Two-month stability of hyperbolic discount rates for delayed monetary gains in abstinent inpatient alcoholics

Alcohol dependence has been associated with disrupted neuroendocrine systems, impulsivity in intertemporal choice (delay discounting). However, little is known regarding stability of discount rates in alcoholics. This study examined both differential stability (stability of individual differences) and absolute stability (stability of group mean) of hyperbolic discount rates for monetary gains in severe alcoholic inpatients (diagnosed with DSM-IV) over a 2-month period during abstinence.

We estimated male alcoholics' discount rates for delayed monetary rewards on the basis of their pattern of choices between smaller immediate rewards (1,100-8,000 yen) and larger, delayed rewards (2,500-8,500 yen; at delays from 1 week to 6 months), two times at 2-month time-interval during hospitalized alcohol withdrawal.

It was observed that the alcoholics' mean hyperbolic discount rates for gains had both differential and absolute stability over 2 months, although a slight non-significant decrease in the group mean of the discount rates was observed.

The results indicate that abstinent alcoholic's discount rates are stable over a relatively long-term period. The usefulness of assessing discount rates of addicts in psychoneuroendocrinology and neuroeconomics of addiction is discussed.