D4HEALTH is a web platform dedicated to diagnosing and monitoring mental disorders. The system evaluates the user by collecting information from a digital diary. It analyses temporal progress of emotional negativity obtaining an overall score of the predisposition to suffer from a mental disorder. This platform is developed with the aim of supporting specialists (psychologist or psychiatrist) to carry out a continuous and more personalized follow-up of the users / patients, reporting an analysis of the trend while dangerousness alarms are generated in the case of negative events. On the other hand, the application has a massive analysis system of data text. This data text is used to monitor the emotional influence that a particular topic causes in a large group of users. Therefore, it is possible to study temporal trends in the population as well as the global discontent that a situation can trigger. The system has artificial intelligence algorithms trained on databases extracted from Twitter. First, the emotional negativity analysis model was trained on tweets collected in a public database based on natural language processing techniques. Secondly, the model of diagnosis of mental disorders was trained through public Twitter users who were previously studied by specialists concluding their depressive tendency. Finally, the implemented models were integrated into a web application that allows the analysis of Twitter profiles.