Repeated cannabinoid exposure during perinatal, adolescent or early adult ages produces similar longlasting deficits in object recognition and reduced social interaction in rats.

There is mounting evidence that chronic cannabis use might result in lasting neurobehavioural changes, although it remains unclear whether vulnerability diminishes with age. The current study compared the effects of cannabinoid exposure at three developmental periods on subsequent measures of memory and anxiety. Male rats aged 4 days (perinatal), 30 days (adolescent) and 56 days (young adult) were injected with vehicle or incremental doses of the cannabinoid receptor agonist CP 55940, daily for 21 consecutive days (0.15, 0.20 or 0.30 mg/kg for 7 days per dose, respectively). Following a 28-day drug-free period, working memory was assessed in an object recognition task. One week later, social anxiety was assessed in a social interaction test. Two days later, generalized anxiety was assessed in an emergence test. Results revealed that CP 55940 impaired working memory and social interaction similarly at all three ages. CP 55940 had no effects in five of six emergence test measures, but a modest but significant reduction in anxiety was noted in one measure following adolescent exposure. We conclude that chronic cannabinoid exposure leads to long-term memory impairments and increased anxiety, irrespective of the age at which drug exposure occurrs.