"neurosis" is an antiquated term.
Anxiety Disorder (formerly anxiety neurosis) is a diagnosis made by a physician when a patient exhibits certain specific symptoms and other causes for the symptoms have been ruled out.
The DSM-IV lists the symptoms required for a diagnosis of Generalized Anxiety Disorder to be:
A. Excessive anxiety and worry (apprehensive expectation), occurring more days than not, for at least 6 months, about a number of events or activities (such as work or school performance).
B. The person finds it difficult to control the worry.
C. The anxiety and worry are associated with three (or more) of the following six symptoms (with at least some symptoms present for more days than not, for the past 6 months). Note: Only one item is required in children.
D. The focus of the anxiety and worry is not confined to features of an Axis I disorder, eg, the anxiety or worry is not about having a panic attack (as in Panic Disorder), being embarrassed in public (as in social phobia), being contaminated (as in obsessive-compulsive disorder), being away from home or close relatives (as in separation anxiety disorder), gaining weight (as in anorexia nervosa), having multiple physical complaints (as in somatization disorder), or having a serious illness (as in hypochondriasis), and the anxiety and worry do not occur exclusively during post-traumatic stress disorder.
E. The anxiety, worry or physical symptoms cause clinically significant distress or impairment in social, occupational or other important areas of functioning.
F. The disturbance is not due to the direct physiological effects of a substance (eg, a drug of abuse, a medication) or a general medical condition (eg, hyperthyroidism) and does not occur exclusively during a mood disorder, a psychotic disorder, or a Pervasive Developmental Disorder.