Depression and Thought Intrusions, Relating Thought Frequency to Activation and Arousal

Laboratory studies have demonstrated that task-unrelated image and thought (TUIT) likelihood decreased with increased age, displayed a circadian rhythm, and increased with hyperactivity; these outcomes are consistent with the speculation that TUIT production is directly related to brain activation/arousal level. We examined the association between TUIT likelihood and depression and anxiety and their putative activation/arousal levels. Individuals diagnosed with a major depressive disorder reported TUITs while performing a vigilance task. Significant, p < .05, correlations indicated that deeper depression, dejection, and perceived fatigue were associated with a reduced likelihood of unintentional TUITs and greater anxiety were associated with increased likelihood of unintentional TUITs. These results were consistent with an association between arousal/activation and unbidden TUIT likelihood.