An alcoholic that I know head shakes and bobs right after he has a few drinks. It seems to be getting worse.
It could be a couple of things like either delirium tremens, psychomotor retardation, or pure coincidence. Delirium tremens or (DT's) is a psycho neurological disorder most commonly seen in people that are detoxing or having withdrawal symptoms from chronic alcohol ingestion. DT's are characterized by psychological and motor disturbances like hallucinations, confusion, or involuntary aimless muscular actions. This may surface if an alcoholic goes without a drink for a day or two but his body is accustomed to daily alcohol intake.
Psychomotor retardation can be seen in alcoholics as well as in drug induced states. Alcohol affects the central nervous system, this system controls muscular movements some of which are voluntary purposeful movements but also involuntary bizarre movements. Usually this manifests itself only in the chronic alcoholic that has been consuming alcohol for years.
These actions may also be due to pure coincidence. He may have some underlying neurological disease that is undiagnosed. You notice these movements when he consumes alcohol, but they may be evident when he is not consuming alcohol.
Alcohol acts primarily on the nerve cells within the brain. Alcohol interferes with communication between nerve cells and all other cells, suppressing the activities of excitatory nerve pathways and increasing the activities of inhibitory nerve pathways.
For example, you can normally touch your finger to your nose in one smooth motion with your eyes closed; if your cerebellum were not functioning, the motion would be extremely shaky or jerky. As alcohol affects the cerebellum, muscle movements become uncoordinated.
In addition to coordinating voluntary muscle movements, the cerebellum also coordinates the fine muscle movements involved in maintaining your balance. So, as alcohol affects the cerebellum, a person loses his or her balance frequently. At this stage, this person might be described as "falling down drunk."
Alcohol is a toxin, specifically a substance known as ethanol, which is the culprit. The signs you are describing could be indicative of what is known as Alcohol Related Brain Damage, which is related to the heavy consumption of alcohol for a minimum of ten years.
Part of this condition is what is called peripheral neurpothy, or peripheral nerve damage, which results in the destruction of the nerve pathways especially at the bodies extremities. This leads to uncontrolled tremours, and in some cases in my own practice, a bobbing head. Another sign is rapidly moving eyes. DT's are usually found in extreme withdrawal, and costitute a medical emergency, and this is also called wernickes encephalopathy, which is in effect an acute reaction to alcohol in the brain. If someone has gone without a drink for a short time, they are more likely to display sweating and stomach upsets, usually what is called here in the scotland the "dryBoak" boak being scots for wretching. The fact that the symptoms you describe get worse suggests an ARBD style scenario, but it is difficult to say much more without further symptoms. I would suggest if you haven't already done so , encourage the person to get to a physician or drug treatment team for further assessment.
Hope this helps