chapter 62 Substance (drug and alcohol) misuse
WHY PEOPLE USE DRUGS
The collective impact of drugs of abuse is that neurotransmitter release is occurring as a result of direct stimulation of brain pathways, rather than their stimulation by sensory input. The ease, reliability, intensity and rapidity of such effects go a large way towards explaining the potential for such drugs to lead to abuse. The underlying brain structures and processes responsible for drug-related reinforcement are at least partially under genetic control. For example, studies suggest that the heritability of liability to alcohol abuse is 50%.
DRUG USE AND HEALTH
DOCTORS AND SUBSTANCE ABUSE
MEDICAL AND PSYCHOSOCIAL PROBLEMS
SPECIFIC SUBSTANCE ABUSE
ALCOHOL
Excessive alcohol consumption is a major risk factor for morbidity and mortality. The WHO estimates that, worldwide in 2002, alcohol caused 3.2% of deaths (1.8 million) and 4.0% of the burden of disease.1 In Australia, for example, it has been estimated that harm from alcohol was the cause of 5.3% of the burden of disease for males and 2.2% for females.2 In Australia in 1998–99, the total tangible cost attributed to alcohol consumption (which includes lost productivity, healthcare costs, road accident-related costs and crime-related costs) was estimated at $5.5 billion. Nevertheless, some benefits are thought to arise in the longer term from low to moderate alcohol consumption, largely through reduced risk of stroke and ischaemic heart disease. The net harm associated with alcohol consumption, after taking these benefits into account, was around 2.0% of the total burden of disease in Australia in 2003.3
The effects of alcohol on the central nervous system (CNS) vary according to the blood alcohol concentration, starting with mild euphoria, muscle relaxation and pleasure, possibly through release of noradrenaline, dopamine and endogenous opioids; then impairment of performance, especially of complex tasks; then ataxia and slurred speech, intellectual impairment and amnesia; and finally, profound depression and progressive loss of consciousness, respiratory failure and death.
Chronic alcohol intoxication
Wernicke’s encephalopathy is an acute, reversible condition, seen in chronic alcohol-dependent individuals, characterised by ataxia, ophthalmoplegia and confusion. Not all of the classical triad of signs need be present for the diagnosis to be made. Indeed, it is underdiagnosed by up to a factor of 80% on this basis. Thiamine is required to act as an enzyme co-factor for pyruvate kinase, at the conclusion of glycolysis in the cytosol. It is mandatory for the production of high levels of ATP, produced via the Krebs cycle in mitochondria. Its absence causes significant under-utilisation of carbohydrates in the form of anaerobic over aerobic metabolism. Essentially the brain is starved of energy despite a high carbohydrate load. Despite the enormous variance of alcohol detoxification protocols and choice of detoxification agents used across the world, the single most important drug and the one common theme to all protocols is thiamine. In the absence of signs, parenteral (IV or IM) thiamine 100 mg q8h is thought to be sufficient prophylaxis.
Current guidelines5
Tools to assess alcohol intake:
Management
Integrative approaches
Herbal medicines7
Herbal treatments such as St John’s wort (Hypericum perforatum), kudzu extracts (Pueraria lobata), panax ginseng, dried roots of S. militorrhiza (a Chinese medicine used for insomnia) and ibogaine (from a Central African root bark) may reduce alcohol consumption.8 While the mechanisms of action remain to be clarified, they probably act through several neurotransmitter systems. St John’s wort may provide some relief from comorbid depression.
Silybum marinarum (milk thistle)—silymarin, the flavonoid extracted from milk thistle, has been studied for treating all types of liver disease. Silymarin has the ability to block fibrosis, a process that contributes to the eventual development of cirrhosis in people with inflammatory liver conditions secondary to alcohol abuse.9
Dietary advice
TOBACCO
Nicotine is selective for the nicotinic acetylcholine receptor. There are two major types of these receptors: at the skeletal neuromuscular junction, and at acetylcholine receptors in the brain and autonomic ganglia.
Dependence and withdrawal
Craving, while not a diagnostic criterion, is an important element in withdrawal.
Helping smokers to quit
There is good evidence that brief advice from healthcare providers to quit has a small effect: 2–3% of quitters one year later. This effect can be increased by adding other strategies including pharmacotherapy, active follow-up, and referral to quit-smoking services. The 5 A’s approach10 is recommended:
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