Yes, it is possible to be addicted to weed...

                                  Cognitive Function as an Emerging Treatment
                                                    for Marijuana Addiction

Chronic use of marijuana leads to dose related cognitive impairments of the working memory, attention, verbal learning and memory functions. These impairments are not fully reversible even after cessation and may be predictive of poor treatment response. Current behavioral therapies used for marijuana addiction treatment have shown only modest abstinence rates, and no effective pharmaceutical treatments are available. Behavioral therapies are successful dependent on the patient’s ability to pay attention, understand behavioral change strategies and how to implement them. Intact cognitive functioning could be vital to more complex CBT therapies that focus on cognitive retraining and learning of new behavioral skills.
Therefore, targeting cognitive impairment associated with chronic marijuana use is proposed as a possible new strategy of marijuana addiction treatment.

Preclinical non-human studies suggest that the cholinergic system may have an important role in the cognitive impairment induced by marijuana.  Cannabinoid agonist THC inhibits cholinergic transmission in the brain and reduction of Acetylcholine (Ach) release has been significantly correlated with the impairment of working memory. Other preclinical non-human studies suggest that cognitive enhancing medications such as physostigstigmine, tetrahydroaminoacridne, donepezil, and galantamine could prove useful in reducing drug use. Physostigmine was shown to reverse the THC induced reduction of correct choices and increase in errors in the eight arm radial maze task in rats. Additionally, tetrahydroaminoacridne reversed the THC induced release of Ach in the dorsal hippocampus. These cholinesterase inhibitors increase synaptic Ach levels which could increase inhibitory control vital since reduced inhibitory control is a key antecedent to addictive behaviors. These cognitive enhancing medications could also alleviate cannabis induced spatial and working memory deficits, and be especially effective in improving attentional function which could increase the success of treatment outcome.

This summary of pharmacological and behavioral therapies targeting cognitive functioning in marijuana users indicates a need for future research in several areas. The aforementioned cognitive enhancing medications have not yet been studied in humans, and controlled human studies must be performed. Clinical studies that use validated cognitive tests with good psychometric properties sensitive to pharmacological and behavioral interventions are needed to measure cognitive function and the effects of drug use. Further studies designed to determine which cognitive functions are most predictive of treatment outcomes must be conducted. Additionally the extent to which improvements in cognitive function can be evaluated by functional imaging techniques needs to be explored.   Finally, optimal timing of treatment initiation is of great importance. Therefore the efficacy of initiating treatment after a period of abstinence versus beginning treatment while still using marijuana with the intention to facilitate abstinence should also be evaluated.

References: Sofuoglu, M., Sugarman, D. E., & Carroll, K. M. (2010). Cognitive function as an emerging treatment target for marijuana addiction. Experimental and Clinical Psychopharmacology, 18(2), 109-119. doi:10.1037/