Long-term methamphetamine abuse has many negative consequences, including addiction. Addiction is a chronic, relapsing disease, characterized by compulsive drug seeking and use and accompanied by functional and molecular changes in the brain.As is the case with many drugs, tolerance to methamphetamine’s pleasurable effects develops when it is taken repeatedly.ong-term effects may include: 1  Addiction. 2  Psychosis, including: 3  paranoia. 4  hallucinations. 5  repetitive motor activity. 6  Changes in brain structure and function. 7  Deficits in thinking and motor skills. 8  Increased distractibility. 9  Memory loss. 10  Aggressive or violent behavior. 11  Mood disturbances. 12  Severe dental problems. 13  Weight loss.