The ASAM definition is the one I generally consider, based on what happens if the behavior is ceased....a strong physiological response of withdrawl. Profound CNS withdrawl responses define addiciton: Vomitting, seizures, changes in blood pressure, pulse pressure, heart rate, temperature, hallucinations, rage, motility, delusions etc.

Although the ASAM includes behavioral addictions as the "positive response" neural mapping such as gambling, the results are measurable changes in reuptake of various neurotransmitters to the extent that the person destorys their relationship, finances, health, and professional life in seeking to sustain these increased neurochemical releases. Does travel fall into this category? Not according to the ASAM anyhow.

I tend to think of it more like a compulsion rather than an addiction. It is a manifestation of another psychological problem. It does not rewire neurochemical pathways in the caornucleus accumbens, anterior cingulate cortex, basal forebrain or amygdala the way substance abuse does.