Diagnostic overshadowing: A cause of overlooked depression in prisoners

Depression is a pervasive and prevalent mental health disorder among prisoners, yet it frequently remains undiagnosed due to the phenomenon of diagnostic overshadowing - a clinical bias where prominent conditions or contexts obscure less obvious mental health issues. This review explores diagnostic overshadowing as a key barrier to identifying depression in people in custody, focusing on diagnostic failures, their consequences, and solutions. We review global literature on depression prevalence, which affects prisoners at significantly higher rates than the general population, yet it is frequently misdiagnosed or goes unrecognized due to overshadowing by the more prominent features of substance use, challenging behaviours or the prison context itself. Failure to recognize readily treatable depressive disorders because of diagnostic overshadowing results in serious but avoidable consequences, including elevated suicide rates, increased recidivism, and other adverse outcomes such as substance abuse and institutional violence, which collectively and individually perpetuate the cycle of personal distress and dysfunction, as well as the human and associated costs to others in society. By describing and highlighting diagnostic overshadowing as a particular problem in correctional settings, and by exploring its mechanisms in correctional psychiatry settings, we advocate for solutions for more reliable recognition of depression in prisoners, which is an essential first step to effectively address this readily treatable but easily overlooked serious mental disorder.