We explored the neural substrate of anosognosia for cognitive impairment in Alzheimer's disease (AD). Two hundred nine patients with mild to moderate dementia and their caregivers assessed patients' cognitive impairment by answering a structured questionnaire. Subjects rated 13 cognitive domains as not impaired or associated with mild, moderate, severe, or very severe difficulties, and a sum score was calculated. Two measures of anosognosia were derived. A patient's self assessment, unconfounded by objective measurements of cognitive deficits such as dementia severity and episodic memory impairment, provided an estimate of impaired self-evaluative judgment about cognition in AD. Impaired self-evaluation was related to a decrease in brain metabolism measured with 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in orbital prefrontal cortex and in medial temporal structures. In a cognitive model of anosognosia, medial temporal dysfunction might impair a comparison mechanism between current information on cognition and personal knowledge. Hypoactivity in orbitofrontal cortex may not allow AD patients to update the qualitative judgment associated with their impaired cognitive abilities. Caregivers perceived greater cognitive impairments than patients did. The discrepancy score between caregiver's and patient's evaluations, an other measure of anosognosia, was negatively related to metabolic activity located in the temporoparietal junction, consistent with an impairment of self-referential processes and perspective taking in AD.

The interpretation of the data regarding cognitive outcome in children who have suffered from mild traumatic brain injury (MTBI) remains currently controversial. The aim of the present study is to explore attentional and executive functioning in 6-12-year-old children who experienced a MTBI. A total of 15 children with MTBI and 15 matched noninjured children participated in the study. Attentional tasks using the Test for Attentional Performance battery were administered one year after the injury. In comparison to the noninjury children, MTBI children performed less accurately on selective attentional and updating tasks. These preliminary findings support the view that MTBI can have an impact on specific attentional functioning in children one year postinjury.

This study describes the neuropsychological assessment of 34 patients with questionable Alzheimer's disease (QAD) followed up for 3 years. Several measures were selected from the California Verbal Learning Test (CVLT) and compared to other cognitive tasks to assess the best neuropsychological indices for (a) detecting early memory impairment in QAD and (b) predicting conversion to AD. Concerning detection, the results indicated that a recall measure depending on semantic categorization (short-delay cued recall) signaled a memory deficit in stable QAD patients, suggesting that episodic and semantic memory problems are involved in the early cognitive impairments of stable QAD patients. However, the conversion to AD was best predicted by the initial performance at the recency index (score reflecting high reliance on working memory), corroborating the idea that AD patients (even at the questionable stage) essentially rely on preserved phonological loop functioning in memory tasks. Finally, an additional impairment in visuospatial memory (Rey's figure) provided a good discriminant value to distinguish converters from stable QAD patients, showing that various cognitive disabilities deteriorate in AD.

Different scales can be used to evaluate dementia severity in Alzheimer's disease (AD). They do assess different cognitive or functional abilities, but their global scores are frequently in mutual correlation. Functional imaging provides an objective method for the staging of dementia severity. Positron emission tomography was used to assess the relationship between brain metabolism and four dementia scales that reflect a patient's global cognitive abilities (mini mental state), caregiver's evaluation of cognitive impairment (newly designed scale), daily living functioning (instrumental activities of daily living) and global dementia (clinical dementia rating). We wondered whether different clinical dementia scales would be related to severity of metabolic impairment in the same brain regions, and might reflect impairment of common cognitive processes. 225 patients with probable AD were recruited in a prospective multicentre European study. All clinical scales were related to brain metabolism in associative temporal, parietal or frontal areas. A factorial analysis demonstrated that all scales could be classified in a single factor. That factor was highly correlated to decrease of cerebral activity in bilateral parietal and temporal cortices, precuneus, and left middle frontal gyrus. This finding suggests that global scores for all scales provided similar information on the neural substrate of dementia severity. Capitalizing on the neuroimaging literature, dementia severity reflected by reduced metabolism in posterior and frontal associative areas in AD might be related to a decrease of controlled processes.

Traumatic brain injury is a major cause of mortality and morbidity in children younger than 15 years of age. To evaluate the role of subcortical lesions on neurodevelopmental outcomes, long-term outcomes of 50 children with severe traumatic brain injury before 4 years of age (accidental injury, n = 21, nonaccidental injury, n = 29) were reviewed retrospectively and compared with late magnetic resonance imaging (MRI) findings: no visible lesions, cortical lesions, or subcortical lesions. Subcortical lesions occurred in both accidental and nonaccidental traumatic brain injuries. Traumatic brain injury severity (initial Glasgow Coma Scale or coma duration) was significantly associated with subcortical lesions. Long-term motor or visual deficiencies occurred in one third of patients and cognitive deficiencies in 52.1%. Although deficiencies occurred without visible MRI lesions, global outcome scores, motor delay, visual impairment, head growth slowing, global intellectual quotients, and planning performances were significantly worse in patients with subcortical lesions. An alarming deterioration in intellectual quotient over time was noted. It was concluded that neurodevelopmental outcomes are worrisome after severe traumatic brain injury in young children, and subcortical lesions affect the prognosis.

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We describe six psychomotor, language, and neuropsychological sequential developmental evaluations in a boy who sustained a severe bifrontal traumatic brain injury (TBI) at 19 months of age. Visuospatial, drawing, and writing skills failed to develop normally. Gradually increasing difficulties were noted in language leading to reading and spontaneous speech difficulties. The last two evaluations showed executive deficits in inhibition, flexibility, and working memory. Those executive abnormalities seemed to be involved in the other impairments. In conclusion, early frontal brain injury disorganizes the development of cognitive functions, and interactions exist between executive function and other cognitive functions during development.

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