BACKGROUND
Machine learning (ML) systems are parts of Artificial Intelligence (AI) that automatically learn models from data in order to make better decisions. Natural Language Processing (NLP), by using corpora and learning approaches, provides good performance in statistical tasks, such as text classification or sentiment mining.
OBJECTIVE
The primary aim of this systematic review is to summarize and characterize studies that used ML and NLP techniques for mental health, in methodological and technical terms. The secondary aim is to consider the interest of these methods in the mental health clinical practice.
METHODS
This systematic review follows the PRISMA guidelines and is registered on PROSPERO. The research was conducted on 4 medical databases (Pubmed, Scopus, ScienceDirect and PsycINFO) with the following keywords: machine learning, data mining, psychiatry, mental health, mental disorder. The exclusion criteria are: languages other than English, anonymization process, case studies, conference papers and reviews. No limitations on publication dates were imposed.
RESULTS
327 articles were identified, 269 were excluded, and 58 were included in the review. Results were organized through a qualitative perspective. Even though studies had heterogeneous topics and methods, some themes emerged. Population studies could be grouped into three categories: patients included in medical databases, patients who came to the emergency room, and social-media users. The main objectives were symptom extraction, severity of illness classification, comparison of therapy effectiveness, psychopathological clues, and nosography challenging. Data from electronic medical records and that from social media were the two major data sources. With regard to the methods used, preprocessing used the standard methods of NLP and unique identifier extraction dedicated to medical texts. Efficient classifiers were preferred rather than "transparent” functioning classifiers. Python was the most frequently used platform.
CONCLUSIONS
ML and NLP models have been highly topical issues in medicine in recent years and may be considered a new paradigm in medical research. However, these processes tend to confirm clinical hypotheses rather than developing entirely new knowledge,. and one major category of the population, social-media users, is obviously an imprecise cohort. In addition, some language-specific features can improve the performance of NLP methods, and their extension to other languages should be more closely investigated. However, ML and NLP techniques provide useful information from unexplored data (i.e., patient’s daily habits that are usually inaccessible to care providers). This may be considered to be an additional tool at every step of mental health care: diagnosis, prognosis, treatment efficacy and monitoring. Therefore, ethical issues – like predicting psychiatric troubles or involvement in the physician-patient relationship – remain and should be discussed in a timely manner. ML and NLP methods may offer multiple perspectives in mental health research but should also be considered as tools to support clinical practice.
CLINICALTRIAL
Number CRD42019107376
Machine learning and natural language processing in mental health: a systematic review