Study register · detailQuerschnitts-Kohortenstudie · Adolescence & Development · 1999
Specific attentional dysfunction in adults following early start of cannabis use.
Ehrenreich et al.·PsychopharmacologyImpact 2.8
Clear benefitGRADELow391 citations
Samplen = 148 Pat.
ControlLate-onset users and healthy non-users
EndpointReaction time
Blindingn.a.
DesignQuerschnitts-Kohortenstudie
”Key finding
Early onset of cannabis use (before the 16th year of life) is associated with specific, persistent impairments in visual scanning reaction time in adulthood.
Summary
Cross-sectional study (n=99 pure cannabis users + n=49 controls, selected from 250 users). Early onset of use (<16 years; n=48) led to significantly prolonged reaction times in visual scanning vs. late-onset users (>16 years; n=51) and controls (p<0.05). Other attention functions (alertness, divided attention, flexibility, working memory) not impaired. The only predictor was age of onset, not total dose or THC levels. Finding supports persistent neurocognitive vulnerability due to peripubertal cannabis use.
P
PopulationAdults, regular cannabis users (n=99, of which 48 early-onset users <16 years, 51 late-onset users ≥16 years) as well as healthy controls (n=49), free of other drug abuse or neuropsychiatric disorders
I
InterventionRegular cannabis use with onset before vs. after the 16th year of life (naturalistic exposure)
C
ControlLate-onset users (onset ≥16 years) and healthy non-users (n=49)
O
OutcomeEarly-onset users showed significantly prolonged reaction times in visual scanning vs. controls and late-onset users; no differences in other attention functions; early onset was the only significant predictor
Confidence in the evidence
Very lowLowModerateHigh
Low
The second of four GRADE levels, the effect estimate is of limited reliability.
<h4>Rationale and objective</h4>The present study tested the hypothesis that chronic interference by cannabis with endogenous cannabinoid systems during peripubertal development causes specific and persistent brain alterations in humans. As an index of cannabinoid action, visual scanning, along with other attentional functions, was chosen. Visual scanning undergoes a major maturation process around age 12-15 years and, in addition, the visual system is known to react specifically and sensitively to cannabinoids.<h4>Methods</h4>From 250 individuals consuming cannabis regularly, 99 healthy pure cannabis users were selected. They were free of any other past or present drug abuse, or history of neuropsychiatric disease. After an interview, physical examination, analysis of routine laboratory parameters, plasma/urine analyses for drugs, and MMPI testing, users and respective controls were subjected to a computer-assisted attention test battery comprising visual scanning, alertness, divided attention, flexibility, and working memory.<h4>Results</h4>Of the potential predictors of test performance within the user group, including present age, age of onset of cannabis use, degree of acute intoxication (THC+THCOH plasma levels), and cumulative toxicity (estimated total life dose), an early age of onset turned out to be the only predictor, predicting impaired reaction times exclusively in visual scanning. Early-onset users (onset before age 16; n = 48) showed a significant impairment in reaction times in this function, whereas late-onset users (onset after age 16; n = 51) did not differ from controls (n = 49).<h4>Conclusions</h4>These data suggest that beginning cannabis use during early adolescence may lead to enduring effects on specific attentional functions in adulthood. Apparently, vulnerable periods during brain development exist that are subject to persistent alterations by interfering exogenous cannabinoids.