Problems with the study:
1) Lots of benzos out there and not all are the same
2) No distinguishing btw short acting and long acting
3) Did they rule out comorbidities? I do think all psychoactive drugs could be both helpful and harmful to the brain--depending on the individual, the underlying condition, and the dosage. Not just benzos, but antidepressants, other sedatives, anti-seizure meds, anything that changes the brain structure, the number and shape of receptors etc
4) It's what you would call a preliminary study that points in a direction of further study, with a more rigorous study design.