PURPOSE: A phosphonic acid ester is provided to treat a brain functional disorder and an age-related memory disorder. CONSTITUTION: The present invention relates to the use of phosphonic acid esters for the treatment and prevention of functional disorders of the brain and depression. In the chemical formula I, R is a straight chain or a branched chain alkyl being substituted to more than one halogen atom, R1 is a straight chain or a branched alkyl containing hydrogen or under 6 carbon atoms, R2 is a hydrogen or a straight chain or a branched chain alkyl, alkylcarbonyl, alkoxycarbonyl, or alkylsulphonyl having under 6 carbon atoms in the alkyl, R3 is under 6 straight chain or branched chain alkyl, and X is oxygen or sulfur.
USE OF PHOSPHONIC ACID ESTERS FOR THE TREATMENT OF FUNCTIONAL DISORDERS OF THE BRAIN AND DEPRESSION