it is challenging to provide an exact number of how many people live with ADHD worldwide because the prevalence rates can vary based on different factors such as diagnostic criteria, geographical location, and study methodologies.
However, according to the Centers for Disease Control and Prevention (CDC) in the United States, the estimated prevalence of ADHD among children aged 2-17 years was around 9.4% in 2016. For adults, the estimated prevalence of ADHD in the United States was approximately 4.4% based on data from the National Survey on Drug Use and Health (NSDUH) for 2019.
When looking at global estimates, a meta-analysis published in the journal "Neuroscience & Biobehavioral Reviews" in 2017 reported a pooled worldwide prevalence rate of ADHD in children and adolescents to be approximately 7.2%. For adults, the prevalence rate was estimated to be around 2.8%.
It's important to note that these figures are based on available data up until 2021, and the numbers may have changed as more research and awareness about ADHD continue to grow.
If you are interested in more up-to-date statistics on ADHD prevalence, I recommend consulting recent reports and studies from reputable organizations like the World Health Organization (WHO) or national health agencies that conduct research on mental health and developmental disorders.