Depression is a common mental disorder that may affect more than 380 million people worldwide, with an estimated 5.5% of the adult population in high-income countries and 5.9% of the adult population in middle- or low-income countries having experienced a major depressive episode in the past year. Moreover, in many countries, depression is one of the ten leading causes of mortality and disability in terms of disability-adjusted life years lost. Although effective prevention and treatment programs for depression exist, many people affected by or at risk for depression do not receive such programs or do not receive the most appropriate prevention and treatment programs. This paper analyzes some of the causes that may explain this lack of prevention and treatment, especially in high-income countries, ranging from misinformation, overprescription of psychotropic drugs, lack of psychologists at the different levels of mental health care, or the rise of pseudosciences. Likewise, some of the measures that can be implemented to address these causes and their difficulties will be analyzed, taking as an example the situation of these causes and measures in Spain.