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Major depressive disorder
Seasonal affective disorder
Premenstrual dysphoric disorder
Generalized anxiety disorder
Social anxiety disorder
Body focused repetitive disorders
Body dysmorphic disorder
Post-traumatic stress disorder
Physical and sexual abuse
Cluster A personality disorders
Cluster B personality disorders
Cluster C personality disorders
Somatic symptom disorder
Alcohol use disorder
Male hypoactive sexual desire disorder
Female sexual interest and arousal disorder
Genito-pelvic pain and penetration disorder
Attention deficit hyperactivity disorder
Disruptive, impulse control, and conduct disorders
Fetal alcohol syndrome
Autism spectrum disorder
Shaken baby syndrome
Neuroleptic malignant syndrome
Mood disorders: Pathology review
Amnesia, dissociative disorders and delirium: Pathology review
Personality disorders: Pathology review
Eating disorders: Pathology review
Psychological sleep disorders: Pathology review
Psychiatric emergencies: Pathology review
Drug misuse, intoxication and withdrawal: Hallucinogens: Pathology review
Malingering, factitious disorders and somatoform disorders: Pathology review
Anxiety disorders, phobias and stress-related disorders: Pathology Review
Trauma- and stress-related disorders: Pathology review
Schizophrenia spectrum disorders: Pathology review
Drug misuse, intoxication and withdrawal: Stimulants: Pathology review
Drug misuse, intoxication and withdrawal: Alcohol: Pathology review
Developmental and learning disorders: Pathology review
Childhood and early-onset psychological disorders: Pathology review
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Tanner Marshall, MS
Jake RyanRishi Desai, MD, MPH
Kelly Mackenzie, MA
Robyn Hughes, MScBMC
Worldwide, opioids are the most common cause of drug related deaths.
The number of individuals who use them has quadrupled in the last 20 years, with an uptick in heroin use, an even bigger uptick in prescription opioid use, and a large number of people using both.
Because of their potential for addiction and overdose, opioids are regulated substances in many countries.
As a class, opioids share one thing in common—they bind to opioid receptors in the brain, spinal cord, and gastrointestinal tract.
Some are endogenous, meaning that they are produced naturally by the body, like endorphin, short for endogenous morphine.
But others are exogenous, meaning that they come from the environment, like heroin and morphine, which come from the opium poppy—a flowering plant that oozes a milky white liquid—while others like fentanyl are synthesized in the laboratory.
To understand how opioids work, let’s zoom into a region of the brain tissue that has opioid receptors.
Normally, in the absence of endorphins, inhibitory neurons secrete a neurotransmitter that prevents nearby neurons from releasing the neurotransmitter dopamine.
Now, let’s say someone goes to play a rigorous game of badminton.
Exercise releases endorphins which activate the three major opioid receptors located on the inhibitory neurons, called the mu, kappa, and delta receptors.
As endorphins bind to these receptors, they block the inhibitory neuron from releasing neurotransmitters, allowing the dopamine secreting neurons to freely unload dopamine.
The dopamine then gets picked up by a third neuron in the same area.
When dopamine release takes place in pain processing regions of the brain like the thalamus, brainstem, and spinal cord, the result is feeling less pain.
Opioid dependence is a medical condition characterized by compulsive use of opioids despite knowing the underlying danger, and developing withdrawal syndrome when opioid use stops. Opioids include drugs like morphine, heroin, codeine, oxycodone, hydrocodone, etc. The treatment for opioid dependence involves a combination of therapy and medications, with support from family and friends.
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