Drug abuse, dependence, and addiction are complex issues with far-reaching consequences. This topic explores the definitions, diagnostic criteria, and neurobiology behind substance use disorders. It also covers common drugs of abuse and their effects on the brain and body.

Understanding the signs of drug abuse is crucial for early intervention. The notes delve into treatment options, including medications and behavioral therapies, highlighting the importance of integrated approaches in addressing addiction. This knowledge is essential for healthcare professionals working with diverse patient populations.

Defining drug abuse, dependence, and addiction

Key Concepts and Definitions

• Drug abuse involves harmful use of psychoactive substances leading to significant impairment or distress
• Drug dependence creates physiological adaptation characterized by tolerance and withdrawal symptoms
• Addiction manifests as a chronic, relapsing disorder with compulsive drug seeking despite consequences
• Abuse and addiction differ in symptom severity and degree of control over drug use
• DSM-5 combines substance abuse and dependence into a single disorder on a mild to severe continuum
• Physical dependence can occur without addiction in some medical treatments
• Addiction always involves a psychological component

Diagnostic Criteria and Clinical Implications

• DSM-5 criteria for substance use disorders include impaired control, social impairment, risky use, and pharmacological criteria
• Tolerance develops as higher doses are needed to achieve the same effect
• Withdrawal symptoms emerge when drug use is discontinued (nausea, sweating, anxiety)
• Craving involves intense desire or urge to use the substance
• Continued use despite physical or psychological problems caused or exacerbated by the substance
• Clinical assessment involves comprehensive evaluation of substance use patterns, medical history, and psychosocial factors

Common drug classes associated with abuse

Central Nervous System (CNS) Depressants

• Alcohol depresses CNS activity leading to relaxation and reduced inhibitions
• Benzodiazepines (Xanax, Valium) enhance GABA neurotransmission causing sedation and anxiolysis
• Barbiturates (phenobarbital) also enhance GABA activity but carry higher risk of overdose
• GHB produces euphoria and sedation by acting on GABA and GHB receptors
• Abuse potential stems from pleasurable effects and risk of physical dependence

Stimulants and Psychostimulants

• Cocaine blocks dopamine reuptake creating intense euphoria and increased energy
• Amphetamines (Adderall) and methamphetamine increase dopamine and norepinephrine release
• MDMA (ecstasy) causes serotonin release leading to empathogenic and stimulant effects
• Caffeine mildly stimulates the CNS by blocking adenosine receptors
• Nicotine activates nicotinic acetylcholine receptors producing stimulation and relaxation

Opioids and Analgesics

• Heroin rapidly crosses the blood-brain barrier producing intense euphoria
• Prescription opioids (oxycodone, hydrocodone) bind to opioid receptors for pain relief
• Fentanyl is a potent synthetic opioid with high abuse potential and overdose risk
• Kratom contains opioid-like compounds with stimulant effects at low doses
• Tramadol has both opioid and serotonergic activity leading to analgesic effects

Hallucinogens and Dissociatives

• LSD activates serotonin receptors causing powerful alterations in perception and cognition
• Psilocybin (magic mushrooms) produces similar effects to LSD but with shorter duration
• Ketamine acts as an NMDA receptor antagonist causing dissociation and analgesia
• PCP also antagonizes NMDA receptors leading to more intense dissociative effects
• Salvia divinorum activates kappa opioid receptors causing brief but intense hallucinations

Neurobiology of drug addiction

Reward Pathway and Dopamine Signaling

• Mesolimbic dopamine system mediates reinforcing effects of drugs of abuse
• Ventral tegmental area (VTA) projects dopamine neurons to nucleus accumbens (NAc)
• Drugs increase dopamine release in NAc creating pleasure and reinforcing behavior
• Natural rewards (food, sex) also activate this pathway but to a lesser extent
• Repeated drug use leads to neuroadaptations reducing sensitivity to natural rewards
• Drug-related cues trigger dopamine release and craving even in absence of drug

Neuroplasticity and Synaptic Changes

• Long-term potentiation (LTP) strengthens synaptic connections associated with drug use
• AMPA receptor trafficking increases excitatory transmission in NAc
• Dendritic spine density changes alter synaptic plasticity and learning
• Brain-derived neurotrophic factor (BDNF) signaling contributes to drug-induced plasticity
• Epigenetic modifications lead to persistent changes in gene expression
• Synaptic pruning in prefrontal cortex impairs executive function and decision-making

Tolerance and Withdrawal Mechanisms

• Downregulation of receptors reduces drug sensitivity requiring higher doses
• Upregulation of cAMP pathway contributes to tolerance development
• Homeostatic adaptations in neurotransmitter systems oppose drug effects
• Withdrawal results from rebound effects when drug is removed from system
• Glutamate signaling plays key role in withdrawal and drug-seeking behavior
• Stress hormone systems become dysregulated contributing to negative affect

Recognizing signs and symptoms of drug abuse

Physical Manifestations

• Changes in sleep patterns (insomnia or hypersomnia) disrupt circadian rhythms
• Appetite fluctuations lead to unexplained weight loss or gain
• Deterioration in personal hygiene and grooming habits becomes noticeable
• Bloodshot eyes, dilated or constricted pupils indicate recent drug use
• Track marks or injection sites may be visible on arms or legs
• Frequent nosebleeds can result from intranasal drug administration
• Dental problems (meth mouth) occur with prolonged stimulant abuse

Behavioral and Psychological Changes

• Increased secrecy and social withdrawal from family and friends
• Financial problems due to spending money on drugs
• Neglect of responsibilities at work, school, or home
• Mood swings, irritability, anxiety, or depression become more frequent
• Paranoia or psychotic symptoms may emerge with certain substances
• Loss of interest in previously enjoyed activities (anhedonia)
• Impaired cognitive function affects memory, attention, and decision-making

Drug-Seeking and Use Patterns

• Preoccupation with obtaining and using drugs becomes primary focus
• Doctor shopping to obtain multiple prescriptions for controlled substances
• Using medications in ways other than prescribed (crushing, snorting, injecting)
• Stealing or borrowing medications from others
• Continued use despite negative consequences (health, legal, relationship issues)
• Inability to cut down or control substance use despite attempts
• Experiencing withdrawal symptoms when attempting to stop or reduce use

Treatments for drug addiction

Pharmacological Interventions

• Agonist therapies (methadone) activate opioid receptors to reduce cravings
• Partial agonists (buprenorphine) provide limited opioid effects with lower abuse potential
• Antagonists (naltrexone) block opioid receptors preventing reinforcing effects
• Acamprosate reduces alcohol cravings by modulating glutamate and GABA systems
• Disulfiram causes unpleasant reaction when alcohol is consumed as deterrent
• Nicotine replacement therapy (patches, gum) eases withdrawal from tobacco
• Varenicline acts as partial agonist at nicotinic receptors to reduce smoking urges

Behavioral and Psychosocial Approaches

• Cognitive-behavioral therapy (CBT) addresses drug-related thoughts and behaviors
• Motivational interviewing enhances intrinsic motivation for change
• Contingency management uses positive reinforcement to encourage abstinence
• Mindfulness-based relapse prevention integrates meditation practices
• Family therapy improves communication and support systems
• 12-step facilitation therapy connects individuals with peer support groups
• Dialectical behavior therapy (DBT) teaches emotional regulation and distress tolerance

Integrated Treatment Models

• Medication-assisted treatment (MAT) combines pharmacotherapy with behavioral interventions
• Dual diagnosis treatment addresses co-occurring mental health and substance use disorders
• Therapeutic communities provide long-term residential treatment and social support
• Intensive outpatient programs (IOP) offer structured treatment while living at home
• Harm reduction approaches focus on minimizing negative consequences of drug use
• Telemedicine and mobile health applications expand access to addiction treatment
• Recovery-oriented systems of care provide comprehensive, person-centered support