Cannabis and Driving

We have all heard about how dangerous it can be to drive while intoxicated. And when most of us think of intoxication, we think of alcohol. However, there are many other things that can intoxicate us and impair our driving including pills, medications and cannabis.

Cannabis is becoming more popular for the medical benefits. Because it is more commonly accepted, the law is cracking down making sure there are no cannabis impaired motorists on the streets. But how bad is driving while intoxicated on cannabis? Read on to find out.

THC and Motor Skills

Let’s start by considering how THC works in the body.

People who use marijuana have differences in the area of the brain called the corticostriatal networks, compared to those who don’t. These are connected to motor learning and control and can affect reaction time, memory and the ability to switch between tasks.

However, results on how THC actually affected motor skills were inconsistent.

One study showed that frequent THC users had poorer memory then non-users and reduced activity in the cerebellum, an area of the brain linked to motor skills.

Another study prompted frequent users and non-users to push a button in response to select

stimuli. In this study, both groups made the same amount of mistakes but the non-users were more aware of their mistakes than the frequent users were.

Further research has been done with wildly varying results. Some evidence shows those who use marijuana sporadically will experience more impairment of motor skills while intoxicated while those who use regularly will experience less impairment. This is likely due to a tolerance that builds up in frequent users.

Basically, the research that has been gathered shows wide gaps in finding any conclusive evidence on how marijuana affects motor coordination. This may be due to the fact that there were many variables in the studies that were not accounted for.

These include:

• Whether the skills being studied were new for the users or ones they were already familiar with
• Whether participants were frequent or occasional users
• Whether users combined THC use with alcohol
• Small sample sizes may have also been to blame

So, although it’s likely that THC affects motor skills, there seems to be no conclusive evidence on how substantial these effects are. So what does this mean when considering driving and THC use?

THC and Driving

Before continuing, let’s consider that there are different types of cannabis. THC is well known for its mind-altering abilities and therefore has the most potential be dangerous when used before or while driving a vehicle.

70% of people polled who drive on marijuana say they don’t feel the intoxication caused by cannabis is much of an issue, while the other 29% think it is a serious problem.

This is in contrast to 79% of Americans who think drinking while impaired by alcohol is a very serious problem. Alcohol causes a third of all fatal accidents, so let’s take a look at how much of a risk it is to drive while high on marijuana.

Studies show that, although it does impair driving abilities, there is no proof that marijuana can increase chances of accidents. In fact, it may actually reduce chances of them occurring.

This may be due to the fact that those intoxicated by marijuana are more aware that they are impaired and compensate effectively by driving more slowly, passing less and leaving more space for cars in front of them.

This is in comparison to those intoxicated by alcohol who may not be as aware of their impairments and may follow cars more closely, speed and perform other actions that make accidents more likely.

However, even though these statistics exist, there is no doubt that marijuana impairs driving abilities. It impairs motor coordination, visual function and divided attention.

Drivers intoxicated by THC are also more likely to weave within their own lane than sober people, but they did not weave out of their lane or speed, as a person intoxicated by alcohol would.

Another interesting thing to consider is that after medical marijuana laws passed, there was actually a reduction of traffic fatalities with the sharpest reductions being evening and drunk driving and alcohol related accidents.

Experts feel this may be due to the fact that individuals are now choosing to take THC as an alternative to drinking alcohol although more research would be needed to this.

How Do We Prove THC Intoxication?

Despite the fact that marijuana is not likely to increase the risk of accidents, backing this up with statistics is a bit trickier.

Statistics show that 11% of drivers killed in accidents had taken at least one drug, but whether this drug was marijuana was unclear.

The lack of clarity owes to the fact that there is no way to measure marijuana with a breathalyzer. While blood tests can be used, this can also be deceiving since concentrations of the drug tend to stay high in the blood of chronic users.

It is also difficult for officers to determine if drivers are intoxicated by doing roadside tests like ‘touch your nose’ or ‘walk in a straight line’ as marijuana does not always affect motor skills in this way. These tests are somewhat effective but only catch about 30% of high drivers. Novice pot smokers tend to do worse on them while chronic smokers can ace these tests.

Other points make it even more difficult to determine what constitutes as intoxicated driving. Especially when considering THC use and whether or not THC is to blame for the accident occurring.

These include the fact that drivers are not always tested for drug use, especially if they have an illegal blood alcohol concentration level because that is enough evidence to constitute driving while impaired.

Furthermore, when tested for substance use following a car crash, drivers may have THC, alcohol and other drugs in their system making it difficult to determine what was responsible for the crash.

This creates a dilemma. There is a law in place prohibiting driving while on THC, but how effectively can we enforce these laws?

Legal Limits

Despite the fact that determining a point of intoxication is difficult, there are legal limits that apply to THC consumption while driving. In the Drug and Alcohol Dependence study, lane weaving began when a person’s blood levels reach 13 micrograms per each liter of blood. Interestingly enough, this compares with a .08% alcohol content which is the legal limit for alcohol in most states.

However, the legal limit for THC can vary from state to state. Washington and Colorado, for instance, call it at 5 micrograms per liter. Rhode Island, Pennsylvania and Indiana do not permit driving with any amount of THC in the bloodstream.

In traffic fatality studies, any amount of THC in the blood, no matter how tiny, will count as a positive drug test. For reference, one joint can raise THC levels to about 20 micrograms per liter.

CBD and Driving

Aside from THC, there are other constituents found in cannabis that can also provide health benefits. One that is rising in popularity is CBD.

CBD is known for improving wellness without providing mind-altering effects. However, it can impact mood and alertness due to the alterations it causes in brain chemistry. So does this mean it’s safe to use while driving?

CBD affects serotonin receptors when taken in high doses. It also works as a reuptake inhibitor raising and maintaining levels of anandamide, an endocannabinoid similar to THC. It inhibits the reuptake of adenosine, increasing levels of the molecule in the brain. This is how it works to reduce anxiety.

CBD may also work as an allosteric modulator of the GABA A receptor meaning it can enhance or inhibit receptor transmission. In doing so, the receptor binds more easily with the neurotransmitter GABA. GABA has an inhibitory effect on the nervous system inducing activity so that it produces states of calm and relaxation.

So what does this mean for driving?

For the most part, CBD will not affect driving. However, there are side effects that some users may experience as a result of the calming effects of CBD. These can be potentially dangerous; They include low blood pressure, light-headedness and drowsiness. These can be especially prevalent in those that take higher doses of the compound.

To make sure you are safe while driving, start out with lower doses and find out how CBD will affect you before attempting to take the wheel.

Although there seems to be a lot of back and forth on how THC can affect driving, the bottom line is, it’s illegal and best to be avoided. If you are thinking of using THC consider the length of time your high will last. (High length can vary according to the form of THC you are taking and the amount you are consuming.) Once you have done that, plan your day so that driving will not be necessary during that time.

THC can be a very beneficial compound, but if you are going to be driving a vehicle, it’s just not worth the risk.