The recommendations for DSM-5 substance use disorders represent the results of a lengthy and intensive process aimed at identifying problems in DSMIV and resolving these through changes in DSM-5. At the same time, the variable amount of evidence on some of the issues points the way toward studies aimed at further clarifications and improvements in future editions of DSM.The COVID‐19 pandemic has left consumers disinclined or unable to venture out for alcohol and cannabis , increasing demand for home delivery services. Given the scale to which this business has grown, home deliveries could become an established source of legal intoxicants, along with brick‐and‐mortar outlets, in many countries. This phenomenon has been notably under‐researched by addiction scientists despite its implications for health, research, and prevention policy. Alcohol and cannabis home delivery were expanding before COVID‐19. Alcohol delivery was already thriving in the UK, US, Canada, France, China, Japan, Argentina, Philippines, Thailand, and Australia. In China and the UK, more than 50% of consumers purchased delivery alcohol at least monthly in 2018. The pandemic, however, is accelerating this trend in ways that could alter consumer habits for good. In Mexico, Kenya, the US, and Canada, alcohol delivery companies have reported manifold increases in sales during the pandemic, including among first‐time users. Although illegal in most countries, cannabis delivery is abundant in several US states and Canadian provinces, with California maintaining the world’s largest retail market. The online finder, Weed maps, reports that only 450 California neighborhoods have brick‐and‐mortar cannabis outlets yet home delivery is currently available in 22 500. Prompted by COVID‐19,hydroponics flood table many governments are changing longstanding public health regulations designed to limit availability of legal intoxicants.
In parts of the UK, Australia, Canada, and most US states, governments have relaxed alcohol regulations for off‐premise sales, takeout, and home delivery, either by affirmatively allowing this or by not enforcing existing prohibitions. These measures may skirt open container laws and delivery permit requirements. Complete or partial bans on alcohol sales have been implemented during pandemic lock downs in some places, including India, South Africa, Greenland, and Mexico yet this can increase demand for delivery. Post‐pandemic, delivery businesses could constitute a new industry stakeholder pressuring governments to maintain newly relaxed policies. The growing preponderance of home delivery, and changing government regulations, could have profound implications for public health. Yet empirical research examining impacts on consumption, health, or social problems is sparse. A Google Scholar search of “ AND ” yielded only two relevant peer‐reviewed studies in the first 200 hits. We propose four recommendations to address this gap. First, researchers should reexamine evidence on the causal effects of alcohol and drug availability in light of home deliveries. We need conceptual models predicated on the possibility that home delivery could fundamentally alter patterns of alcohol and cannabis consumption. The established impacts of brick‐and‐mortar outlets may no longer hold or could vary by the extent of available delivery. Conversely, delivery effects may depend on the density and perceived convenience of existing brick‐and‐ mortar outlets, making regions that restrict density more conducive to delivery becoming an important form of availability from a public health perspective. Delivery could replace or complement sales through brick‐and‐mortar outlets, with differing implications for population‐level consumption. These changes will likely depend on factors not typically measured in availability research, such as digital literacy and social media penetration. Second, by changing who is consuming, how much is consumed, and where it is consumed, home delivery could alter the epidemiology of alcohol and cannabis harms. Researchers should consider new types of harms—for example, crimes victimizing drivers transporting cash and valuable goods.
If home delivery substitutes for on‐premise consumption , the distribution of problems could shift from public environments towards private venues . Home‐based consumption and corresponding harms are more likely to be overlooked and could pose challenges for epidemiologic surveillance because “hidden” problems tend to be underreported. For now, researchers will likely struggle with disentangling the impact of delivery businesses on alcohol‐ and drug‐related harms from the secondary effects of the pandemic itself .Home delivery requires researchers to rethink methods for availability research, currently dependent on geospatial analyses of brick‐and‐mortar outlets. Proximity‐based methods for linking harms to outlets in physical space have no clear analogue for delivery. Direct‐observation outlet censuses are the gold standard for research on brick‐and‐mortar outlets. Yet the universe of home delivery transactions cannot be fully observed and services may not deliver to fixed regions. If the regions served by delivery businesses can be mapped, spatial risk surface modeling strategies should be considered. Crowd‐sourced directories—e.g. Weedmaps, Tipple—can capture brick‐and‐mortar outlets and should be explored for measuring delivery. Data from delivery service manifests, state‐mandated track‐and‐trace systems, and deliverer cellular location data should be explored too. Finally, researchers should engage proactively with policymakers about the public health implications of home delivery and policy approaches to compensate. WHO recommends maintaining alcohol availability restrictions during the pandemic; expanding home delivery goes directly against this. Where home delivery undermines existing regulations, evidence to guide adaptations is limited. Cross‐national research comparing diverse regulatory schemes could help address this gap. Unsupervised transactions present challenges for enforcing minimum age laws. Indeed, the Philippine and Thai governments plan to ban online alcohol sales due to concerns about underage drinking. Responsible server laws banning service to intoxicated persons must be re‐envisioned. In one Australian study, 20% of alcohol delivery patrons reported using the service because they were too intoxicated to drive and 36% said that without the service, they would have had to stop drinking. Amplified pricing and marketing controls should be considered as potential levers to mitigate these concerns.
In many parts of the world, the COVID‐19 pandemic is accelerating a pre‐existing trend towards alcohol and cannabis home delivery while prompting loosened regulations that could prove difficult to roll back. Although some increases due to the pandemic will wane, home delivery could be here to stay. Addiction researchers should gear up to study the consequences. This calls for rethinking alcohol‐ and drug‐availability theory, while transforming existing brick‐and‐mortar geospatial approaches using novel data streams and methods. Tackling fundamental questions of causal inference presented by deliveries could inform availability theory and suggest innovations for prevention policy.Methamphetamine is a highly addictive and widely used psychostimulant that induces adverse effects on the central nervous system , predominantly through alteration of monoaminergic pathways. Chronic exposure to MA and other amphetamines is associated with a host of neurotoxic processes including gliosis, neuronal apoptosis, oxidative stress, brain thermotoxicity, and neuroinflammation . Consequently, conditions of neurochemical and cerebrovascular abnormalities, including increased blood–brain barrier permeability and ischemic stroke, are more prevalent among stimulant users and can disrupt neural circuits, particularly fronto-striatal systems that support neurocognitive abilities. It has been widely documented that MA-dependent individuals are vulnerable to a constellation of neurocognitive deficits including impairments in episodic memory, executive functioning, working memory, information processing speed, verbal fluency, attention, and motor skills . Whereas it is evident that MA dependence is associated with neurocognitive dysfunction, the severity of such neurocognitive deficits remains unclear. Synthesis of clinical studies comparing neurocognitive profiles of MA-dependent individuals to non-using controls not only indicates a mild-tomoderate deleterious effect of MA on neurocognition, but also reveals considerable inter-individual variability in which many MA-dependent persons perform within normative standards whereas others may exhibit severe deficits . Variation in use patterns of MA alone does not appear to account for these individual differences in vulnerability to MA-related brain dysfunction as the existing human literature has generally failed to find a consistent dosedependent relationship between MA exposure parameters and neurocognitive impairment . Given the unimpressive predictive utility of MA exposure parameters as moderators of neurocognitive impairment,hydroponic stands susceptibility to MA-related neurocognitive dysfunction may be better explained by the influence of other modulating variables. Considering that MA is seldom used on its own, patterns of polysubstance use among primary MA users may modulate vulnerability to neurocognitive impairment. Alcohol is of particular interest as it is the most commonly used secondary substance among primary MA users and heavy drinkers are 4–5 times more likely to report using MA as compared to non-drinkers . The detrimental effects of chronic excessive alcohol consumption on CNS and neurocognitive functioning have been extensively studied. Briefly, heavy alcohol-related risks for brain damage include disruption to neurotransmitter systems, neuroinflammation, neurodegeneration, and cerebrovascular disease . Long-term alcohol misuse has been linked to alterations in frontal and limbic neural circuitry, most commonly resulting in neuropsychological deficits of episodic memory, problem solving, and cognitive control . Given that MA and alcohol independently disrupt overlapping neurobiological mechanisms, neuroanatomical structures, and neurobehavioral functions, one may expect a synergistic neurotoxic effect of combined MA and alcohol misuse.Additional animal model research has shown that concurrent exposures to MA and alcohol synergistically increase oxidative stress in the rat hippocampus and contribute to behavioral impairments in learning, discrimination, and spatial working memory above and beyond the effects of either substance alone .
In vitro human brain tissue models provide converging evidence that both alcohol and MA impair glucose metabolism in astrocytes and neurons, a process that is a precursor to oxidative stress-mediated neurotoxicity . Although less is known about combined MA and alcohol-induced biological damage in vivo, there is evidence that acute as well as repeated concurrent exposure induces adverse vascular effects, including increased heart rate and myocardial oxygen consumption . Consistent with neurocognitive profiles of adult MA users, pediatric studies demonstrate that prenatal exposures to MA and alcohol synergistically damage fronto-striatal networks and compromises working memory abilities in children aged 5–15 . Chronic exposure to cocaine, another potent psychostimulant, is associated with moderate deficits in neurocognition across a range of domains, with the largest effects in executive function, working memory, and verbal learning/memory . Whereas combined cocaine and alcohol use has been linked to altered neurophysiological activity , including abnormal cerebral blood perfusion , elevated heart rate and cortisol levels , and dysregulated dopaminergic and serotonergic transmission , literature on the neurocognitive effects of comorbid cocaine and alcohol use disorders is mixed. Some studies report that increasing alcohol use provides an additive deleterious effect on neurocognition in primary cocaine users and can also attenuate improvements in verbal memory following abstinence from cocaine . Nevertheless, others have failed to detect a significant impact of alcohol consumption on neurocognition in the context of cocaine dependence . Although combined alcohol and MA misuse is common and may result in a convergence of mechanisms of neural injury, it remains unclear how historical patterns of alcohol use relate to neurocognitive functioning among primary MA users. Therefore, the current study aimed to address this gap in knowledge by examining the relationships between a continuous estimate of lifetime alcohol consumption and neurocognitive functioning in a sample of MA-dependent and MA-nonusing individuals. We hypothesized that greater reported lifetime alcohol consumption would contribute to poorer neurocognitive functioning regardless of MA dependence, but would exhibit significantly larger effects among MA-dependent individuals compared to MA-nonusing persons. Examination of these associations may assist in identifying specific risk factors for neurocognitive impairment among MA-dependent individuals, and may guide development of targeted polysubstance use prevention and treatment strategies for this population.Eighty-seven MA-dependent and 114 MA-nonusing comparison participants were evaluated at the HIV Neurobehavioral Research Program at the University of California, San Diego , as part of federally funded, institutionally approved projects focusing on neuroAIDS effects of methamphetamine. All were recruited from substance dependence recovery programs or from the general San Diego community, and gave written informed consent as approved by the UCSD Institutional Review Board. Participants were confirmed to be HIV and HCV uninfected by standard antibody testing and were free of medical conditions that might confound interpretation of neurocognitive testing results, such as traumatic brain injury, stroke, or epilepsy. The MAþ individuals met criteria for a lifetime diagnosis of MA dependence according to the Structured Clinical Interview for DSM-IV , with use within the previous 18 months. The MA− group consisted of participants who never met criteria for amphetamine use disorders and were not habitual users of any stimulant. Exclusion criteria for both groups included other substance dependence, except alcohol or cannabis, within 5 years, or abuse within the past 12 months.