The alphabetical list of personality types ends with the fourth category, named Type D for distressed. Individuals in this group are likely to be anxious, lonely, and perhaps even traumatized, all of which cause their mental health to suffer. These individuals may also be vulnerable to cardiovascular disease, but for different reasons than the highly stressed and time-pressured Type A. People high in the Type D qualities of anxiety and depression have a poor prognosis when they develop ischemic heart disease, in which blood supply is cut off to the heart, producing chest pain (angina). Paradoxically enough, Type D individuals may not actually experience anxiety and depression in terms of mood state (how they feel), because they suppress their negative emotions. By trying to reign in their negative feelings, they only exacerbate their risk of cardiac disease.
As noted by University of Northern Colorado’s Michael Allen and associates (2018), the Type D personality can be thought of as involving high levels of negative affectivity (NA) combined with high levels of social inhibition (SI). Allen et al. believes that people high in the Type D personality traits are likely to show, more generally, high levels of behavioral inhibition (BI), defined as a tendency to avoid or withdraw from novel situations. BI predisposes an individual to develop anxiety-related disorders if exposed to certain environmental stressors. Military personnel high in BI, for example, are more likely to develop post-traumatic stress disorder (PTSD) than their counterparts who do not have this temperament.