‘Most’ people either do not use drugs at all or use very little. Above a certain threshold of use begins to cause problems to health, relationships and profession. By diagnosis these are not addicts but there are many of them — approximately 68 million in the US.

Roughly 23- to 25 million might qualify as addicts. The same number of people with diabetes. Only about 2.3 million are receiving treatment, only one-tenth of those who qualify as having an illness and a fraction of those who need it. The most severe are not representative of the drug using population and many of the extreme in treatment are forced there. All this shows that drug use is different from addiction. Not sure when drug use becomes addiction – but it is a different illness.

Regarding heritability estimates, addiction does compare with other health conditions. For example, heritability of alcohol addiction is roughly 55-65 percent (among males) and opiate addiction 35-50 percent (among males). This is very similar to diabetes.

Addiction produces lasting brain changes. People, places and things can produce similar brain changes as the drug. Even after long periods of time there is a remaining susceptibility to addiction. Relapse is not a weakness. It has been proven that relapse can be caused by certain triggers.

Screening and brief intervention that discusses negative health effects of substance use can produce lasting changes in behaviour. This is especially effective for people who have not reached the most extreme abusing behaviour. Other therapies have also shown to produce lasting benefits.

Few of these therapies are being applied. The US is seeking policies that will make various types of treatment more available. There’s no reason why an addicted individual cannot receive the same kind of care as someone with diabetes or another health condition. Addiction treatment is being mainstreamed into conventional medical care.