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Philip Scheltens

Publications and source records attributed to Philip Scheltens.

79 records · Page 5Linked to original sources
PubMed2002

Diagnostic accuracy of the Preclinical AD Scale (PAS) in cognitively mildly impaired subjects.

The Preclinical AD Scale (PAS) is a newly developed scale for the diagnosis of preclinical Alzheimer's disease (AD). The PAS combines six markers of preclinical AD, namely age, MMSE score, functional impairment, cognitive test performance, medial temporal lobe atrophy, and the apolipoprotein E (APOE) genotype. The aim of the study was to investigate whether the PAS can accurately identify subjects with preclinical AD who become demented during a 2 or 5 year follow-up from among subjects with mild cognitive impairment for other reasons. We also investigated whether a step-wise scoring of the PAS could reduce the number of elaborate or expensive diagnostic procedures. The PAS was scored retrospectively in two independent samples of non-demented subjects with mild cognitive impairment older than 55 years (average age 65.6 years), who were selected from a memory clinic population. In the first sample, the follow-up was 5 years (5-year follow-up sample; n=69). In the second sample, the follow-up was 2 years (2-year follow-up sample; n=23). The PAS item medial temporal lobe atrophy was not scored in the 5-year follow-up sample. A PAS cut-off score of 4/5 could best identify subjects with AD-type dementia at follow-up (n=25) in the 5-year follow-up sample with a sensitivity of 80% and a positive predictive value of 77%. A PAS cut-off score of 5/6 could best identify subjects with AD-type dementia at follow-up (n=8) in the 2-year follow-up sample with a sensitivity of 88% and a positive predictive value of 70%. The positive predictive value could be increased to 94% in the 5-year follow-up sample and to 80% in the 2-year follow-up sample by using higher cut-off scores, but this reduced the sensitivity. Step-wise scoring of the PAS had the same diagnostic accuracy as the total PAS score and reduced the number of cognitive assessments by 22 to 38%, the number of assessments of medial temporal lobe atrophy by 57 to 74%, and the number of APOE genotypings by 74%. It is concluded that the PAS is a useful scale to identify subjects with preclinical AD who will become demented during the next 2 or 5 years. Step-wise scoring of the PAS can reduce the number of elaborate or expensive diagnostic procedures considerably.

Aged↗
PubMed2002

Structural magnetic resonance imaging in the practical assessment of dementia: beyond exclusion.

Neuroimaging is increasingly used to aid diagnosis in dementia. The traditional view that imaging is important solely as means of excluding treatable causes of dementia is maintained by many guidelines. These conditions however, account for a tiny proportion (<1%) of all causes of dementia. Over the past few years it has been recognised that a more accurate diagnosis and prognosis is important for patients and their families. The different pathological processes that produce cerebral dysfunction at a cellular level also produce macroscopic effects that can be detected in vivo with imaging. Clinically useful measures that distinguish between neurodegenerative disorders at an early stage are still awaited. The most likely future use of structural imaging will be the identification of patients at risk for Alzheimer's disease or with preclinical Alzheimer's disease. For magnetic resonance imaging (MRI) this will mean focusing on those areas that are affected earliest in the disease; ie, entorhinal cortex and hippocampus, using high resolution structural MRI or sophisticated brain mapping techniques. Imaging research is also likely to focus on measuring progression and detecting therapeutic effect. As such, MRI is already become an indispensable tool in clinical trials in dementia.

Brain↗
PubMed2002

Generalized synchronization of MEG recordings in Alzheimer's Disease: evidence for involvement of the gamma band.

The purpose of this study was to investigate interdependencies in whole-head magnetoencephalography (MEG) of Alzheimer patients and healthy control subjects. Magnetoencephalograms were recorded in 20 Alzheimer patients (11 men; mean age, 69.0 years [standard deviation, 8.2 years]); Mini-Mental State Examination score, 21.3 points; range, 15 to 27 points) and 20 healthy control subjects (9 men; mean age, 66.4 years [standard deviation, 9.0 years]) during a no-task eyes-closed condition with a 151 channel whole-head MEG system. Synchronization likelihood (a new measure for linear as well as nonlinear interdependencies between signals) and coherence were computed for each channel in different frequency bands (2 to 6, 6 to 10, 10 to 14, 14 to 18, 18 to 22, 22 to 40 Hz). Synchronization was lower in Alzheimer patients in the upper alpha band (10 to 14 Hz), the upper beta band (18 to 22 Hz), and the gamma band (22 to 40 Hz). In contrast, coherence did not show significant group differences at the p<0.05 level. The synchronization likelihood showed a spatial pattern (high synchronization central, parietal and right frontal; low synchronization, occipital and temporal). This study confirms a widespread loss of functional interactions in the alpha and beta bands, and provides the first evidence for loss of gamma band synchronization in Alzheimer's disease. Synchronization likelihood may be more sensitive to detect such changes than the commonly used coherence analysis.

Aged↗
PubMed2002

Imaging of white matter lesions.

Magnetic resonance imaging (MRI) is very sensitive for the detection of white matter lesions (WML), which occur even in normal ageing. Intrinsic WML should be separated from physiological changes in the ageing brain, such as periventricular caps and bands, and from dilated Virchow-Robin spaces. Genuine WML are best seen with T2-weighted sequences such as long TR dual-echo spin-echo or FLAIR (fluid-attenuated inversion recovery); the latter has the advantage of easily separating WML from CSF-like lesions. Abnormal T2 signal in MRI is not specific, and can accompany any change in tissue composition. In the work-up of WML in small vessel disease, magnetic resonance angiography can be used to rule out (concomitant) large vessel disease, and diffusion-weighted MRI to identify new ischaemic lesions (amidst pre-existing old WML). The differential diagnosis of WML includes hereditary leukodystrophies and acquired disorders. The leukodystrophies that can present in adult age include metachromatic leukodystrophy, globoid cell leukodystrophy, adrenomyeloneuropathy, mitochondrial disorders, vanishing white matter, and cerebrotendinous xanthomatosis. These metabolic disorders typically present with symmetrical abnormalities that can be very diffuse, often with involvement of brainstem and cerebellum. Only the mitochondrial disorders tend to be more asymmetric and frequently involve the grey matter preferentially. Among the acquired white matter disorders, hypoxic-ischaemic causes are by far the most prevalent and without further clinical clues there is no need to even consider the next most common disorder, i.e. multiple sclerosis (MS). Among the nonischaemic disorders, MS is far more common than vasculitis, infection, intoxication and trauma. While vasculitis can mimic small vessel disease, MS has distinctive features with preferential involvement of the subcortical U-fibres, the corpus callosum, temporal lobes and the brainstem/cerebellum. Spinal cord lesions are very common in MS, but do not occur in normal ageing nor in small vessel disease.

Aged↗
PubMed2002

Effects of transcutaneous electrical nerve stimulation (TENS) on non-pain related cognitive and behavioural functioning.

An extensive search through nine electronic bibliographic databases (PubMed, Cochrane Library, Web of Science, ERIC, PsychINFO, Psyndex, Cinahl, Biological Abstracts, Rehabdata) was performed in order to review the effects of Transcutaneous Electrical Nerve Stimulation (TENS) on non-pain related cognitive and behavioural functioning. Eight studies were identified on neglect due to stroke, six studies on Alzheimer's disease (AD), one study on aging, and two studies on coma due to traumatic brain injury. The results of the various studies revealed that TENS has a variety of effects. These consist of enhancement of somatosensory functioning, visuo-spatial abilities and postural control in neglect, improved memory, affective behaviour and rest-activity rhythm in AD and acceleration of awakening in coma. Effectiveness of TENS is discussed in relation to various stimulation parameters: duration, frequency, pulse width and intensity. It is argued that arousal may underlie the beneficial influence of TENS in various conditions. Finally, suggestions are offered for future research.

Adolescent↗
PubMed2002

Head trauma and Alzheimer's disease.

The authors describe a case of a 55 year old woman who was diagnosed with Alzheimer's disease 1.5 years after a car accident in which she experienced a mild concussion. Extensive history taking disclosed no cognitive changes prior to the car accident. The case is discussed in view of the inflammation hypothesis regarding Alzheimer's disease and the role of the apolipoprotein E4 genotype of the patient.

Alzheimer Disease↗