Table of Contents

Neurotransmitters and Associated Conditions

Neurotransmitters are chemical messengers that facilitate communication between neurons. Imbalances in their levels can contribute to various neurological and psychological conditions. Below is an overview of key neurotransmitters and conditions linked to their dysregulation.

Serotonin (5-HT)

Function: Regulates mood, appetite, sleep, and cognitive processing.

  1. Low Levels:
    • Depression
    • Anxiety disorders
    • Obsessive-Compulsive Disorder (OCD)
    • Insomnia
  2. High Levels:
    • Serotonin syndrome (agitation, hyperthermia)
    • May contribute to mania in bipolar disorder

Dopamine

Function: Controls reward, motivation, movement, and emotional responses.

  1. Low Levels:
    • Parkinson’s disease (motor symptoms)
    • Depression
    • ADHD (dysregulation)
  2. High Levels:
    • Schizophrenia (excess in mesolimbic pathway)
    • Addiction
    • Mania

Norepinephrine (Noradrenaline)

Function: Modulates alertness, arousal, and the “fight-or-flight” response.

  1. Low Levels:
    • Depression
    • ADHD
    • Fatigue
  2. High Levels:
    • Anxiety disorders
    • Hypertension
    • PTSD (hyperarousal)

GABA (Gamma-aminobutyric Acid)

Function: Primary inhibitory neurotransmitter; reduces neuronal excitability.

  1. Low Levels:
    • Anxiety disorders
    • Epilepsy
    • Insomnia
  2. High Levels:
    • Sedation (e.g., from benzodiazepines)
    • Respiratory depression (overdose)

Glutamate

Function: Primary excitatory neurotransmitter; involved in learning and memory.

  1. Low Levels:
    • Rare; may impair cognition
  2. High Levels:
    • Excitotoxicity (stroke, traumatic brain injury)
    • Neurodegenerative diseases (Alzheimer’s, ALS)

Acetylcholine (ACh)

Function: Regulates muscle activation, memory, and attention.

  1. Low Levels:
    • Alzheimer’s disease
    • Myasthenia gravis (receptor dysfunction)
  2. High Levels:
    • Organophosphate poisoning (muscle spasms, seizures)
    • Parkinson’s tremors (in specific pathways)

Endorphins

Function: Natural painkillers; promote pleasure and stress relief.

  1. Low Levels:
    • Chronic pain syndromes
    • Depression
    • Opioid withdrawal
  2. High Levels:
    • “Runner’s high” (exercise-induced)
    • Euphoria (opioid use)

Histamine

Function: Regulates wakefulness, immune response, and allergic reactions.

  1. Low Levels:
    • Sedation (antihistamine side effect)
    • Narcolepsy (possible link)
  2. High Levels:
    • Allergic reactions (hives, anaphylaxis)
    • Insomnia (overactivation)

Summary Table

Neurotransmitter Low Levels Associated With High Levels Associated With
——————-————————————-—————————————
Serotonin Depression, OCD, insomnia Serotonin syndrome, mania
Dopamine Parkinson’s, depression, ADHD Schizophrenia, addiction
Norepinephrine Depression, fatigue Anxiety, hypertension
GABA Anxiety, epilepsy Sedation, respiratory depression
Glutamate Cognitive impairment (rare) Neurodegeneration, excitotoxicity
Acetylcholine Alzheimer’s, myasthenia gravis Poisoning, muscle spasms
Endorphins Chronic pain, depression Euphoria, exercise-induced highs
Histamine Sedation, narcolepsy Allergies, insomnia

Notes

Neurotransmitters as Hormones

Neurotransmitters are primarily known for their role in neuronal communication within the central nervous system (CNS). However, when they are released into the bloodstream or act outside the blood-brain barrier, they can function as hormones, influencing various physiological processes throughout the body.

Norepinephrine:

Dopamine:

Serotonin:

Acetylcholine:

Histamine:

Glutamate and GABA:

Key Points

Example Table

Neurotransmitter CNS Role (Neurotransmitter) Peripheral Role (Hormone)
——————-—————————–—————————————–
Norepinephrine Attention, arousal Fight-or-flight response
Dopamine Reward, movement Kidney function, blood pressure
Serotonin Mood, sleep Gut motility, blood flow
Acetylcholine Memory, learning Heart rate, digestion, muscle control
Histamine Wakefulness, appetite Immune response, inflammation