Friday, 24 May 2013

Comorbidity and costs

Another for the "underlying variables very likely cause both substance abuse AND negative outcomes" file, via +Ole Rogeberg . It appears that novelty-seeking and conduct disorder strongly predict future alcohol, tobacco, and other drug use among youths.

They suggest that early identification of those likely to be at risk and subsequent management of conduct disorders and of novelty-seeking behaviour might reduce the risk of substance abuse.

Behavioral or pharmacological treatment of disruptive disorders in children and adolescents is likely to have lasting effects across multiple disruptive psychopathologies due to the common thread that underlies ADHD, CD [Conduct Disorder], and NS [Novelty Seeking] — the inability to plan out actions, inhibit actions, and consider the implications of actions (impulsivity) (Miller, Stephen, & Tudway, 2004). For instance, preliminary findings from our lab recently determined that higher levels of CD and ADHD symptoms are associated with higher levels of initial sensitivity (e.g., subjective and autonomic experiences, such as reports of pleasure, liking the taste, nausea, heart rate) to alcohol and tobacco during adolescence, which suggests that these individuals may be primed to be more responsive to substances of abuse (Bidwell et al., 2012; Palmer et al., 2012; Wills et al., 1994).
Think back to how social cost studies tend to attribute the costs of substance abuse. They begin by defining as counterfactual the average outcomes for all individuals of similar age and gender; the monetised difference in outcomes between average non-abusers and substance-abusers is taken as social cost.

But those likely to become heavy substance-abusers would not have had average outcomes had drugs, alcohol, or tobacco never existed.

The relevant counterfactual group are those who were at similar risk of becoming substance abusers and who managed to avoid it. And even that will lead to overestimates because the general-purpose technology that lets those lucky individuals avoid substance temptations would itself drive outcomes.

It's entirely likely that substance abuse aggravates things for those with disruptive psychopathologies and that the costs they impose on others are consequently higher than they would have been. But substance abuse is only responsible for part of that cost - not for the whole she-bang.

It's also worth pointing out that this new study tilts the scales further in favour of Ole Rogeberg in his argument with the Dunedin folks about cohort selection effects. I still wish that Dunedin could be convinced to put up a GSS-style front end for their data so that other researchers could check results while not compromising privacy.

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