1. "Anti-depressant" is not synonymous with "SSRI". Benzodiazepines are also used to treat depression and can create a strong chemical dependency.
2. The concept of addiction is hard to define, and is becoming more so. Some drugs (marijuana springs to mind) can be considered addictive, but don't seem to cause the unthinking crave-gratify-repeat cycle you see with cocaine or nicotine. Some have argued that checking email or Facebook, playing MMORPGs, and "consuming" pornography are addictive.
2. The concept of addiction is hard to define, and is becoming more so. Some drugs (marijuana springs to mind) can be considered addictive, but don't seem to cause the unthinking crave-gratify-repeat cycle you see with cocaine or nicotine. Some have argued that checking email or Facebook, playing MMORPGs, and "consuming" pornography are addictive.