A 7-year-old boy is being seen for a well-child checkup by his primary provider. During routine screening, his parents report that he has several hour episodes of being “wild” about once per week. They are unable to identify any particular trigger. When asked to elaborate further, his parents report that he keeps acting up until he gets their attention and ends up in a time out. He throws his toys around, hits his older sisters, and swears at his mother. His father is worried that his son has bipolar disorder, as his paternal grandmother was institutionalized with “manic depression.” Review of systems is significant for sleeping only five hours each night and then being full of energy the next day. The boy’s mental status exam is significant for irritability, labile affect, oppositionality, and distractibility. The provider tells the parents that the boy does not meet criteria for bipolar disorder. Which of the following is the most likely rationale for the provider’s decision?