True, but most will tell you that on their first Test only cycle they felt they were sharper and could think more clearly. That was the case for me. My first cycle was Test C 400mg/week & arimidex .5mg EOD. Many things have an effect as well, such as estrogen levels. You will see people on here write about how they feel wimpy when their estrogen gets too high.
These days, even at higher doses of Testosterone, I still feel my mind functions better than when I'm off cycle.