Dynamics of thoughts-novel candidate marker for differential-diagnosis of mental disorders?

Thoughts are traditionally classified by their cognitive contents, such as task-related versus task-unrelated or internally versus externally oriented. However, content-based distinctions often lack diagnostic specificity in psychiatric disorders, where similar thought contents may manifest across conditions such as schizophrenia and major depressive disorder. Here, we propose a complementary framework that characterizes thoughts by their dynamics, the pattern of changes in the thought contents over time-that is, their duration, speed, and temporal precision. Converging evidence in healthy individuals shows that distinct thought dimensions map onto specific neural timescales, ranging from fine-grained oscillatory phase dynamics to coarse-grained temporal windows. Extending this framework to psychopathology, schizophrenia is characterized by temporal imprecision of thought contents across shorter and longer timescales, yielding fragmented and poorly differentiated thoughts. In contrast, major depressive disorder is marked by abnormally prolonged timescales with abnormal slowness leading to rarely changing thought contents, e.g., ruminations. We propose that the timescales of thought contents and, more generally, thought dynamics may serve as a promising marker for the differential diagnosis of thought disturbances in mental disorders.