Cannabis Use and Cognition in Adults Prescribed Opioids for Persistent Pain
Megan Wildes, Teresa L. Bigand, Matthew E. Layton, , Marian Wilson
Pain Management Nursing, 2019, 1-6.
Doi : 10.1016/j.pmn.2019.06.014
a b s t r a c t
Background : Adults with persistent pain frequently report cannabis use to help manage their symptoms. The impact of cannabis use on cognition in the presence of concurrent symptoms of depression and anxiety is poorly understood.
Aims : Our study explored how cannabis use affects relationships among symptoms of depression, anxiety, and cognition.
Design : A cross-sectional survey study was conducted.
Settings : Surveys were distributed at outpatient clinics treating adults for pain in the Pacific Northwestern United States.
Participants : A total of 150 adults prescribed an opioid medicine for persistent pain were recruited.
Methods : A pencil and paper survey was used to collect several self-reported ratings of cognition, symptoms of depression and anxiety, and the average potency of cannabis consumed as measured by the percentage of delta-9-tetrahydrocannibinol (THC) and cannabidiol (CBD), as well as frequency of cannabis use.
Results : Depression, anxiety and cognition significantly worsened as the reported percentage of CBD, THC and overall frequency of cannabis use in the past 30 days increased. Depression and anxiety both significantly predicted worsening cognition in the sample. The relationship between depressive symptoms and cognition was strengthened as reported percentages of CBD use increased. The relationship was the same for anxiety and cognition, although not as strong.
Conclusions : More cannabis use, particularly high CBD products, may be linked with increased symptom burdens and may strengthen relationships between negative affect and cognition. Further cannabis research within persistent pain populations is warranted to add evidence that can assist patients in managing mood and mental processes. Nurses should evaluate how negative affective health symptoms may impact cognition among adults with persistent pain using prescription opioid medications, especially in the context of concurrent cannabis use
Key Practice Points
- Depression, anxiety and cognition significantly worsened as the reported use of cannabis increased.
- More cannabis use, particularly high CBD products, strengthened relationships between mood and cognition.
- High symptom burdens exist despite use of cannabis and opioids.
The number of Americans with persistent (chronic) pain has risen to more than 50 million adults (20.4% of the country’s population), with 19.6 million reporting high-impact chronic pain that interferes with daily living and work (Dahlhamer et al., 2018). Although pain symptoms have traditionally been treated by opioids, prescribing opioids has been linked to an increase of opioid overdose deaths (Centers for Disease Control and Prevention [CDC], 2018a). Opioids are reported as the second leading cause of accidental death in the United States and the cause of 55% of reported overdose deaths (CDC, 2018a, 2018b). Given concern for addiction and opioid misuse, along with evidence suggesting long-term use of opioids may provide suboptimal pain control, alternative pain managements strategies are needed (National Center for Complementary and Integrative Health [NCCIH], 2016; Vowles et al., 2015). One possible pain management strategy is the use of cannabinoids, derivatives of the cannabis plant, that are postulated to reduce suffering in people with persistent pain while presenting less dangerous side effects than opioids (Haroutounian et al., 2016; National Institute on Drug Abuse [NIDA], 2018; NCCIH, 2016).
Cannabinoids, chemicals from the cannabis or marijuana plant that target the endocannabinoid system in the body, potentiate pain moderation, and inhibit psychological perception of pain through their impact on neurotransmitters (National Academies of Sciences Engineering Medicine [NASEM], 2017). Two main cannabinoids (of which there are many) are tetrahydrocannabinol (THC), which has psychoactive elements, and cannabidiol (CBD), which presents with fewer psychoactive effects than THC (NASEM, 2017; NIDA, 2018). Cannabinoids occur naturally in hemp and the cannabis plant and are found in varying percentages and consumed in various ways, such as edibles, tinctures, creams, and/or products to be smoked and vaped. Individuals in the United States and worldwide report using cannabinoids in these various forms for their potential medicinal value in managing persistent pain, anxiety, and depression (Campbell et al., 2018; Corroon, Mischley, & Sexton, 2017; NASEM, 2017; Reiman, Welty, & Solomon, 2017).
Although cannabis is listed by the U.S. Drug Enforcement Agency (DEA) as a Schedule I drug with no medicinal value and high abuse potential (NASEM, 2017; U.S. DEA, n.d.), over the past decade, reported heavy cannabis usage (high prevalence and intensity in the prior month) has increased in the United States. Recent policy changes in several U.S. regions legalized cannabis for both medicinal and recreational purposes. Although improved access to cannabis may prompt its use as a substitute for opioid use among those with pain (Bradford & Bradford, 2016; Reiman et al., 2017; Whiting et al., 2015), reports on cannabis benefits are mixed.
Users of cannabis for medicinal reasons have reported benefits such as improved sleep (Corroon et al., 2017) and decreased opioid usage (Bradford & Bradford, 2016; Reiman et al., 2017), but other studies
note increased risk for anxiety (Kedzior & Laeber, 2014). A metaanalysis of 24 clinical trials with more than 2,300 participants found that the use of cannabis for chronic pain, neuropathic pain, and spasticity caused by multiple sclerosis is supported by highquality evidence (Hill, 2015). However, other studies have reported either no improvement in reported pain (Campbell et al., 2018) or the development of new psychosis in those already genetically or environmentally susceptible to experiencing mental health diseases (Corroon, 2017).
Cognition is of particular importance in populations with persistent pain because it is adversely affected by both severity of pain symptoms and opioid medications (Farmer, Baliki, & Apkarian, 2012; Liu, Li, Tang,Wu, & Hu, 2014). Studies support loss of cortical matter (Apkarian et al., 2004) and brain remodeling among individuals with persistent pain (Berryman et al., 2004; Liu et al., 2014; Metz, Yau, Centeno, Apkarian, & Martina, 2009). Yet many studies investigating cognitive and neurologic changes fail to control for other pain modulators such as anxiety, depression, social support, and sleep (Boakye et al., 2016; Bradford & Bradford, 2016; Haroutounian et al., 2016; NIDA, 2018; Reiman et al., 2017).
The impact of medical cannabis on cognition is debatable; the National Academies of Science suggest impaired cognition from CBD use can occur in the areas of attention, memory, and learning (NASEM, 2017). Other studies suggest that at high doses of CBD, there are no improvements in cognition and there is decline in neural functioning and increased reports of sedation (Boggs et al., 2018). Co-occurring anxiety and depression can also impair cognitive functioning (Saffer, Lanting, Koehle, Klonsky, & Iverson, 2015). Yet the presence of social support may be a protective factor against anxiety and depression (Hughes, Jaremka, Alfano, Glaser, & Kiecolt-Glaser, 2014), potentially changing the impact of such negative affective health symptoms on cognition. Interrelated social, cognitive, and mental health factors require scientific exploration to guide clinical decision making. Therefore our study investigated the relationships among cognition, affective health symptoms, social support, and cannabis use (including estimated use of CBD and THC) in adults with persistent pain.