67.4% of my patients have an addiction to porn. OK, I made up the precise statistic to get your attention; I just meant a significant subgroup! Pornography activates the novelty-seeking pathways in the brain and by some accounts, is indistinguishable from cocaine in its activation of the pathways of the brain involved in the regulation of dopamine. ADDers love to have dopamine surges and, "Voila!" you have a volatile combination! 

The problem comes when the person becomes compulsive and hyper-focused on the behavior, which then replaces healthy interpersonal relations and other life affirming strategies with compulsive viewing, searching, and masturbating to the material. The widespread availability of pornography has propelled it as drug/behavior of choice. 

My technique for helping patients bothered by this addiction is to UNCOUPLE the shame, guilt, and secretiveness of the behavior and to address the anxiety, depression, and impulsivity which makes them vulnerable. Some of the pharmacological agents used for other addictions that have dopaminergic properties have also been helpful. It is also important to keep reasonable expectations. Don't expect the behavior to go away just because you started your treatment for ADHD. It will take time and patience.