Why is it so hard for some people to concentrate?

Partial answers follow:

Productive Reading - Insights Into Attentional Control - Neurology:

- Remarkable Medicine book (Dreyfus)
- How To (Temporarily) Cure Hyperactivity book (about Inattentive ADHD relief) (Wild)
- The Hyperactive Child book (Renshaw)
- Nerves in Collision book (Alvarez)

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https://twitter.com/CharlesThomasW7/status/1291778394015899648

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- Medicines which work for some with ADHD
- Medicines which work for some with epilepsy
- Medicines which work for some with narcolepsy
- Nootropics which work for some

https://cthomaswildadhd.blogspot.com/