Drug abuse is a recurring pattern of harmful use of a substance despite adverse consequences of the substance in work, school, relationships, the legal system, or personal health. This may occur concurrently with or independently from substance dependence, in which there is the presence of physiologic tolerance, discontinuation-induced withdrawal, or inability to willfully control rate or discontinue substance.
EPIDEMIOLOGY & DEMOGRAPHICS
INCIDENCE (IN U.S.): For alcohol the incidence is 7%/yr.
PREVALENCE (IN U.S.):
• For alcohol: lifetime
• For cocaine abuse: lifetime prevalence is 0.2%
• For marijuana abuse: lifetime prevalence is 4%
• For amphetamine abuse: lifetime prevalence is 2%
• For hallucinogens: rate is 0.3%
• For opiates: rate is 0.7%
• For nicotine: lifetime prevalence of dependence is 20%
• For MDMA (3,4-methylenedioxymethamphetamine, or ecstasy): college student rate is 4.7%
• Males abuse substances more frequently than females.
• The rates of male:female substance abusers are as follows:
• Problematic use of substances may begin in early life (8 to 10 yr).
• The mean age of onset of problem drinking is about 25 yr for men and 30 yr for women.
• For most substances: 18 to 30 yr of age
• Men: average >20 yr of heavy drinking
• Women: average 15 yr of heavy drinking
• There is evidence of a nonspecific genetic factor.
• Vulnerability to alcohol abuse is increased in Asians with the alcohol dehydrogenase type 2 isozyme and the aldehyde dehydrogenase type 2 isozyme.
PHYSICAL FINDINGS & CLINICAL PRESENTATION
• Abuse of several substances generally occurs together (e.g., alcohol abuse is often found in association with abuse of or dependence on nicotine).
• Symptoms of anxiety, depression, insomnia, cognitive and memory dysfunction, and emotional/behavioral dyscontrol are frequent.
• Alcohol and cocaine abuse are specifically associated with violence and accidents (e.g., more than half of all murderers and their victims are intoxicated at the time of the crime).
Two models of addiction: (1) Conditioning-substance use paired with enforcing and triggering stimuli, and (2) Homeostatic-either preexisting abnormalities or drug-induced abnormalities lead to initial or continued use of the drug.
• Psychiatric disorders such as depression, mania, social phobia, or other anxiety disorders that coexist or occur as a consequence of substance abuse
• Cannot diagnose these disorders accurately in the setting of active substance abuse Table 1-1.
• The history is crucial for diagnosis of any substance abuse disorder; because of frequent denial and poor insight into problem substance abuse, collateral information from family, friends, and co-workers is often helpful.
• Observation of problematic behavior during intoxication or withdrawal is diagnostic.
• Physical examination findings are limited and not diagnostic (e.g., needle scars from repeated intravenous injections, rhinorrhea secondary to intranasal cocaine).
Most helpful tests: toxicology screen or blood alcohol level
• Not helpful in routine diagnosis and management of substance abuse, but possibly useful in the management of sequelae of substance abuse (e.g., head CT scan to evaluate the alcohol abuse-associated increased risk of subdural hematomas or increased evidence of cerebral atrophy)
• Liver ultrasound to evaluate for alcohol-related fatty changes
• Two-dimensional echo for intravenous drug use-associated valvular lesions
• Relapse prevention by avoidance of trigger stimuli or by uncoupling trigger stimuli from substance ingestion
• Self-help groups such as Alcoholics Anonymous, Narcotics Anonymous, and Al-Anon
• Nonpharmacologic strategies have greatest documented efficacy
ACUTE GENERAL Rx
• Acute interventions are usually confined to safe withdrawal in the setting of dependence.
• Benzodiazepines are safe and effective in acute alcohol withdrawal.
• Anticonvulsants, particularly carbamazepine, are used effectively in Europe.
• b-Blockers and clonidine should be avoided in alcohol withdrawal, because they mask markers of the severity of the withdrawal (blood pressure and pulse rate).
• Clonidine alleviates the discomfort of opiate and nicotine withdrawal.
• Nicotine patches and gum reduce withdrawal symptoms.
• Few agents are useful in prevention of substance abuse relapse.
• Disulfiram (Antabuse) workup and metronidazole (Flagyl): possible interaction with alcohol causes physical discomfort.
• Naltrexone helps reduce craving for alcohol.
• Adjunctive use of antidepressants or lithium is helpful when substance use is associated with anxiety and mood symptoms.
• Methadone replacement is used in opiate abuse/dependence (controversial).
• Substance abuse is a chronic relapsing illness.
• The goal of treatment is always abstinence, but success of treatment is measured by return of function and increasing duration between relapses.
• When substance abuse is complicated by another psychiatric illness, prognosis for both conditions is quite poor.
• Abuse of one substance increases likelihood for abuse of other substances.