In short, the answer is yes. A Johns Hopkins study on the Dose-related neurocognitive effects of marijuana use found the following results:
As joints smoked per week increased, performance decreased on tests measuring memory, executive functioning, psychomotor speed, and manual dexterity. When dividing the group into light, middle, and heavy user groups, the heavy group performed significantly below the light group on 5 of 35 measures and the size of theeffect ranged from 3.00 to 4.20 SD units. Duration of use had little effect on neurocognitive performance. 1