“…Dr. Roberta J. Pentney, a former researcher at the State University of New York at Buffalo, found that alcohol disrupts brain function in adults by damaging message-carrying dendrites on neurons in the cerebellum, a structure involved in learning and motor coordination. This reduces communication between neurons, alters their structure and causes some of the impairment associated with intoxication. It does not kill off entire cells, however.”

The damage to dendrites is not permanent… “According to researchers such as Roberta J. Pentney, professor of anatomy and cell biology at the University at Buffalo, this damage is mostly reversible.” (http://health.howstuffworks.com/10-brain-myths.htm) So I wouldn't worry too much about the dendrites either unless you're an alcoholic.