^A The technical term is “economic good”⁹ because one buys “goods and services,” but that would lead to the unfortunate sentence “Drugs are, in fact, an economic good.…”

^B This view, that psychiatric categorizations (drug dependence, schizophrenia, depression, etc.) are actually categories of symptoms rather than reflections of an underlying disease, is related to the concept of endophenotypes. The term “endophenotype” comes from the idea that different genes can have the same effects (phenotypes), but the concept here goes beyond simple statements of genetic variation. The concept is closer to that of hypothetical constructs or trans-disease processes.⁶⁹ Hypothetical constructs are intervening variables that allow one to look for underlying concepts in neural activity (such as subjective value,⁷⁰ which we discussed in Chapter 3), while trans-disease processes are treatable vulnerabilities that produce different dysfunctions in different contexts (such as impulsivity,⁷¹ Chapter 5).

It is true that psychiatric categories have become reliable over the past decades such that they can be consistently applied—multiple psychiatrists will generally assign the same people to the same categories. However, successful treatment has lagged behind. Unfortunately, category reliability does not necessarily imply a unified mechanistic validity.⁷² There is a current movement afoot called computational psychiatry that attempts to redefine psychiatric illnesses in terms of their underlying mechanisms, connecting psychiatric symptoms with underlying dysfunction based on computational models of decision-making. We will return to this concept in Chapter 21.

^C As noted in the preface, treatment needs to be tailored to the individual. Thus, one should check with one’s own medical professionals before embarking on any treatment regimen.

^D Some addicts die before getting a chance to age out and others never stop their addiction.