In the Doctor's Opinion chapter of the big book of Alcoholics Anonymous. There are three elements of addiction described.
1.) An allergy of the body
2.) A mental obsession
3.) A spiritual malady
Science may now offer proof of the "allergy of the body".
Recent research by European scientist's Drew Kiraly, Scott Russo and Rebecca Hofford theorize that,
"Recent evidence suggests a role for dysregulated immune signaling in the pathophysiology of multiple psychiatric diseases. While there is evidence that immune responses in the periphery and the central nervous system are altered by exposure to drugs of abuse, the contributions of neuroimmune interactions to addictive behaviors."
While the claim may seem confusing or advanced in literary nature, one could break it down quite simply by thinking of "allergy" and "evidence of immune responses from exposure to drugs of abuse (including alcohol.)
For a deeper dive make sure to read more here.
Sources: https://www.webofscience.com/wos/woscc/full-record/WOS:000486177300048