Neurobiology of Addiction and Mental Health

Flashcards defining key vocabulary terms, mechanisms, and physiological concepts from the lecture on the neurobiology of addiction, neurotransmitters, alcohol abuse, nicotine, opioids, cocaine, depression, and behavioral addictions.

Excitatory Neurotransmitters

Neurotransmitters such as Acetylcholine, Glutamate, and Dopamine that increase the likelihood that a post-synaptic neuron will fire an action potential.

Inhibitory Neurotransmitters

Neurotransmitters such as Serotonin and GABA that decrease the likelihood that a post-synaptic neuron will fire an action potential.

Adrenergic Receptors

Receptors that bind catecholamines (adrenaline, epinephrine, and noradrenaline/norepinephrine) to mediate sympathetic nervous system functions, such as increasing heart rate, muscle contraction, bronchodilation, blood pressure, and automatic fight-or-flight responses.

GABA (Gamma-Aminobutyric Acid)

The primary inhibitory neurotransmitter in the brain that regulates neuronal excitability, promotes sleep, and maintains balanced signaling with glutamate in the hippocampus for learning and memory.

Limbic System

The emotional and behavioral center of the brain that acts as the addiction and reward headquarters, comprising the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus.

Amygdala

A major emotion and reward center located within the limbic system of the brain.

Hippocampus

A limbic brain structure essential for encoding new memories about past experiences and regulating memory consolidation during sleep.

Nucleus Accumbens

A region within the limbic system strongly associated with motivation, pleasure, and reward processing.

Brain Reward Circuitry

An evolutionary neural pathway innervated by dopamine-producing neurons in the ventral tegmental area (VTA) that project to the nucleus accumbens, amygdala, hippocampus, and prefrontal cortex to mediate responses to natural and artificial rewards.

Addiction

A chronic brain disease characterized by compulsive and uncontrollable substance use or behavior despite negative consequences, driven by neurochemical changes in the brain's reward system.

Tolerance

A state developing over repeated substance exposure where the body requires increased amounts of an addictive substance or behavior to achieve the initial effect.

Two-Hit Theory of Addiction

A vulnerability model stating that two distinct hits—such as genetic susceptibility or early adversity (hit 1) combined with drug exposure or environmental stress (hit 2)—are required to trigger substance use disorder.

Epigenetics

Acquired or inherited modifications that alter gene expression and cellular function without altering the underlying DNA sequence.

Cocaine

A potent central nervous system stimulant that crosses the blood-brain barrier and blocks dopamine transporters, preventing dopamine reuptake and producing excess synaptic dopamine levels.

Opioids

Substances (such as morphine, heroin, fentanyl, oxycodone, and codeine) that bind to opioid receptors to produce analgesia, sedation, and euphoria while suppressing natural endorphin production.

Opioid Mechanism of Action

The interaction where opioids bind to opioid receptors, triggering excessive stimulation of the dopamine reward system while downregulating endogenous endorphin production.

Naltrexone

A non-controlled opioid antagonist that blocks opioid receptors to prevent euphoric and sedative effects and reduce cravings during long-term addiction treatment.

Naloxone (Narcan)

A rapid-acting opioid receptor antagonist used in emergency situations to displace opioids like fentanyl, heroin, and oxycodone to reverse acute overdose.

Nicotine

The chief addictive chemical in tobacco that stimulates nicotinic acetylcholine receptors, triggering adrenaline release and activating the dopamine reward system within 10 seconds of inhalation.

Nicotinic Acetylcholine Receptors (nAChRs)

A family of receptor binding sites in the nervous and muscular systems activated by acetylcholine and nicotine, involved in cognitive functions, memory, and dopamine release.

Bronchiolitis Obliterans (Popcorn Lungs)

A condition damaging the smallest lung airways and causing coughing and shortness of breath, associated with vaping-induced changes in lung tissue permeability.

Alcohol Use Disorder (AUD)

A chronic disease characterized by an inability to control drinking due to physical and emotional dependence on alcohol.

Alcohol Withdrawal Syndromes

A spectrum of symptoms occurring upon cessation of chronic alcohol use, ranging from minor tremors, irritability, and insomnia to severe hallucinosis, confusion, and life-threatening seizures (DTs).

Alcoholic Hepatitis

Inflammation of the liver occurring in up to $35\text{\%}$ of heavy drinkers, presenting with jaundice, fatigue, low-grade fever, nausea, vomiting, right upper abdominal tenderness, and weight loss.

Major Depressive Episode

A period of serious mood impairment involving decreased levels of serotonin, dopamine, and norepinephrine, affecting mood, motivation, energy, and concentration.

HPA Axis (Hypothalamic-Pituitary-Adrenal Axis)

The body's primary neuroendocrine stress response system consisting of the pathway: $\text{Stress} \rightarrow \text{Hypothalamus} \rightarrow \text{CRH} \rightarrow \text{Pituitary} \rightarrow \text{ACTH} \rightarrow \text{Adrenal glands} \rightarrow \text{Cortisol}$.

Cortisol

A primary glucocorticoid stress hormone produced by the adrenal glands that regulates gluconeogenesis, metabolism, inflammation, blood pressure sensitivity, and circadian rhythm.

Selective Serotonin Reuptake Inhibitors (SSRIs)

Antidepressants that block the serotonin transporter (SERT) to increase synaptic serotonin levels, leading to downstream neuroplastic adaptations in neural circuits over time.

Postpartum Depression (PPD)

A severe medical condition following childbirth driven by rapid drops in estrogen and progesterone, altered HPA axis stress responses, sleep deprivation, and monoamine neurochemical changes.

Variable Reinforcement Schedule

An unpredictable reward pattern (variable-ratio/variable-interval) that generates reward prediction errors, driving cue-driven habit loops in behaviors like social media checking and online gambling.

Problematic Pornography Use (PPU)

A condition categorized under Compulsive Sexual Behavior Disorder involving persistent cravings, tolerance, rewiring of reward circuits, and disruption of real-life intimacy.