Deteriorated attention and memory, slowed thinking speed, numbed emotional experience, followed by declined academic performance, incompetence at work, or unable to fully engage in an emotionally charged event, among other functioning impairments, are common but often neglected in depersonalization disorder (DPD). The current study found impairments in information processing speed, short-term memory, sustained attention or vigilance, verbal fluency, and selective attention in depersonalized patients compared to healthy controls (HC). Constructed suppression effect models in which the symptomatic factors ‘Emotional Numbing’ and ‘Numbing’ disrupted patients’ global functioning by damaging their selective attention.