What is the difference between normal anxiety and pathological anxiety?

          An individual experiences anxiety daily throughout his or her life; therefore, anxiety is a rather normal emotions, which evolved to enable one to respond accordingly to danger. Anxiety is an unpleasant emotion, which has characteristics of physiological arousal, dread, and a general sense of danger (Hansell & Damour, 2008). Whereas, pathological anxiety occurs in a context, which is not appropriate and as for the continuum between mild and extreme anxiety, this type of anxiety is overly intense. The main differences between normal anxiety and pathological anxiety are the duration, intensity, and frequency of anxiety. Normal anxiety is beneficial and remains beneficial until its duration, intensity, and frequency become to great it interferes with one's functioning; then it is considered pathological anxiety. Therefore, normal anxiety serves the purpose of improving one's well-being and functioning. Whereas, pathological anxiety interferes with one's well-being and impairs one's functioning, therefore it causes distress. Pathological anxiety is not beneficial and the results of this type of anxiety can lead to one suffering from a certain type of anxiety disorders.    

Reference

Hansell, J., & Damour, L. (2008). Abnormal psychology (2nd ed.). Hoboken, NJ: Wiley.