GAINESVILLE — A Gainesville man is accused of switching his son’s drug Adderall, used to treat attention deficit hyperactivity disorder, with a substance “believed to be sugar,” according to authorities. Dennis Lane Johnson, 46, was arrested Tuesday on a charge of second-degree child cruelty by the Multi-Agency Narcotics Squad and the Hall County Sheriff’s Office. He was later released from the Hall County Jail. Johnson’s attorney, Graham McKinnon, said his client has spent a life in law enforcement and has worked for 25 years at Phillips State Prison in Buford.“These allegations are false and are brought by a vindictive ex-wife,” McKinnon said. Authorities said they believe Johnson allegedly replaced his son’s Adderall “in the capsules with another substance, believed to be sugar” between December 2014 and September 2015.“As a result of not taking his needed medicine, the child had behavioral and emotional problems in school,” MANS Lt. Scott Ware wrote in a news release.“Once this was discovered and the child began taking his prescribed medicine again, the behavioral/emotional problems ceased and he functioned appropriately in school.”