Despite advice to keep the duration of treatment short benzodiazepines are often prescribed for long periods of time, particularly in older people. Many people think benzodiazepines have a negative effect on people's cognition although the evidence from the research so far is inconclusive. A study of 2,105 people over 62 in Holland looked at people's benzodiazepine usage and tested their memory, intelligence and cognitive functioning over a 9-year period. At the end of the study the researchers found that benzodiazepines had a small, but statistically significant negative effect on people's long-term cognitive functioning.
Bierman, E. J.M. ... [et al] - The effect of chronic benzodiazepine use on cognitive functioning in older persons: good, bad or indifferent ? International Journal of Geriatric Psychiatry December 2007, 22(12), 1194-1200