Applause sign in Alzheimer's disease: relationships to cognitive profile and severity of illness.

The present study aims to investigate the potential clinical utility of applause sign in Alzheimer's disease (AD), exploring whether it is consequent to the severity of cognitive impairment or to specific neuropsychological profiles. According to the current debate, the role of apraxia is also investigated. A total of 105 patients with AD were enrolled and classified on the basis of the severity of the disease: 37 had mild AD, 38 moderate AD, and 30 severe AD. They were compared to 42 normal subjects. The applause sign was detected using the three clap test. All patients underwent a broad neuropsychological examination and 95 AD patients were tested for the presence of apraxia with a detailed praxis battery. Applause sign was present in all AD patient groups, which showed a significant difference with respect to normal controls, but not between each other. No significant difference was reported between apraxic and non-apraxic patients. Applause sign correlated with measures of frontal lobe dysfunction. No correlations were found between the applause sign and other cognitive functions examined.

Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference.

Impairment on standard tests of delayed recall is often already maximal in the aMCI stage of Alzheimer's Disease. Neuropathological work shows that the neural substrates of memory function continue to deteriorate throughout the progression of the disease, hinting that further changes in memory performance could be tracked by a more sensitive test of delayed recall. Recent work shows that retention in aMCI patients can be raised well above floor when the delay period is devoid of further material - 'Minimal Interference'. This memory enhancement is thought to be the result of improved memory consolidation. Here we used the minimal interference/interference paradigm (word list retention following 10 min of quiet resting vs. picture naming) in a group of 17 AD patients, 25 aMCI patients and 25 controls. We found (1) that retention can be improved significantly by minimal interference in patients with aMCI and patients with mild to moderate AD; (2) that the minimal interference paradigm is sensitive to decline in memory function with disease severity, even when performance on standard tests has reached floor; and (3) that this paradigm can differentiate well (80% sensitivity and 100% specificity) between aMCI patients who progress and do not progress to AD within 2 years. Our findings support the notion that the early memory dysfunction in AD is associated with an increased susceptibility to memory interference and are suggestive of a gradual decline in consolidation capacity with disease progression.

Non-verbal memory measured by Rey-Osterrieth Complex Figure B: normative data.

One of the major problems that clinical neuropsychology has had in memory clinics is to apply ecological, easily administrable and sensitive tests that can make the diagnosis of dementia both precocious and reliable. Often the choice of the best neuropsychological test is hard because of a number of variables that can influence a subject's performance. In this regard, tests originally devised to investigate cognitive functions in healthy adults are not often appropriate to analyze cognitive performance in old subjects with low education because of their intrinsically complex nature. In the present paper, we present normative values for the Rey-Osterrieth Complex Figure B Test (ROCF-B) a simple test that explores constructional praxis and visuospatial memory. We collected normative data of copy, immediate and delayed recall of the ROCF-B in a group of 346 normal Italian subjects above 40 years. A multiple regression analysis was performed to evaluate the potential effect of age, sex, and education on the three tasks administered to the subjects. Age and education had a significant effect on copying, immediate recall, and delayed recall as well as on the rate of forgetting. Correction grids and equivalent scores with cut-off values relative to each task are available. The availability of normative values can make the ROCF-B a valid instrument to assess non-verbal memory in adults and in the elderly for whom the commonly used ROCF-A is too demanding.

Dissociation apraxia secondary to right premotor stroke.

Apraxia is usually associated with damage to the dominant parietal cortex, but several other areas, including the left dorsolateral frontal cortex and subcortical structures, have also been implicated, suggesting that the praxis system is mediated by an anatomically distributed network. The right premotor frontal cortex is commonly assumed to play a secondary role in this system. We describe a patient who developed left upper limb apraxia after a right premotor ischaemic stroke. The neuropsychological examination ruled out impairment of other cognitive functions, including those subserved by the parietal-temporal cortex. Neither pyramidal signs nor interhemispheric transfer syndrome were detected, suggesting that the right primary motor cortex and corpus callosum were intact and that apraxia arose from a right prefrontal cortical lesion. An additional feature was the patient's inability to copy a gesture or posture demonstrated by the examiner (visual input) or to execute a verbal command (auditory input), even though he could copy the position in which the examiner placed his right arm while blindfolded (proprioceptive input). The disturbance was interpreted as "dissociation apraxia". To our knowledge this type of dissociation has never been reported in a patient with focal brain damage. The case of this patient highlights the importance of the right premotor cortex in the praxis system, and lends support to the hypothesis of a modular and multimodal organization of brain functioning.