Plasma levels of amyloid beta-protein 42 are increased in women with mild cognitive impairment.

BACKGROUND: Accumulation in the brain of small aggregates of amyloid beta-protein 42 (Abeta42) is the major pathogenic event of Alzheimer disease (AD). In familial early-onset AD this event is likely the result of Abeta42 overproduction; in the most common sporadic late-onset form of the disease the mechanisms of Abeta42 accumulation are unknown. METHODS: To address this issue the authors analyzed plasma levels of Abeta42 in 88 elderly patients with amnestic mild cognitive impairment (MCI), chosen as paradigm of preclinical sporadic AD. RESULTS: The authors found a significant increase of Abeta42 plasma levels in women with MCI, in comparison to the affected men and 72 cognitively normal age-matched subjects. The levels were independent of variables in education, apolipoprotein E genotype, cholesterol, and creatinine plasma concentrations, as well as hemoglobin content. CONCLUSIONS: The elevation of Abeta42 plasma levels in women with MCI may represent a biologic explanation for the sex-dependent increased incidence of late-onset AD in women identified by epidemiologic studies.

Hemisphere asymmetry in decision making abilities. An experimental study in unilateral brain damage.

Thirty control subjects and 60 unilateral brain-damaged patients, 30 with left hemisphere (LH) damage and 30 with right hemisphere (RH) disease, underwent a disjunctive 4-choice reaction time study. Speed of reaction (as defined by the reciprocal of reaction time (RT), movement time (MT) and total response time (TRT] and accuracy of response (as represented by the sum of errors in selecting the correct response key) were investigated comparatively as a function of side of lesion and of performance on Raven's Coloured Progressive Matrices (PM47). In contrast to movement speed (1/MT), reaction speed (1/RT) as well as total response speed (1/TRT) showed a lesion effect independent of side of damage. Conversely, accuracy was differentially impaired, LH damage being associated with a significantly higher number of errors. Speed and accuracy had different relationships with the performance on the PM47 in the two hemisphere groups. Speed was affected in parallel with changes in PM47 performance both in the LH and in RH groups, whereas accuracy was altered only in LH patients. It was concluded that speed of motor reaction is affected by unilateral brain lesions irrespective of their side, whereas decision making processes, as expressed by accuracy of response, seem to be specifically impaired by LH damage.