Drug addiction, regardless of the substance abused, causes changes in the brain that impair an individual's ability to recognize certain facial expressions and leads to other psychological damage, according to a new study from a team of Spanish researchers. The findings show that failure to seek substance abuse help may result in serious long-term neurological damage.

For the study, a professor from the University of Granada and his team of assistants gave neuropsychological evaluations to a group of nearly 200 participants. The majority of these individuals admitted to using drugs that included alcohol, marijuana, cocaine, MDMA and methamphetamine.

The researchers found that 70 percent of the drug users showed signs of neurological damage. This manifested itself in impaired working memory, fluency, mental flexibility and multitasking ability. Additionally, many of these participants were unable to recognize negative facial emotions, including fear, wrath, disgust and sadness. Far fewer non-drug users showed any of these symptoms.

The researchers said that drug rehab programs should make note of the findings and begin to search for ways to address the neurological damage that their drug-abusing patients may have.