Self-consciousness and Alzheimer's disease

Objectives - To propose a neuropsychological study of the various aspects o f self-consciousness (SC) in Alzheimer's disease. Methods Forty-five patien ts with probable mild or moderate AD were included in the study. Severity o f their dementia was assessed by the Mini Mental State (MMS). Fourteen ques tions were prepared to evaluate SC. Results - No significant correlations w ere found between SC score and educational level, age, and duration of dise ase. A significant correlation was found between SC score and the severity of dementia, whereas frontal disturbances were just short of the significan ce threshold. The various aspects of SC were not impaired to the same degre e. The most disturbed ones were awareness of cognitive deficiencies, moral judgements and prospective memory. The least disturbed aspects were awarene ss 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 sco re. 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 fronta l cortex from memory, language and visuospatial areas is lacking or disturb ed. Thus, the sequential order of successive stimuli cannot be maintained b y the heteromodal associative cortex (dorsal convexity of the prefrontal co rtex), and the supramodal associative cortex (located rostrally in the fron tal lobes) is unable to provide reliable monitoring and assessment of simul taneous neural cognitive networks carrying insufficient and inadequate inpu t. The core deficiency in AD patients might be impaired SC equated with the disability to maintain sequential and simultaneous "attention to life". Th e Self-Consciousness Questionnaire, a clinical scale providing multidimensi onal measurement, indicates that different aspects of consciousness are not correlated with overall cognitive deficiency as determined by the MMSE.