Deep learning (DL) approaches to natural language processing (NLP) offer powerful tools for creating digital twins (DTs) of patients in psychiatry and neurological rehabilitation by processing unstructured textual data such as clinical notes, therapy transcripts, and patient-reported outcomes. Techniques such as transformer models (e.g., BERT, GPT) enable the analysis of nuanced language patterns to assess mental health, cognitive impairment, and emotional states. These models can capture subtle linguistic features that correlate with symptoms of degenerative disorders (e.g., aMCI) and mental disorders such as depression or anxiety, providing valuable insights for personalized treatment. In neurological rehabilitation, NLP models help track progress by analyzing a patient’s language during therapy, such as recovery from aphasia or cognitive decline caused by neurological deficits. DL methods integrate multimodal data by combining NLP with speech, gesture, and sensor data to create holistic DTs that simulate patient behavior and health trajectories. Recurrent neural networks (RNNs) and attention mechanisms are commonly used to analyze time-series conversational data, enabling long-term tracking of a patient’s mental health. These approaches support predictive analytics and early diagnosis by predicting potential relapses or adverse events by identifying patterns in patient communication over time. However, it is important to note that ethical considerations such as ensuring data privacy, avoiding bias, and ensuring explainability are crucial when implementing NLP models in clinical settings to ensure patient trust and safety. NLP-based DTs can facilitate collaborative care by summarizing patient insights and providing actionable recommendations to medical staff in real time. By leveraging DL, these DTs offer scalable, data-driven solutions to promote personalized care and improve outcomes in psychiatry and neurological rehabilitation. Keywords: artificial intelligence; deep learning; mental health; neurologic deficit; natural language processing; psychiatry; neurorehabilitation