Reactive Depression (Adjustment Disorder) is a psychiatric illness that occurs during times of high stress or mental trauma. It is characterized by abnormal reactions that are stronger than what would be expected for the type of event that occurred.
Adjustment Disorder is caused by certain life stressors that an individual may experience and their inability to cope with these stresses. In adults, the common stressors include major life changes financial stress, loss or change in employment, marital conflicts, and personal loss of a close friend or family member.
The disorder is usually acute but can occur multiple times in an individual’s life depending on the types of stressors they are exposed to and how they cope with them. Usually social, occupational, and academic abilities are affected.
The main treatment for Adjustment Disorder is psychotherapy. Cognitive Behavioural Therapy (talk therapy) can help control and manage their feelings. Family therapy, meeting therapy goals along with the family, can be useful too. Medications or anti-anxiety drugs may also be prescribed to help cope with Adjustment Disorder.
If your nephew is not receiving any of the above Talking Therapies then I would suggest a visit back to his GP. Constant texting and questions on how he is coping is likely to do more harm than good.