Objective: Semantic memory is the result of progressive development during childhood. During the construction of the lexico-semantic network, the features of the objects are progressively stored to build our knowledge. Alzheimer’s disease (AD) disrupts conceptual links that support semantic memory. Individuals suffering from AD lose access to words as well as to meaning. Some researchers have made the assumption that cognitive retrogenesis leads to a cognitive decline that reverses acquisition steps in childhood. This study proposes to analyze the validity of this theory applied to semantic knowledge. Method: We administered a semantic knowledge questionnaire (SKQ) featuring 30 objects associated with 4 questions (2 superordinate questions; Q1 = general; Q2 = intracategorial; and 2 subordinate questions; Q3 = perceptual; Q4 = thematical/functional) to 93 children (30 5-year-old children; 30 7-year-old children; and 33 9-year-old children), 32 healthy elderly people, and 66 AD patients (20 in the initial stage of the disease, AD1; 16 in the intermediate stage, AD2; and 30 in the advanced stage, AD3). Results: Our results show that the total number of errors in the SKQ evolved in a “u-shaped” curve: children made less and less errors at the SKQ during development while AD patients presented the reverse pattern. Moreover, the performance of 5-year-old children was identical to that of AD3 patients. Similar results were observed with 7-year-old children and AD2 patients, and with 9-year-old children and AD1 patients. Conclusion: These data are consistent with the idea of a lexico-semantic retrogenesis process.