Barry K Logan PhD, D-ABFT Impact of Changing Marijuana Laws on Impaired Driving

Cannabis Most popular recreational drug in the US after alcohol and tobacco. #1 Drug in the DUI Drug Arrests and 6.8% of Friday and Saturday evening drivers test positive for use. Some 25 million Americans have smoked marijuana in the past year, and more than 14 million do so regularly. Possession and use illegal under federal law, but states have variable policies on enforcement and prosecution.

Cannabis and the Brain Creative Commons Cerebellum Movement Basal Ganglia Movement Cerebral Cortex Higher cognitive function Hippocampus Learning. Memory, stress Spinal cord Peripheral sensation/pain Hypothalamus Appetite Medulla Nausea/vomiting, CTZ

Cannabis and Impairment  Well known Cognitive effects include:  Concentration and sustained attention/vigilance.  Fatigue, sleepiness, lethargy, memory problems.  Reaction time  Difficulty in thinking and problem-solving.  Difficulty in registering, processing, and using information.

Cannabis and Impairment  Well Known Psychomotor Effects Include  Decreased motor coordination  Slurred speech  Dizziness  Impairment in reaction time and tracking.

Cannabinoids and Driving Epidemiological Evidence Several studies support increased crash and culpability risk resulting from driving within two hours of smoking. More frequent cannabis exposure results in higher odds ratios for MVA’s of ~2.5 (i.e. 2.5 X more likely). Fatally injured cannabis positive drivers (other drugs may be present) had an adjusted OR of 8.6. Meta analysis of 16 published studies concluded an adjusted OR of between 2.66 and 1.92, in cannabis positive crash drivers.

Cannabinoids and Driving Experimental Evidence THC’s impairing effects increase with task complexity. Unexpected circumstances and choice during otherwise monotonous driving exhibit increased risk for errors over non cannabis using controls. Reaction time, road tracking, weaving, steering wheel variability, and brake latency all increase with recent cannabis exposure. THC effects on cognitive performance following smoking include immediate recall, executive functioning, working memory and attention.

Cannabinoids and Driving Experimental Evidence (cont’d.) Complex tasks involving multiple neurocognitive and neuromotor skills are particularly sensitive to THC. Driving simulator studies support dose dependant increases in weaving. Evidence of compensatory behavior in marijuana impaired drivers. There is evidence of tolerance to some acute effects in frequent users, however there is also evidence of long term reversible impairment in baseline performance in heavy chronic users following cessation.

Cannabinoids and Driving Experimental Evidence (cont’d.) Standardized Field Sobriety Tests are insensitive to THC in some cases where there is objective evidence of driving impairment. Cannabis use in conjunction with alcohol markedly increases the level of impairment. Hartman RL, Huestis MA. Cannabis effects on driving skills. Clin Chem Mar;59(3):

Farrell et al, JFS, June 2007 DrugFrequency Cannabis39 Benzodiazepines37 Cocaine37 Hydrocodone30 Morphine/Codeine28 Methamphetamine26 Carisoprodol/Meprobamate26 Oxycodone16 Methadone12 Antidepressants11 Zolpidem Top Drugs in DUID Labs Number of surveyed Toxicology labs listing cannabis and other drugs in their top 10 drugs.

2012 Top Drugs in DUID Labs Compound Number in Top 20 THC and metabolites13 Alprazolam/Met.13 Diazepam/Nordiazepam13 Cocaine and metabolites13 Morphine13 Oxycodone12 Hydrocodone12 Carisoprodol/Meprobamate11 Zolpidem11 Methamphetamine9 Clonazepam/ Met.9 Amphetamine9 Methadone9 Lorazepam9 Codeine7 Diphenhydramine6 Tramadol6 PCP5 Hydromorphone5 Compound Number in Top 20 Citalopram4 Temazepam3 Oxazepam2 Trazodone2 Oxymorphone2 Butalbital2 Dihydrocodeine2 Pseudoephedrine2 6-acetylmorphine2 Fentanyl2 MDMA2 Fluoxetine/ Met.1 Venlafaxine/ Met.1 Gabapentin1 Cyclobenzaprine1 Amitriptyline1 Topiramate1 Logan et al, JAT, Sept 2013

Drugs in Arrested Drivers 92 DUI Drivers arrested in Miami, tested for alcohol and drugs. Alcohol-free impaired drivers: 72% positive for THC High BAC drivers: 22% positive for THC Logan et al, JAT, June 2014

Drugs in Injured Drivers 108 Drivers admitted to a level-1 trauma center. Tested in urine for major drugs of abuse and impairing therapeutics. 26.9% positive for THC 33% of alcohol drivers also positive for THC Walsh et al, Alc Anal Prev, 2005

Drugs in Surveyed Drivers  2007 US National Roadside Survey  Conducted in Fall 2007  7000 drivers at 63 sites  6000 Oral Fluid Samples  3000 Blood samples  Tested for therapeutic and abused drugs  Preliminary results July 2009

2007 National Roadside Survey DrugPositivity THC8.65% Cocaine3.92% Hydrocodone0.68% Oxycodone0.82% Alprazolam0.64% Methamphetamine0.84% Sertraline0.50% Propoxyphene0.52% Tramadol0.46% Diazepam0.38% Amphetamine0.45% Fluoxetine0.37% Phentermine0.26% Dextromethorphan0.22% Methadone0.19% Nightime Positivity – Blood and Oral Fluid  2.2% of randomly tested drivers positive for alcohol >0.08g/100mL  16.3% positive for drugs other than alcohol.  ~80% of positives accounted for by ~20% of the drugs.  Cannabis use #1 at 8.65%

Drugs in Fatally Injured Drivers 397 fatally Injured Drivers State of WA, Tested in blood for major drugs of abuse and impairing therapeutics. 12.7% positive for cannabinoids 17.3% of alcohol positive cases positive for cannabinoids Schwilke et al, 2006

Changing US Attitudes to MJ November 2012 WA State and CO legalize possession by adults of 1oz of useable MJ for recreational use. Regulate and tax sale and distribution of marijuana. Focus enforcement on illegal marijuana trade, and DUID November 2014 OR, AK, and Washington D.C. follow suit

Marijuana DUI post Legalization Colorado The new law went into effect in January The THC percent positivity rates for January-February data were 21%, 38%, 45% and 48% in 2011, 2012, 2013 and 2014, respectively. The positive rate appears to be steadily increasing and the increase was statistically significant. There was no significant difference between 2012 and 2013, 2012 and 2014 or 2013 and 2014 (Pearson's chi-squared test at a=0.05). S. Urfer, J. Morton, V. Beall, J. Feldmann, and J. Gunesch, “Analysis of Δ9- tetrahydrocannabinol driving under the influence of drugs cases in Colorado from January 2011 to February 2014,” J. Anal. Tox., vol. 38, no. 8, pp. 575–581, Oct

Marijuana DUI post Legalization Washington The new law went into effect in January 2014*. The percentage of tested impaired driving cases which were positive for Delta-9 THC in whole blood at concentrations at or above 5 ng/mL were 18.6% and 24.9% in 2012 and 2013, respectively A significant increase (p=0.05) was noted between the pooled prevalence, pre-legislation and the post- legislation of confirmed positive THC cases, implying higher rates of use in the impaired driving population. F. J. Couper and B. L. Peterson, “The prevalence of marijuana in suspected impaired driving cases in Washington state,” J. Anal. Toxicol., vol. 38, no. 8, pp. 569–574, Oct

NMS Labs DUID Marijuana Data 36,037 cases drawn from DUID arrests. 17,612 (48.8%) cases between Aug 2009 and Oct 2014 presumptively positive for cannabinoids (ELISA, c/o 5ng/mL). 13,988 (79.4%) confirmed positive for one of THC (1ng/mL), THC-COOH, (5ng/mL), or THC-OH (5ng/mL). 7,448 cases were also screened for alcohol and other drugs: benzodiazepines, opiates, cocaine metabolite, amphetamines, methadone, phencyclidine, barbiturates, and propoxyphene. 6,877 cases had available gender, age, alcohol/other drug data: 80.6% male; Mean/median age 29/25; Range, 15-75

Demographics Other Drugs (+)Other Drugs (-)Total Alcohol (+)1,159 (15.6%)3,178 (42.7%)4,337 (58.2%) Alcohol (-)1,279 (17.1%)1,832 (24.6%)3,111 (41.8%) Total2,438 (32.7%)5,010 (67.3%)7,448 (100%) Table 1. 7,448 Confirmed Cannabinoid Positive Cases with Alcohol and Other Drug Data.

Demographics Table 2. Rates of other drug and alcohol positives within cannabinoid positive cases. Drug Class Cannabinoid cases positive by other drug class (%) Alcohol58.2% Opiates18.3% Benzodiazepines16.0% Cocaine /Mets8.49% Amphetamines6.42% Methadone3.42% Phencyclidine1.14% Barbiturates0.71% Any Other Drug32.7% * p<0.05, difference in proportions test.

Concentrations Table 4. Percentage of cases that meet various per se thresholds for DUID, based on a 1ng/mL c/o >1 ng/mL THC (Above per se threshold in PA) >2ng/mL THC (Above per se threshold in OH, NV) >5ng/mL THC (Above per se threshold in WA, CO, MT) + Cannabinoid79.5%60.3%29.6% + Cannabinoid + Alcohol + Other Drug 71.9%47.8%19.0% + Cannabinoid + Alcohol - Other Drug 79.4%56.8%23.5% + Cannabinoid - Alcohol + Other Drug 74.6%55.5%28.6% + Cannabinoid - Alcohol - Other Drug 90.51%78.9%49.3%

Impact of 5ng/mL THC per se Law 10,144 Marijuana DUID /DRE cases testing positive for THC and/or metab.

Impact of 5ng/mL THC per se Law 10,144 Marijuana DUID /DRE cases testing positive for THC and/or metab.

Conclusions Cannabis use under typical conditions creates a high- risk of impairment for 2-4 hours after dosing. When used with alcohol, risk of impairment increases substantially. Cannabis use is the drug category most frequently detected in arrested, injured, and fatally injured drivers after alcohol. There is no basis for setting a 5ng/mL per se standard for THC at ~2 hours post-driving to reflect the level at the time of driving.

Conclusions 81% of all cannabinoid drivers are below 5ng/mL at the time of the test. 51% of drivers using only marijuana are below 5ng/mL at the time of the test. 76.8% of cannabinoid positive drivers are also positive for alcohol (60%), or other drugs (33%). Optimum solution is objective impairment assessment using tools like the DRE program, with toxicological confirmation of use at an analytically based cut-off of 1ng/mL.

Questions and Discussion