title: A methodology for the characterization and diagnosis of cognitive impairments-Application to specific language impairment.
abstract: OBJECTIVE
  The diagnosis of mental disorders is in most cases very difficult because of the high heterogeneity and overlap between associated cognitive impairments. Furthermore, early and individualized diagnosis is crucial. In this paper, we propose a methodology to support the individualized characterization and diagnosis of cognitive impairments. The methodology can also be used as a test platform for existing theories on the causes of the impairments. We use computational cognitive modeling to gather information on the cognitive mechanisms underlying normal and impaired behavior. We then use this information to feed machine-learning algorithms to individually characterize the impairment and to differentiate between normal and impaired behavior. We apply the methodology to the particular case of specific language impairment (SLI) in Spanish-speaking children.
  
  
  METHODS
  The proposed methodology begins by defining a task in which normal and individuals with impairment present behavioral differences. Next we build a computational cognitive model of that task and individualize it: we build a cognitive model for each participant and optimize its parameter values to fit the behavior of each participant. Finally, we use the optimized parameter values to feed different machine learning algorithms. The methodology was applied to an existing database of 48 Spanish-speaking children (24 normal and 24 SLI children) using clustering techniques for the characterization, and different classifier techniques for the diagnosis.
  
  
  RESULTS
  The characterization results show three well-differentiated groups that can be associated with the three main theories on SLI. Using a leave-one-subject-out testing methodology, all the classifiers except the DT produced sensitivity, specificity and area under curve values above 90%, reaching 100% in some cases.
  
  
  CONCLUSIONS
  The results show that our methodology is able to find relevant information on the underlying cognitive mechanisms and to use it appropriately to provide better diagnosis than existing techniques. It is also worth noting that the individualized characterization obtained using our methodology could be extremely helpful in designing individualized therapies. Moreover, the proposed methodology could be easily extended to other languages and even to other cognitive impairments not necessarily related to language.
authors.affiliation: Bioengineering Group, Spanish National Research Council (CSIC), Carretera de Campo Real, km. 0,200, La Poveda, Arganda del Rey, CP: 28500 Madrid, Spain. Electronic address: jesus.oliva@csic.es.
authors.forename: Jesús
authors.initials: J
authors.lastname: Oliva
authors.affiliation: Bioengineering Group, Spanish National Research Council (CSIC), Carretera de Campo Real, km. 0,200, La Poveda, Arganda del Rey, CP: 28500 Madrid, Spain.
authors.forename: J Ignacio
authors.initials: JI
authors.lastname: Serrano
authors.affiliation: Bioengineering Group, Spanish National Research Council (CSIC), Carretera de Campo Real, km. 0,200, La Poveda, Arganda del Rey, CP: 28500 Madrid, Spain.
authors.forename: M Dolores
authors.initials: MD
authors.lastname: del Castillo
authors.affiliation: Bioengineering Group, Spanish National Research Council (CSIC), Carretera de Campo Real, km. 0,200, La Poveda, Arganda del Rey, CP: 28500 Madrid, Spain.
authors.forename: Angel
authors.initials: A
authors.lastname: Iglesias
mesh_terms: D000465:Algorithms; D001185:Artificial Intelligence; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D003937:Diagnosis, Differential; D006801:Humans; D007806:Language Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D066230:Patient-Specific Modeling; D015203:Reproducibility of Results; D013030:Spain; D013223:Statistics as Topic
keywords: Automatic diagnosis; Computational cognitive modeling; Machine learning; Specific language impairment