The nervous and psychosocial system of humans is not static; rather, it is continuously influenced by development. This developmental process is not a smooth progression; each life phase differs from the previous and the subsequent ones. Depending on the life phase and the achieved developmental age, the expressions of life, the strategies for coping with life, and ultimately the psychopathology of the individual take shape.

In the first section, the themes of life in the various developmental phases are presented along with their risks, opportunities, and crises. The second section illustrates how the symptoms of certain disorders manifest and how they differ across the various life phases. The psychiatric disorders and reactions, as well as their development-specific manifestations, are highlighted in summary. In the concluding section, psychiatric treatment methods are presented, demonstrating that developmental age significantly influences therapeutic approaches, including both medication and psychotherapy.