD in regard to cognitive deficits, functional decline and white matter lesions, as derived from epidemiological, clinical and imaging studies and the placebo branches of VD drug trials. Based on the available data, we make suggestions for future research and outcome measures.

Animals↗

PubMed2005

Posterior cortical atrophy: variant of Alzheimer's disease? A case series with PET findings.

Nine patients with posterior cortical atrophy (PCA), a rare degenerative brain disease of unclear etiology and nosology, were followed over a mean time of 7.4 years. The mean age at onset was low (56.2 years). At onset, eight patients had visuo-spatial and eight had memory impairment. A minority showed early signs of occipital lobe involvement with visual agnosia or hemianopia. Eight patients developed dementia after a mean course of five years. 18F-FDG-PET data of six patients were analysed with statistical parametric mapping. They showed hypometabolism centred on the lateral and medial parietal associative cortex, with variable involvement of the adjacent temporal and occipital associative cortex. A minority showed involvement of the frontal lobes, possibly related to deafferenting of areas related to the control of eye movements. Atrophy and hypometabolism were markedly asymmetric in a subset of cases. Autopsy was performed in one patient. Presenile onset, location, and asymmetry of atrophy suggest that PCA represents a biologically separable variant of Alzheimer's disease.

Adult↗

PubMed2005

Multiple chemical sensitivity syndrome (MCS)--suggestions for an extension of the U.S. MCS-case definition.

PURPOSE: To validate and extend the US case definition for the Multiple Chemical Sensitivity Syndrome (MCS) from 1999 by a systematic literature-review. DATA SOURCE: MEDLINE-research from 1997 to August 2003, research in the Cochrane-Library in August 2003, earlier reviews since 1997. STUDY SELECTION: Headings and abstracts were screened by one reviewer. All references dealing with multiple chemical sensitivities (MCS) which covered topics of interest such as symptom-profiles, differential diagnostic procedures, etc. were included in the analysis. DATA EXTRACTION AND SYNTHESIS: Topic-specific data extraction and synthesis was done by one reviewer. Data interpretation was discussed by all other authors. RESULTS: Out of 1429 references 36 publications proved to be suitable for the review. The results can be summarized as follows: exposure-related symptoms associated with self-reported multiple chemical sensitivities can be divided into non-specific complaints of the central nervous system--CNS (main characteristics) and functional disturbances in other organ systems (optional complaints). There is a significant overlap of MCS, CFS and fibromyalgie. At present no standards for a diagnostic procedure based on the criteria outlined above are existing CONCLUSIONS: MCS should only be diagnosed in patients who are mainly suffering from exposure-related non-specific complaints of the Central nervous system. The suggested diagnostic procedure follows the guidelines for CFS which are extended by diagnostic clarification of functional disturbances in other organ systems.

Data Collection↗

PubMed2002

Neuropsychological differentiation of small vessel disease, Alzheimer's disease and mixed dementia.

This study examined the neuropsychological profile of probable Alzheimer's disease (AD, n=72), vascular dementia due to diffuse subcortical small vessel disease (SVD, n=18) and mixed dementia (AD+SVD, n=18). Five simple tests were analysed, i.e. verbal recall and recognition memory, object naming, word fluency and clock reading. Pairwise discriminant analyses classified 79-83% of the cases correctly. Mixed dementia (MD) patients showed lower word fluency; otherwise, their profile was indistinguishable from AD. Recognition memory and clock reading were identified as predictors of SVD vs. AD diagnosis. The potential of single variables to distinguish the groups was tested by receiver operator characteristic curve analysis. A clock reading cut-off score close to maximum separated SVD from AD and MD. Recognition memory separated SVD from AD. These results show that neuropsychological tests can distinguish SVD and MD from AD with high sensitivity (88-94%). Due to the overlapping of scores and a higher prevalence of AD, specificity was moderate (65-76%) and positive predictive values were low, whereas sensitivity and negative predictive indices were high.

Aged↗

PubMed2002

On the role of quantitative brain imaging in the differential diagnosis of speech disorders.

We present the case of a 71-year-old woman with an 11-year history of slowly progressive decline of motor speech. Normal clinical investigations including routine magnetic resonance imaging (MRI) at 7, 8 and 10 years after the onset of speech dysfunction led to the suggestion of a psychogenic disorder. Extensive clinical, neuropsychological and neuroimaging investigations including 18F-desoxyglucose-positron emission tomography (PET), quantitative MRI and MR spectroscopy were performed to look for subtle brain pathology. Quantitative assessment of 3D-MRI, F-desoxyglucose-PET and magnetic resonance spectroscopy all demonstrated clear evidence of multifocal frontotemporal brain pathology that had not been picked up on routine MRI investigations on previous admissions. This is the longest benign history of slowly progressive anarthria reported so far. It demonstrates a possible role of quantitative neuroimaging techniques in the diagnosis of complex neuropsychiatric disorders.

Aged↗

PubMedDate not supplied

Cognitive procedural learning in patients with fronto-striatal lesions.

Previous studies on the role of prefronto-striatal loop systems for cognitive procedural learning (PL) brought inconsistent results. To examine whether the integrity of the dorsolateral prefrontal loop is indispensable for normal cognitive PL, we examined the acquisition of cognitive skills in 35 patients with focal prefrontal lesions, focal caudate lesions, and Huntington's Disease (HD), and compared it with a control group. To examine the potential role of the processing demands made by the cognitive tasks, a set of tasks was applied whose acquisition places demand either on reasoning and problem solving, or on the establishment of fast and repetitive processing routines. The Pursuit Rotor task was also studied with the aim to re-examine earlier findings of a functional segregation of motor and complex prefronto-striatal loops. Deficits of cognitive and motor PL were found to be limited to certain tasks and groups. PL of one task, which demanded rapid, repetitive processing of visuo-spatial stimuli, was impaired in all patient groups. PL of two problem-solving tasks was impaired in patients with focal and degenerative caudate lesions only. None of the groups was impaired at PL of Mirror Reading, another task demanding rapid and repetitive visuo-spatial processing, and none was impaired in a fifth task of language skill. Deficits of motor learning were only observed in patients in whom the motor loop was affected. These results suggest that the dorsolateral prefronto-striatal loop is involved in the establishment of cognitive processing routines. The comparison of patients with and without caudate lesions suggests that disconnection of this circuit is critical. However, the normal acquisition of two cognitive tasks even in this group indicates that the integrity of the dorsolateral prefrontal loop is not mandatory for normal cognitive PL. We discuss these dissociations with regard to the demand profiles of the applied tasks and the locations of the lesions.

Adult↗