The "dominance" behavior of high T levels is generally positive imo, but it's a different story when natural levels are significantly exceeded for many years or decades as is increasingly common. It would be wise to keep this in mind and protect your brain like you would your liver or heart.
Long term use of supra-physiologic doses of AAS have been clearly shown to induce changes in the brain (thinning of the pre-frontal cortex for instance), that are associated with emotional blunting, cognitive rigidity, uncertainty intolerance, and impaired reverse learning.
In other words, a loss of intellectual flexibility and impaired problem solving similar to what's seen in neurodegeneration in the elderly, an inability to adapt to new information, and manifests itself as hostility in ambiguous situations or changed circumstances. (if you pay close attention, you can see that behavior among some long term users here).
So for example, when rodents learn to follow a path, turn left (vs right) and push a button with their nose to receive a food treat are given high dose AAS long enough to cause thinning of the prefrontal cortex, when the reward supplying button is changed to the right, their non-AAS exposed counterparts quickly figure it out, but they don't, remaining stuck in the same pattern for a long time and become increasingly aggressive.
Most of the damage is related to oxidation and inflammation from androgen receptors being overdriven. A lot of compounds can help reduce this oxidative stress. GLPs seem very effective.
"“Pre‑frontal cortex is associated with numerous cognitive functions, such as self‑regulation, mental flexibility, attention and inhibition… dependent AAS users had significantly thinner cortex in pre‑frontal regions"
"Testosterone-induced oxidative stress in brain tissue has been associated with impaired memory and neuroinflammation."
Prolonged high-dose AAS use is associated with poorer cognitive function across multiple domains, and the observed regional associations between cortical brain morphometry and memory and working memory performance may suggest differential brain-based mechanisms. The public, health care...
pubmed.ncbi.nlm.nih.gov
There are hundreds of studies from the 80's up to now all pointing in a similar direction to this.