Objectives– To propose a neuropsychological study of the various aspects of self‐consciousness (SC) in Alzheimer's disease. Methods– Forty‐five patients with probable mild or moderate AD were included in the study. Severity of their dementia was assessed by the Mini Mental State (MMS). Fourteen questions were prepared to evaluate SC. Results– No significant correlations were found between SC score and educational level, age, and duration of disease. A significant correlation was found between SC score and the severity of dementia, whereas frontal disturbances were just short of the significance threshold. The various aspects of SC were not impaired to the same degree. The most disturbed ones were awareness of cognitive deficiencies, moral judgements and prospective memory. The least disturbed aspects were awareness of identity and of mental representation of the body. Items relating to anosognosia and moral judgements were significantly correlated with the MMS score, whereas affective state, body representation disorders, prospective memory, and capacities for introspection were not related to the severity of the dementia. Consciousness of identity was sound, regardless of MMS score. Conclusions– AD clearly induces an heterogeneous impairment of SC. SC requires a convergence of many neural networks. In AD, neuronal alterations involve many cortical areas and information sent to the associative frontal cortex from memory, language and visuospatial areas is lacking or disturbed. Thus, the sequential order of successive stimuli cannot be maintained by the heteromodal associative cortex (dorsal convexity of the prefrontal cortex), and the supramodal associative cortex (located rostrally in the frontal lobes) is unable to provide reliable monitoring and assessment of simultaneous neural cognitive networks carrying insufficient and inadequate input. The core deficiency in AD patients might be impaired SC equated with the disability to maintain sequential and simultaneous “attention to life”. The Self‐Consciousness Questionnaire, a clinical scale providing multidimensional measurement, indicates that different aspects of consciousness are not correlated with overall cognitive deficiency as determined by the MMSE.
The pattern of deficits observed in isolated cerebellar infarcts highlights the nonmotor functions of the cerebellum and functional relationship between the cerebral cortex and the cerebellum.
The study explored executive dysfunction in Parkinson's disease (PD) by using the Hayling test (Burgess & Shallice, 1996) and verbal fluency tasks (VFTs). PD patients showed longer response latencies than controls in both parts of the Hayling test (Section A/automatic and Section B/inhibition). Patients and controls did not differ in the proportion of errors or number of responses that revealed the use of strategies. PD patients also showed verbal fluency deficits in semantic, phonemic, and alternating fluency tasks. These impairments on tests known to be sensitive to frontal lobe dysfunction confirm executive or Supervisory Attentional System (Norman & Shallice, 1986) deficits and further indicate suppression skills impairments in PD.
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