I have previously stated our brain is hedonistically conservative and allows only so much pleasurable stimulation. It adjusts to the dopamine surges by producing less dopamine. This is tolerance. Tolerance is a need to consume more of the chemical to overcome neurotransmitter status quo. It is taking larger doses to get high and using a substance over longer periods of time. To have the same euphoric stimulation it takes more of the release of dopamine. Over time, a biological need for the chemical is implanted in the brain and body. This is dependency (physiological). If the substance is suddenly stopped there are painful physiological withdrawal symptoms. Dependency is hard living that collaterally interferes with work, school, relationships, and healthy leisure. The ramifications from continued use will increase mind-body stress, anxiety, depression and cause physical damage —> the same conditions the addict wanted the chemicals to alleviate. Over time, drug toxicity will set in and it will affect thinking, emotions, and behaviors. With time the overactivity, hyperactivity, and the increased amount of drugs and alcohol have neuro-rotting degenerative effects (i. e. a fried brain). An overused enervated brain can only take so much damage. Invariably, the repercussions from increased chemical usage has the addict on an imploding free-fall, beat-down, and life-threatening path that sets the stage and eventually opens the gate to the premature death-nail.