Alzheimers disease (AD) has lately been suggested to be a systemic disorder, not confined only to the brain. An increasing volume of evidence indicates that AD is also associated with peripheral vascular changes that might be important markers in tests of given pathophysiological hypotheses.
Researchers from the Faculty of Medicine, University of Szeged, Hungary, hypothesized that the onset of AD affects cholinergic microcirculatory patterns, and set out to compare the levels of spontaneous forehead and forearm flow motion in different age groups and to establish whether aging influences the rhythmic oscillation of the microvasculature. AD-specific alterations were also sought.
A total of 99 individuals were enrolled in the study. Oscillations in laser Doppler signals derived from the forehead and forearm skin were analyzed in 77 healthy probands from 4 various age groups (ranging between 15 and 77 years) and 22 late-onset sporadic AD patients.
A characteristic pattern of oscillations in the microcirculatory blood flux was observed in the forehead skin, the occurrence of which correlated inversely with age. The occurrence of forehead vasomotion pattern was 100% in the teenagers, whereas it was significantly less in the elderly control subjects (32%) and in the AD patients (18%).
Forearm reactive hyperemia was provoked by 1-min occlusion of the brachial artery, and the vascular reactivity was calculated. This phenomenon also proved to be age-dependent, but the process was not related to AD. Results indicate that the lack of forehead vasomotion reflects aging better than does the forearm vasomotion. Both of these functions are preserved in AD.
The novel findings from this study, which appears in the journal Microvascular Research (available online 14 October 2005) are that the forehead flow motion displays an age-dependent pattern. Also, under resting conditions, low-frequency oscillation in the forearm microcirculation was found in one-third of the subjects examined and no age-dependence was observed and occlusion of the brachial artery provokes flow motion in young, but not in elderly subjects. In addition, results indicate that the level of vascular reactivity decreases with aging, and there is no characteristic difference in the different flow motion patterns examined for AD patients.
Data from this study indicate that the oscillations in the microcirculation exhibit an age-dependent pattern, which is more pronounced in the forehead than in the forearm. These results furnish additional information characterizing the aging of the skin.