Brain atrophy prevention agent comprising a phospholipid as an active ingredient is disclosed. The phospholipid contains a highly unsaturated fatty acid as a constituent fatty acid.L'invention concerne un agent de prévention d'atrophie cérébrale comprenant un phospholipide en tant que principe actif. Le phospholipide contient un acide gras hautement insaturé en tant qu'acide gras constituant.