All anxiety disorders share the symptoms of fear and
worry. Whereas fear is a response to a known threat,
worry is a feeling of apprehension, an uneasiness in
response to an unknown threat. GAD is characterized by
the core symptoms of fear and worry and decreased concentration,
disturbed sleep, irritability, muscle tension,
fatigue, and feelings of arousal. According to the DSMIV-TR,
patients with GAD experience these symptoms
more days than not for at least 6 months.