The link be­tween a sper­mi­dine-rich di­et and an ex­tend­ed healthy lifes­pan has been ev­i­dent for sev­er­al years. But not on­ly that : The sub­stance al­so de­cel­er­ates the ag­ing of the brain.

With­out so-called au­tophagy, the noc­tur­nal re­cy­cling process to re­move cell dam­age, which must ei­ther be re­stored or, in the worst case, ex­cret­ed to the out­side via the in­testines, de­posits oc­cur that pro­mote de­men­tia, di­a­betes or tu­mors, for ex­am­ple. With ad­vanc­ing age, how­ev­er, this sys­tem los­es ef­fi­cien­cy. The sub­stance sper­mi­dine stim­u­lates this very process. Sper­mi­dine is a nat­u­ral­ly oc­cur­ring sub­stance and is pro­duced, for ex­am­ple, by our body’s own cells or by bac­te­ria in the in­testines. But the an­ti-ag­ing sub­stance can al­so be in­gest­ed with food : It is found above all in wheat germ, nuts and mushrooms.

We in­ves­ti­gat­ed the in­flu­ence of sper­mi­dine on age-re­lat­ed de­cline in cog­ni­tive per­for­mance. This in­cludes, for ex­am­ple, mem­o­ry but al­so pro­cess­ing speed and con­cen­tra­tion. To test the au­tophag­ic ef­fect of sper­mi­dine on cog­ni­tion, we first had to check whether the sub­stance pass­es the blood-brain bar­ri­er. To do this, we mixed sper­mi­dine in­to the food and drink­ing wa­ter of old flies and mice, re­spec­tive­ly. In this way, we were able to show that oral­ly ad­min­is­tered sper­mi­dine reach­es the brains of mice and that they per­form bet­ter in var­i­ous mem­o­ry tests in old age than mice that were not giv­en an ex­tra por­tion of sper­mi­dine. We can ex­plain this ef­fect with im­proved qual­i­ty con­trol of the mi­to­chon­dria, al­so known as pow­er plants of the cells.

In our pre­vi­ous work, we were al­ready able to show that sper­mi­dine-fed flies have bet­ter mem­o­ry in old age and that au­tophagy is nec­es­sary for this. Here, again, we show that the im­prove­ment of mi­to­chon­dr­i­al func­tion by sper­mi­dine is very like­ly an­oth­er es­sen­tial fac­tor. In an­oth­er study, we showed that sper­mi­dine pro­motes mod­i­fi­ca­tion of the pro­tein eIF5A. This pro­tein is cen­tral to the pro­duc­tion of mi­to­chon­dr­i­al pro­teins and thus im­proves the func­tion of cel­lu­lar pow­er plants.

This ob­ser­va­tion proves a con­nec­tion which we will in­ves­ti­gate fur­ther, es­pe­cial­ly since there are very few pos­si­bil­i­ties of a pos­i­tive in­flu­ence in the cog­ni­tive area.