Subjective experience of thought overactivation in mood disorders: beyond racing and crowded thoughts

Racing thoughts, crowded thoughts and flight of ideas are frequent symptoms in mood disorders, but the underlying subjective experience of overactivation of thought processes remains poorly documented.

Qualitative analysis of audiotaped interviews explored subjective experience of thought overactivation in patients with mood disorders (sample 1, n = 45). Quantitative analysis considered the properties of a newly developed rating scale in sample 1, in an additional sample of patients with mood disorders (sample 2, n = 37) and in healthy subjects (sample 3, n = 38).

Qualitative analysis of individual interviews revealed that 5 conceptual categories characterized thought overactivation: sequential thought flow, overstimulation, competition for resource allocation, unexpected/unexplained onset, and association with mood and emotions. A principal component analysis of the initial 16-item rating scale indicated that a single component explained 55.9% of the variance, with major and exclusive contributions from 9 items, which were retained in the final 9-item Subjective Thought Overactivation Questionnaire (STOQ; Cronbach's α = 0.95). Total score correlated significantly with activation, depression and perceived conflict subscales of the Internal State Scale (ISS; rs = 0.57-0.66, p < 0.001). It was associated with decreased well-being (ISS; rs = -0.48, p = 0.001) and increased state anxiety (State-Trait Anxiety Inventory; rs = 0.60, p < 0.001). The STOQ score was significantly higher in patients than in healthy subjects. It allowed distinguishing between ISS mood states, with the highest median score in mixed states.

Sample size, representativeness, possible bias in qualitative analysis, and quality of expert consensus.

Qualitative analysis of clinical interviews, together with a new short rating scale, contributed to a documentation of subjective thought overactivation, an important but often undetected feature in mood disorders.