Despondence is The Darkness, and those who suffer from it are called "The Bleak," for all forms of nihilism are theirs: depression, fatalism, pessimism, morbidity, suicide. They have been exposed to the Darkness, aka Negative Energy, and so are overwhelmed with negative emotions and self-destructive desires. Treatment for the Bleak is remarkably easy: get them outside into the radiance of the Life-Sun, or relegate them to brightly lit rooms with many windows. In extreme cases, Priests of the Light can channel Positive Energy into these afflicted, curing them of their melancholy.
... temporarily. Because you can never truly defeat the darkness with light, nor light with darkness; one defines the other. While an infusion of positive energy is great for cheering someone up, if they are truly, deeply, chronically depressive, then all the priest has done is turn a depressive into a manic-depressive. Many Cultists of the Dark are Bleak, which is why a fair amount of them turn to necromancy and consort with the undead. The only treatment they are likely to receive is a swift death at the hands of a Paladin of the Light.
Insistence, the Air Disorder, is better known as "The Dragon's Way," referencing the way in which dragons become increasingly set in their ways as they age: obsessively counting their hoards, ritualistically turning widdershins thrice before lying down, speaking in sentences of precisely eighteen syllables, repeating a menial yet complex task (such as treasure-polishing) until it is done "properly", etc. In addition to obsessive-compulsive disorders, the Dragon-touched are also subject to excessively consumptive behavior such as eating until one vomits (and then eating again), hoarding, kleptomania, and other forms of greed and gluttony. It is important to note that these behaviors are not motivated by evil intent ("I will steal from others because I want to deprive them") or even by conscious desire ("It is valuable and therefore I must own it"); instead it is a far more visceral and urgent compulsion of "I must do this, therefore I will do this!"
Common belief is that these actions spring not from fear or desire, but from flights of whimsy which, when left unchecked, grow like a spring thunderstorm: first they are little breezes, but soon they become roaring tornadoes which wander randomly and consume everything in their path. Treatment for the Dragon-Touched involves ritual bathing and immersion in Elemental Water, in the belief that as water always seeks to run away, it will wash away the Air which has become stuck and stale within the afflicted.