Final answer:
The shift from ADD to ADHD is significant because it recognizes that some individuals with ADHD may not exhibit hyperactivity. This shift in terminology provides a more accurate understanding of the disorder.
Step-by-step explanation:
ADHD, which stands for Attention Deficit Hyperactivity Disorder, is a neurodevelopmental disorder that affects both children and adults. The shift from ADD (Attention Deficit Disorder) to ADHD is significant because it acknowledges that some individuals with ADHD may not exhibit hyperactivity as their primary symptom. ADD was used to describe individuals who mainly struggled with inattention, while ADHD encompasses both inattention and hyperactivity or impulsivity. This shift in terminology helps to provide a more accurate and comprehensive understanding of the disorder and allows for better diagnosis and treatment.