The present invention relates to a method of cosmetic treatment for combating the effects of skin ageing and to novel cosmetic compositions which are particularly suitable for carrying it out. According to the invention, at least one agent for promoting the adhesion of the keratinocytes of the epidermal basal layer to the dermo-epidermal junction, especially to the collagen IV of said junction, such as, in particular, a divalent metal salt or complex, preferably magnesium aspartate or magnesium chloride, is used, optionally in association with a stimulant of collagen IV synthesis and/or a stimulant of collagen VII synthesis.