Can 1-3 dimethylamylamine cause some type of brain damage or neurological problems?

Yes. The FDA has : issued warnings because of reports of illnesses & deaths associated with use of DMAA & continues its efforts to get it off the market. Methylhexanamine constricts blood vessels, which raises blood pressure & pulse, leading to heart attacks & strokes. There is no proof of its efficacy as a dietary supplement. World-wide professional sports associations test athletes for it as a banned substance.