Frontal-executive constructional apraxia: when delayed recall is better than copying

The Use of Verbal and Nonverbal Memory Tests for Alzheimer's Disease Screening in Taiwan Chinese

Patients with Alzheimer's disease typically have initial deficits in memory. Memory testing can be categorized as verbal or nonverbal by the modality of the stimuli used. We compared the discriminative validity of selected verbal and nonverbal memory tests between non-dementia and Alzheimer's disease in Taiwan. Ninety-eight patients with mild Alzheimer's disease and 269 non-dementia individuals underwent story recall test (immediate and delayed recall), and constructional praxis test (copy and delayed recall). The receiver-operating characteristic curve and area under the curve were evaluated to compare between tests. Patients with Alzheimer's disease performed poorly across all memory tests, and the receiver-operating characteristic curve analysis indicated that story recall immediate and relayed recall, and constructional praxis delayed recall had good classification accuracy with area under the curve of .90, .87 and .87 respectively. These results provide support that both verbal and nonverbal memory tests are reliable measure for screening patients with Alzheimer's disease.

Psychological and Cognitive Markers of Behavioral Variant Frontotemporal Dementia-A Clinical Neuropsychologist's View on Diagnostic Criteria and Beyond

Behavioral variant frontotemporal dementia (bvFTD) is the second leading cognitive disorder caused by neurodegeneration in patients under 65 years of age. Characterized by frontal, insular, and/or temporal brain atrophy, patients present with heterogeneous constellations of behavioral and psychological symptoms among which progressive changes in social conduct, lack of empathy, apathy, disinhibited behaviors, and cognitive impairments are frequently observed. Since the histopathology of the disease is heterogeneous and identified genetic mutations only account for ~30% of cases, there are no reliable biomarkers for the diagnosis of bvFTD available in clinical routine as yet. Early detection of bvFTD thus relies on correct application of clinical diagnostic criteria. Their evaluation however, requires expertise and in-depth assessments of cognitive functions, history taking, clinical observations as well as caregiver reports on behavioral and psychological symptoms and their respective changes. With this review, we aim for a critical appraisal of common methods to access the behavioral and psychological symptoms as well as the cognitive alterations presented in the diagnostic criteria for bvFTD. We highlight both, practical difficulties as well as current controversies regarding an overlap of symptoms and particularly cognitive impairments with other neurodegenerative and primary psychiatric diseases. We then review more recent developments and evidence on cognitive, behavioral and psychological symptoms of bvFTD beyond the diagnostic criteria which may prospectively enhance the early detection and differential diagnosis in clinical routine. In particular, evidence on specific impairments in social and emotional processing, praxis abilities as well as interoceptive processing in bvFTD is summarized and potential links with behavior and classic cognitive domains are discussed. We finally outline both, future opportunities and major challenges with regard to the role of clinical neuropsychology in detecting bvFTD and related neurocognitive disorders.

Constructional apraxia

Since the classic papers of Kleist, Mayer Gross, and Critchley, constructional apraxia (CA) has been considered to be a typical sign of a parietal lobe lesion, and as a precious tool to appreciate the spatial abilities subserved by this lobe. However, the development of more sophisticated neuropsychologic models and methods of investigation has revealed several problematic aspects. It has become increasingly clear that CA is a heterogeneous construct that can be examined with very different tasks, that are only mildly interconnected, and tap various kinds of visuospatial, perceptual, attentional, planning, and motor mechanisms. On the basis of these considerations, the relationships between parietal lobe functions and constructional activities must be considered, taking into account on the one hand the heterogeneity of the tasks and of the cognitive functions requested by different kinds of constructional activities and, on the other hand, the plurality of functions and of processing streams linking different parts of the parietal lobes to the occipital and frontal lobes.

Drawing Disorders in Alzheimer's Disease and Other Forms of Dementia

Drawing is a multicomponential process that can be impaired by many kinds of brain lesions. Drawing disorders are very common in Alzheimer's disease and other forms of dementia, and can provide clinical information for the distinction of the different dementing diseases. In our review we started from an overview of the neural and cognitive bases of drawing, and from a recollection of the drawing tasks more frequently used for assessing individuals with dementia. Then, we analyzed drawing disorders in dementia, paying special attention to those observed in Alzheimer's disease, from the prodromal stages of the amnesic mild cognitive impairment to the stages of full-blown dementia, both in the sporadic forms with late onset in the entorhino-hippocampal structures and in those with early onset in the posterior neocortical structures. We reviewed the drawing features that could differentiate Alzheimer's disease from vascular dementia and from the most frequent forms of degenerative dementia, namely frontotemporal dementia and Lewy body disease. Finally, we examined some peculiar aspects of drawing disorders in dementia, such as perseverations, rotations, and closing-in. We argue that a careful analysis of drawing errors helps to differentiate the different forms of dementia more than overall accuracy in drawing.