Tuore väitöskirja paljastaa, että krooninen kannabiksen käyttö aiheuttaa vakavia aivotoiminnan häiriöitä

Tuoreen väitöskirjatutkimuksen mukaan kroonisilla kannabiksen käyttäjillä on vakavia puutteita kognitiivisen ja emotionaalisen prosessoinnin alueella – krooninen kannabiksen käyttö aiheuttaa aivotoiminnan vakavia häiriöitä

Wesley, Michael J.: Wake Forest U., US
Dissertation Abstracts International: Section B: The Sciences and Engineering. Vol.72(4-B),2011, pp. 1951

Marijuana is the most frequently used illegal drug in the country with medicinal and recreational use increasing.

The present series of studies was designed to examine functional brain activity associated with altered decision-making and affective or emotional processing in long-term chronic marijuana users (MJ Users).

The first aim was to determine how activity in MJ Users is altered during different components of the decision-making process.

As MJ Users performed poorly on the Iowa Gambling Task (IGT), they had greater activity during selection and decreased activity in response to feedback, compared to non-marijuana using controls (Controls), suggesting that MJ Users are more engaged while implementing choices but functionally insensitive to the consequences of those choices during decision-making.

To understand how functional insensitivity to feedback related to the development of problem solving strategies, a series of analyses were conducted during the earliest phase of the IGT.

MJ Users were found to have decreased functional responses to aversive feedback, and they lacked activity in the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC) that predicted learning in Controls.
These data demonstrated that insensitivity to aversive feedback was directly related to the inability of MJ Users to develop successful performance and suggest that MJ Users have failed integration of aversive feedback information into executive functioning processes.

A final series of analyses were conducted to determine if affective processing was altered in MJ Users for stimuli considered to be emotional. MJ Users and Controls judged the same stimuli as emotional; however, MJ Users exhibited decreased functional responses in the mPFC and ACC while viewing emotional stimuli.

Response magnitudes for positive were significantly less in MJ Users in several brain areas and hypoactive in the mPFC and ACC, suggesting a more cognitive, rather than emotional, functional response to affective stimuli.

Taken together, these studies are important because they identify a potentially serious side effect of long-term marijuana use.

They show that MJ Users have decreased functional responses in brain areas crucial for cognitive and emotional processing and suggest that long term marijuana use leads to compromised decision-making abilities and experience of emotions.