Stress and anxiety

A poor diet -- for example, low levels of vitamin B12 -- can also contribute to stress or anxiety. Performance anxiety is related to specific situations, like taking a test or making a presentation in public. Posttraumatic stress disorder (PTSD) develops after a traumatic event like war, physical or sexual assault, or a natural disaster. People with generalized anxiety disorder experience almost constant worry or anxiety about many things on more than half of all days for 6 months. Panic disorder or panic attacks involve sudden and unexplained fear, rapid breathing, and increased heartbeat.

In very rare cases, a tumor of the adrenal gland (pheochromocytoma) may be the cause of anxiety. The symptoms are caused by an overproduction of hormones responsible for the feelings of anxiety.