the shifting marijuana legal environment
TRANSCRIPT
The Shifting Marijuana Legal Environment: Linking
Epidemiology and Neuroscience
Wilson M. Compton, MD, MPE
Deputy Director
1 to 2 Days23%
3 to 5 Days16%
6 to 19 Days19%
20 or More Days41%
Among Current Marijuana Users, Two In Five Are Daily or Almost Daily Users
Source: SAMHSA, 2013 National Survey on Drug Use and Health (September 2014).
19.8 Million Past Month Users of Marijuana in 2013
Number of Days Used Marijuana in the Past Month
Increasing Potency of Marijuana (% Δ-9 THC)
SOURCE: University of Mississippi Marijuana Project
%
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
0
2
4
6
8
10
12
14
16
∆-9 THC
Addiction: About 9% of users may become dependent
(~1 in 6 who start in adolescence, and 25-50% of daily users)32
15
9
17
118
5
23
05
101520253035
Percent
* Nonmedical Use Source: Anthony JC et al., 1994
Estimated Prevalence of Dependence Among Users
**
Similarly, 8.9% estimated lifetime DSM-IV Dependence among marijuana users (NESARC data collected 2001-2005, Lopez-Quintero et
al., 2011)
75
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77
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79
80
81
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95
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97
98
99
0 1 2 3 4 5 6 7 8 9 10
11
12
13
14
0
20
40
60
80
100
Past Year Use
Perceived Risk is Correlated with Use of Marijuana:
12th Graders’ Use vs. Perceived Risk of Occasional MJ Use
SOURCE: University of Michigan, 2014 Monitoring the Future Study
Denotes significant difference between 2013 and 2014.
%
Source of Marijuana* among 12th Graders in 2012 and 2013, by State
Policy
Given friend
B
ought friend
B
ought dealer/s
tranger
G
iven relativ
e
O
ther method
B
ought relativ
e
T
ook relativ
e
T
ook friend
O
wn MMJ Rx
Someone else's MMJ Rx0
20
40
60
80
100Medical Marijuana States Non-Medical Marijuana States
**
**
*Categories not mutually exclusive ** Statistically significant difference SOURCE: University of Michigan, 2013 Monitoring the Future Study
%
Methods of Using Marijuana Among
12th Grade Past Year Users, 2014
Smoking In Food In Drink Other0.0
20.0
40.0
60.0
80.0
100.0
Non-MMJ States MMJ States
SOURCE: University of Michigan, 2014 Monitoring the Future Study
Non-usersused 1 Dx
used 2 Dx
used 3 Dx
-8
-6
-4
-2
0
2
Avera
ge P
oin
t D
iffere
nce
in
IQ
sco
re
(IQ
at
ag
e 3
8 –
IQ
at
ag
e 1
3)
Persistent Marijuana Users Show A Significant IQ Drop between
Childhood and Midlife
Source: Meier MH et al., PNAS Early Edition 2012
Followed 1,037 individuals from birth to age 38. Tested marijuana use at 18, 21, 26, 32 and 38. Tested for IQ at ages 13 and 38
Silins, et al., Lancet Psychiatry 2014;1:286-293
HS Complete0
0.2
0.4
0.6
0.8
1
1.2
Never< MonthlyMonthly +Weekly +Daily
HS Complete0
0.2
0.4
0.6
0.8
1
1.2
O.R.
Cannabis Depend
0
5
10
15
20O.R.
Other Illicit Drug
0
2
4
6
8
O.R.
Suicide At-tempt
012345678
O.R.
More Teenage Use of Cannabis Associated with Worse Outcomes in
20’s (3 Australia/New Zealand Studies)
Cannabis May be Causally Associated with Schizophrenia
Giordano, Ohlsson, Sundquist, Sundquist, Kendler Psychological Medicine 2015
Baseline After 1 Yr After 5 Yrs After 7 Yrs
General Pop'n 10.44 9.19 5.95 4.24
Relative Pairs:
1st Cousin 9.40 8.37 5.85 4.05
Paternal 1/2 Sib 9.15 8.42 6.12 4.18
Maternal 1/2 Sib 6.00 5.85 3.42 2.58
Full Sibs 5.07 4.47 2.80 1.98
MZ Twins* 3.92 3.38 2.63 1.67
* Extrapolated
Risk (Odds Ratios) of hospital diagnosis of schizophrenia after prior registration for cannabis abuse in: (i) general population and (ii) co-relatives, allowing time
from exposure to disease to vary by 1-7 years
Schizophrenia Risk May Cause Cannabis Use
Power, Verweij, Zuhair, Montgomery, Henders, Heath, Madden, Medland, Wray, Martin. Molecular Psych 2014
Mean standardized schizophrenia polygenic risk scores for twin pairs of with neither (n=272), one (n=273) or both twins (n=445) reporting cannabis use.
P = 0.001 (Ordinal Regression)
Subcortical structures evaluated for group differences between daily marijuana users
and nonusers.
Weiland B J et al. J. Neurosci. 2015;35:1505-1512
Complexity in Long-Term MJ (n=48) v. Controls (n=62)
Filbey et al. PNAS Nov 10, 2014
MJ users had significantly less bilateral orbitofrontal gyri volume
Trend suggests FA of the forceps minor
tract initially increased then
decreased
Higher functional and structural OFC connectivity
Adolescent Brain Cognitive DevelopmentNational Longitudinal Study
NIDA, NIAAA, NCI, NICHD, NIMHD, ORWH, NIMH, NINDS, OBSSR
Ten year longitudinal study of 10,000 children from
age 10 to 20 years to assess effects of drugs on
individual brain development trajectories
Marijuana as Medicine?
•Promise lies in purified ingredients or synthetic compounds with more selectivity, less adverse effects
•Applications: pain, nausea, wasting, obesity, muscle spasticity, addiction, inflammatory conditions, HIVNIH research (across NIDA, NCI, NINDS,
NIAID, etc.) focuses on THC, CBD, and compounds that alter the function of the
endocannabinoid system.