Basically DHA (Omega 3 has LNA, EPA and DHA) helps brain.
Flax has LNA, a small percentage is converted to DHA. Fish oil has EPA and DHA. Now a days, DHA is prepared from vegetable oils. Fish oil or DHA from vegetable oil would be best. A word of caution: Omega 3 or Omega 6 increases need of antioxidants in body so use should be within limit.
Omega 6 is LA, GLA, DGLA, ARA, AA. Egg is rich in AA, good for kids, bad for adults (creates pain in body). Most useful form is GLA, I am not sure, which one helps in ADHD.
But usually unnoticed metal toxicities, allergies and/or nutrition ('ill' or 'mal' lack of certain minerals and vitamins) are linked with hyperactivity. Along with DHA, focus should be identifying these cause and fixing them. Jup squared by Mar might indicate problem with oil (oil metabolism) in body, where DHA may help. But Moon afflicted by Ura/Sun can indicate problems in stomach, specially because Cancer is on cusp of 6th and Sat sitting there.