It is estimated that 3-14% of older people have anxiety disorders. These can be very difficult to treat. Anxiety disorders usually start in very early life and if not treated correctly, these problems can persist and become chronic. In the elderly they can go unrecognised and sometimes they are attributed to the process of aging. Often anxiety presents itself along with other disorders, like depression for instance.
In the elderly pharmacological treatments seem to be more more cost-effective than psychological treatments, the latest being more useful for young adults. If the initial treatment does not work in the elderly there's no research available about the effectiveness what to do next, and doctors have to rely on their previous experiences.
Dr Andres Fonseca discusses in his article for The Mental Elf "Lost in anxiety: treatment-resistant anxiety in older people" the problems with psychological therapies in the elderly and what to do in this population if the first strategy used fails to help the person recover.