In this work, the set of genes associated with mental diseases such as dementia was examined and analyzed using previously developed gene ontology annotation tools and databases. The aim of the study is to describe the gene ontologies and molecular mechanisms of dementia based on the analysis of the related human gene set using available bioinformatics databases, annotation and recent publications. Dementia is a chronic, general, usually irreversible decrease in cognitive function that affects all aspects of cognitive activity. The enriched gene ontology categories for dementia genes are regulation of neuronal death and cell death, cellular components organization, and cognition. A high connectivity of genes and their products was discovered when studying the structure of the gene network.