Attention and memory in the preclinical stage of dementia.

The aim of this study was to investigate whether attention may be specifically impaired in Alzheimer's disease from the early stages of the disease. Subgroups of patients with different types of mild cognitive impairment were selected according to standard criteria. Patients and controls were given tasks exploring various subcomponents of attention and executive functions. Only subgroups of mild cognitive impairment characterized by memory disorders obtained lower scores than controls on attention and executive tasks. On the basis of the scores obtained on the Clinical Dementia Rating at the 1-year follow-up, patients were redistributed into 2 groups: those who developed and those who did not develop dementia. Patients who presented evolution to dementia already had, at baseline, lower scores than patients who did not evolve on tasks exploring attention and executive functions. The results suggest that not only memory disorders but also attention/executive deficits may characterize dementia at the onset.

Responsiveness to cholinesterase inhibitors in Alzheimer's disease: a possible role for the 192 Q/R polymorphism of the PON-1 gene.

Cholinesterase inhibitors (ChEIs) are the most established treatment strategy in Alzheimer's disease (AD). However, the responsiveness to these drugs is widely heterogeneous and the majority of AD subjects do not respond to treatment. Paraoxonase-1 (PON-1) is a potent endogenous ChEI and has been widely studied for its ability to hydrolyze environmental neurotoxins. Serum levels and biological activity of PON-1 display wide inter-individual variability and are strongly influenced by a common polymorphism at position 192 of the PON-1 gene. Here, we evaluated whether this gene variation is associated with differences in the ability of AD subjects to respond to therapy with ChEIs. We found that individuals that respond to ChEIs had a significantly higher frequency of the R allele, compared to non-responders (P<0.05). This study indicates that the 192 Q/R polymorphism of the PON-1 gene might influence responsiveness to ChEIs, with potentially important implications for the treatment of AD. Mutations of genes encoding for endogenous modulators of the cholinergic system should merit further investigation as prognostic indicators of individual response to treatment in AD subjects.

Reaction and movement times in individuals with chronic traumatic brain injury with good motor recovery.

Reaction times and movement times were studied in 18 individuals with severe traumatic brain injury (TBI) and 36 matched normal controls. Reaction times depended on the type of task: in the case of simple visual stimuli (Alertness condition) they were similar in individuals with TBI and normal controls. In contrast, individuals with TBI were slower in a Go-no-go test. Regardless of task, movement times depended on movement length and were slower in individuals with TBI. These findings indicate the presence of a residual motor programming deficit in individuals with TBI even in the chronic stage and in the presence of good motor recovery, as assessed clinically.