Safety function

As the brain is designed to ensure survival it has developed four incredible ways to do so:

• Helping an athlete predict possible outcomes – this is good for boosting their dopamine (our reward chemical that is thought to be lower in those with ADHD) but can also cause worries in those who over-predict and ruminate about the negatives.
• Body budgeting so the athlete’s body works efficiently – this can be tricky in athlete’s with the hyperactive type of ADHD or who hyperfocus meaning they work too intensely on a sporting problem and put their body budget out of whack.
• Prioritizing negative memories – this is to keep the athlete remembering the things that could harm them so they can stay safe. Helpful for physical safety – unhelpful for high performance. Neuroscientists now believe that for every negative thought you have about yourself, you require five positive things to stay in a good place. 
• Activating a threat system in emergencies to help us escape anything that could harm us. Originally designed for physical threats but now often over-activated for psychological or physiological threats too. 

All these together aim to keep an athlete as comfortable as possible and ensure their survival. When they combine they push the athlete towards their comfort zone (for safety) which can prevent them  stretching themselves or try new things, limiting their ability to perform at a high level. The really important area for you to understand as a coach is the threat system.