Anxiety is associated with a wide range of physical illnesses, medication side effects, and other psychiatric disorders.
Increased heart rate, sweating, shaking, nausea, dizziness, feeling of suffocation/trouble breathing, etc.
Some of the problem associated with mental problems are the eating disorders,mood disorders and anxiety disorders.
Anxiety disorders and mood disorders aren't the same. Mood disorders include all affective disorders including anxiety disorders.
Diazepam and other anxiolytics reduce the frequency, severity, and duration of anxiety symptoms in individuals who have medical or psychiatric disorders associated with anxiety.
Phobias can be diagnosed as a disorder themselves, but disorders such as Panic Disorder, Generalized Anxiety Disorder, and PTSD are all often associated with phobias.
There are many good books and sites available on anxiety disorders. One good book on the subject of anxiety disorders is The Anxiety Book by Jonathon Davidson.
Substance abuse disorders are not associated with low IQ.
It has been proposed that in patients with anxiety or mood disorders there are alterations in the functions of central neurotransmitters, including GABA, serotonin and noradrenaline. Research in this area suggests that the primary dysfunction in anxiety disorders is a down-regulation of the brain inhibitory GABA and serotonin systems and an up-regulation of the brain pro-anxiety noradrenaline system, or some degree of involvement from each
People with debilitating anxiety are said to be suffering from anxiety disorders, such as phobias, panic disorders, and generalized anxiety disorder.
Sometimes this behavior is associated with anxiety-based disorders, but there is no specific disease or disorder that has this as a symptom.
Anna Melissa Crawford has written: 'Familial factors associated with the treatment outcome and severity of childhood anxiety disorders' -- subject(s): Anxiety in children, Anxiety, Behavior therapy, Cognitive therapy
You can read about anxiety disorders online or at healthy magazines at your local convince store or deli or DR store. You can also ask others who have been through the trouble of anxiety disorders.
Simple phobia/specific phobia, social phobia and agoraphobia are indeed all anxiety disorders.