BOSTON (AP) -- The more hits to the head an amateur football player takes, the greater the risk that he will be depressed, have difficulty making decisions or develop other forms of cognitive impairment as an adult, a preliminary study suggests.The study by Boston University researchers published in the Journal of Neurotrauma on Thursday is the first of its kind to look at the connection between the cumulative number of impacts sustained from youth football through college and later-in-life mental difficulties, according to Dr. Robert Stern, one of the co-authors.Stern, of the BU School of Medicine, said the study is \an important first step\ to guide future research, but cautioned that it should not be used to influence parenting or policy decisions.\This is not meant to be: 'If you get hit a certain number of times