Smoking’s reputation just went from bad to worse. A new study found that smoking speeds up the decline of mental functioning in middle-aged men. A 50-year-old male smoker would see the same rate of deterioration as a man 10 years older who never smoked, according to researchers. This was true even after taking into account the educational level and health of the study’s participants. Social smokers—those who light up occasionally—weren’t immune to the effect, either. “Intermittent smokers showed the same cognitive decline as persistent smokers, showing the importance of definitive smoking cessation,” the lead researcher, Séverine Sabia, Ph.D., told CNN. Even recent quitters weren’t immune. In fact, men who had quit smoking recently showed even greater declines in “executive function,” a measure of short-term memory, and the ability to organize, plan and pay attention. Female smokers, who were also included in the study, had no increased mental decline when compared to female non-smokers. Researchers think this may be an indication of different smoking and health patterns in women. The study included around 6,000 male and 2,100 female British civil servants. On average, the volunteers were 56 years old at their first visit. Researchers assessed their mental functioning three times over a 10-year period, and questioned the participants about their current and past smoking habits. The upside of the study is that men who had stopped smoking for at least 10 years showed the same level of mental decline as non-smokers. If you are still smoking, it’s not too late to quit before you start to forget where you keep your cigarettes.