According to the World Health Organization (WHO), ADHD affects around 5% of children and 2.5% of adults worldwide. However, the prevalence of ADHD varies by region, age, and gender. Here are some key statistics from various sources:

• Approximately 6.1 million children in the United States have been diagnosed with ADHD.
• The prevalence of ADHD in children is estimated to be around 5-10% worldwide.
• Boys are more likely to be diagnosed with ADHD than girls. In the United States, the ratio of boys to girls with ADHD is 3:1.
• Only about 1% of adults over the age of 65 have been diagnosed with ADHD.
• The prevalence of ADHD among black children is slightly higher, with an estimated 16.1% being diagnosed with the condition. Approximately 9.2% of white children in the United States have been diagnosed with ADHD, while around 6.3% of Hispanic children have been diagnosed with ADHD.
• A meta-analysis of 175 research studies worldwide on ADHD prevalence in children aged 18 and under found an overall pooled estimate of 7.2% .
• Based on DSM-IV screening of 11,422 adults for ADHD in 10 countries in the Americas, Europe, and the Middle East, the estimates of worldwide adult ADHD prevalence averaged 3.4% .
• More than 366 million adults worldwide have ADHD as of 2020.

Its important to note that these statistics are estimates and may vary depending on the source and methodology used.