given year and between 12–30% are affected at some point in their life. They occur about twice as often in women than they do in men, and generally begin before the age of 25. The most common are specific phobia which affects nearly 12% and social anxiety disorder which affects 10% at some point in their life. They affect those between the ages of 15 and 35 the most and become less common after the age of 55. Rates appear to be higher in the United States and Europe. Short- and long-term anxiety Anxiety can be either a short-term "state" or a long-term "trait." Whereas trait anxiety represents worrying about future events, anxiety disorders are a group of mental disorders characterized by feelings of anxiety and fears. Four ways to be anxious In his book Anxious: the modern mind in the age of anxiety Joseph LeDoux examines four experiences of anxiety through a brain-based lens: In the presence of an existing or imminent external threat, you worry about the event and its implications for your physical and/or psychological well-being. When a threat signal occurs, it signifies either that danger is present or near in space and time or that it might be coming in the future. Nonconscious threats processing by the brain activates defensive survival circuits, resulting in changes in information processing in the brain, controlled in part by increases in arousal and behavioral and physiological responses in the body that then produce signals that feed back to the brain and complement the physiological changes there, intensifying them and extending their duration. When you notice body sensations, you worry about what they might mean for your physical and/or psychological well-being. The trigger stimulus does not have to be an external stimulus but can be an internal one, as some people are particularly sensitive to body signals. Thoughts and memories may lead to you to worry about your physical and/or psychological well-being. We do not need to be presence of an external or internal stimulus to be anxious. An episodic memory of a past trauma or of a panic attack in the past is sufficient to activate the defence circuits. Thoughts and memories may result in existential dread, such as worry about leading a meaningful life or the eventuality of death. Examples are contemplations of whether one's life has been meaningful, the inevitability of death, or the difficulty of making decisions