1. Fish
Especially predatory types of fish.
Fish contain organic mercury which binds to fat ( like fat in fish). Sine the brain is of a lot of fat, organic mercury accumulates there by bypasing the blood brain barrier, where it does its damage.
Tuna (187 mcg/kg), snapper (256 mcg/kg )and butter fish (677 mcg/kg) have one of the highest concentrations.
It's better to take an algea based dha supplement, that was testes for heavy metals.
2. Alcohol
Pretty obvious, we drank it. Stimulates the production of GABA which inhibits nerv cell function. It also inhibits vitamin B1, causing sugar to be fermented instead of breathed having a carcinogenic effect on the brain.
3. Fried/Roasted/Grilled Foods
Meats and roasted nuts. Process produces AGE's ( advanced glycation endproducts )
Well known for disrupting all sorts of neurological functions, leading for example to sleep problems. In addition trans fats are an end product of this process.
4. Artifical sweeteners
Like Asphatan, which you can find in light soda, sugar free sodas etc.
Can inhibit the synthesis of neurotransmitters like dopamine, serotonin.
If you want something sweet, take oat syrup, date syrup, maple syrup etc.