Restlessness in Generalized Anxiety Disorder: Using Actigraphy to Measure Physiological Reactions to Threat

Generalized anxiety disorder (GAD) is characterized by excessive, uncontrollable worry accompanied by symptoms of physiological arousal. Although individuals with GAD report greater subjective arousal than healthy individuals, they show equivalent or even attenuated physiological reactions to threat. This may result from using physiological measures better suited to fear than anxiety. To test this possibility, 102 adults with and without GAD were assessed for restlessness, a core physiological symptom of GAD. They were exposed to an in vivo threat task designed to elicit anxiety in the laboratory. Throughout the task, restlessness was measured physiologically with actigraphy sensors on both ankles and both wrists, and subjectively with self-report ratings. The GAD group reported higher subjective restlessness than the no-GAD group, and in the subset of cases who had restlessness as a clinically significant symptom, actigraphy scores were reliably elevated as well. However, although actigraphy scores increased with proximity to the threat, the increases did not differ by group. These findings provide initial validation for actigraphy as a novel measure of motor restlessness in GAD. In addition, they underscore the value of measuring restlessness using multiple assessment methods. These methods suggest that, in GAD, restlessness reflects a chronic state of arousal rather than a heightened physiological reaction to threat.