Subjective perception of cost (and benefit), of course, also varies individually, and the perception of “rock-bottom”, if any, ranges from a life-threatening health problem to a mere understanding that one's volitional control of behavior has degraded. Feynman (1985), the Nobel prize-winning physicist, describes how he quit drinking upon getting frightened about experiencing “strong feeling that you have to have a drink” (p. 204). Similar aversive effects may be produced by an experience of the short-term memory lapse resulting from cannabis use, or by observation of personal/social degradation concomitant to drug use, when sufficient value is attached to the memory capacity or to the health or social status. Age- (and chronic drug use-) related changes may include the gradual lowering of the general hedonic effect and craving. These are testable hypotheses with potential practical implications. The common fitness metric/etiologic mechanisms may determine similarity between the patterns of development of habitual consummatory behaviors, their persistence, fluctuations and discontinuation, parallelisms between them, and comorbidities of their extreme forms (let alone comorbidities of substance-specific addictions) comprising spectra of disorders.
