In Alzheimer's disease, the typical clinical symptoms and the pathological findings are restricted to the nervous system. Nevertheless, like in some other neurologic-metabolic disorders, several alterations are found in peripheral tissues. The aim of this study was to examine whether cellular properties which can be studied in vitro on skin fibroblast cultures obtained from Alzheimer's disease patients differ from those of age-matched controls. Down syndrome patients were also included, since the same neuropathological findings are present in nearly 100% of Down syndrome patients. Since Alzheimer's disease is an age-related disorder, we examined the growth characteristics of skin fibroblast cultures. The in vitro senescence of cultured fibroblasts is widely accepted as a model for in vivo ageing. Normal growth properties were found. We can conclude that there is no premature ageing in Alzheimer's disease nor in Down syndrome and that the abnormalities found in peripheral tissues are related to the disease itself. The beta amyloid precursor protein (beta APP) has been shown to have adhesive interactions. We therefore investigated several parameters of adhesion in the skin fibroblast cultures: adhesion to a fibronectin coat, adhesion to extracellular matrix of Alzheimer's disease cultures and semi-quantification of adhesion-related molecules (beta 1-integrin, cell surface proteoglycans, extracellular matrix proteoglycans, extracellular matrix fibronectin). No significant difference was found in the parameters examined.