# Can Semantics Uncover Hidden Relations between Neurodegenerative Diseases and Artistic Behaviors?
## 4 State-of-the-Art
### Ontologies Related to NDs
The hierarchical structure of the ADO serves as a strong navigation tree for terminology integration and text-mining applications. [PERSON] et al. [94] constructed the ADO, which contains information focused on the main biological components of AD such as preclinical, clinical, etiological, molecular, and cellular mechanisms. The ontology was enriched by adding synonyms and references, and it was validated with impressive results in real-life scenarios. The ADO has the capability to reveal both established and scattered knowledge in scientific text, and it supports semantic searches. The ontology was built following the ontology-building life cycle and adheres to the criteria of top-level ontologies. Knowledge was acquired from various sources, including review articles, online books, standard knowledge bases, encyclopedias, glossaries, and informative websites. The important feature of the ontologies is that knowledge can be acquired through web-based searches, and the NCBO [71] services were used to retrieve synonym information for automatic and manual mapping to external ontologies. [PERSON] et al. [98] published the CADRO as part of a comparative analysis by the National Institute on Aging. It has three categorization systems: clinical, translational, and basic. Although ADO provides valuable insights into the mechanisms of AD, it does not fully encompass the biological domain of the disease. Another study will be conducted to investigate the representation of fuzzy features of knowledge related to AD. [PERSON] et al. created AD Map Ontology (ADMO) [99] to improve the depiction of AD pathophysiology by integrating the AlzPathway in a consistent ontology. [PERSON] et al. [100] proposed the Alzheimer's Disease Integrated Ontology (ADIO), which integrates two biomedical ontologies related to AD: ADO and the ADMO. ADO covers the clinical, preclinical, experimental, and molecular mechanisms of the disease, whereas ADMO represents the complex pathophysiology of AD. LogMap [101], a matching and alignment system for ontologies that is used to find correspondences between concepts from different ontologies, was used to align the overlapping modules of the integrated ontologies. The use of Ontograf, a Protege [19] plugin, allowed the authors to visualize the classes graph. On the other hand, [PERSON] et al. [102] introduced the Bio Portal, a repository of over 300 biomedical ontologies that were developed in various formats, including OBO format, Rich Release Format (RFF), OWL, and more. The repository [71] contains 190 million triples, including 9.8 million cross-ontology mappings of diverse types that were generated both manually and automatically, along with their own metadata. The quality of these ontologies was assessed using metrics, peer reviews, and categorization into different domains. All of the stored data can be accessed via REST APIs and a SPARQL endpoint, and mappings between terms in different ontologies are also available. Each ontology in BioPortal is assigned a stable identifier and is indexed with version numbers. The services of BioPortal Web [71] include retrieving ontology metadata, ontology content, downloading an ontology, and searching ontologies. Users can request ontology material based on the ontology identifier, in which case the most recent version of the ontology is returned, or by specifying a particular version number. The search service allows for searching the entire repository or a selected group of ontologies, with options for exact or approximate matching and searching in concept names and synonyms or property values [103]. The ontologies identified by our systematic review are summarized in Table 1 under specific criteria. The domain for which the ontology is developed and the encoded language are presented. Fuzzy logic compatibility is also mentioned. Finally, the availability of every ontology and its status are also included in the criteria.