Research indicates that people with generalized anxiety disorder can, indeed, develop a major depressive disorder.
Allow me to outline generalized anxiety disorder:
Excessive anxiety and worry about a number of events.
Difficulty controlling this anxiety
Restlessness, easily fatigued, difficulty concentrating, irritability, muscle tension and sleep disturbance
Symptoms of major depressive disorder include:
markedly decreased interest in almost all activities
significant weight gain or loss, sleeping too much or too little
notable agitation or slowing
loss of energy
feelings of worthlessness
decreased ability to concentrate or make decisions
preoccupying thoughts about death
The co-existence of both disorders (referred to as “comorbid”) can be a significant impairment in even daily functioning. Rather than intellectually shopping for a single diagnosis, accept that there may be multiple concurrent diagnoses.
These symptoms are not difficult to detect, and the disorders are not difficult to diagnose. If they are not addressed, the course and rate of recovery from a physical illness will be significantly prolonged.