Neurotransmitter-based diagnosis and treatment: A hypothesis (Part 1)

Dopamine deficiency (Table 2^{4,14,20,38,40-43})

Mr. W experiences widespread pain, including chronic back pain, headaches, and abdominal pain. He also has substantial anhedonia, lack of interest, procrastination, and hypersomnia.^41,42 He is apathetic and has difficulty getting up in the morning.^41,42 Unusual tiredness and weakness drive him to overuse caffeine; he states that 5 Mountain Dews and 4 cups of regular coffee a day make his headaches bearable.^38,41-43 Sex also improves his headaches. Since childhood, he has taken stimulants for attention-deficit/hyperactivity disorder. He reports that occasional use of cocaine helps ease his pain and depression. Mr. W’s wife is concerned with her husband’s low sexual drive and alcohol consumption, and discloses that he has periodic trouble with gambling. Mr. W was forced into psychotherapy but never was able to work productively with his therapist.^38,41-43 He loves eating and cannot control his weight.⁴⁰ This contrasts with episodic anorexia he experienced when he was younger.²⁰ His face is usually emotionless.⁴³ Mr. W is prone to constipation.¹⁴ His restless leg syndrome and periodic limb movement disorder are so bad that his wife refuses to share a bed with him.¹⁴ He is clumsy and has a problem with repetitive motor tasks.⁴³ A paucity of speech, limited eye contact, poor grooming, and difficulty forming therapeutic alliances have long been part of Mr. W’s history.^38,42,43 On physical examination, he has a dry mouth; he is stiff, tremulous, and hypotensive.¹⁴

Impression. Mr. W shows multiple symptoms associated with dopamine deficiency. Bupropion may be reasonable to consider. Dopamine augmentation via the use of stimulants is warranted in such patients, especially if stimulants had not been tried before (lisdexamfetamine would be a good choice to minimize addictive potential). For a patient with dopamine deficiency, levodopa may improve more than just restless legs. Amantadine may improve dopaminergic signaling through the accelerated dopamine release and decrease in presynaptic uptake, so this medication may be carefully tried.⁴⁴ Pain treatment would not be successful for Mr. W without simultaneous treatment for his substance use.

Bottom Line

Both high and low levels of serotonin and dopamine may be associated with certain psychiatric and medical symptoms and disorders. An astute clinician may judge which neurotransmitter is dysfunctional based on the patient’s presentation, and tailor treatment accordingly.

Related Resources

• Abell SR, El-Mallakh RS. Serotonin-mediated anxiety: How to recognize and treat it. Current Psychiatry. 2021;20(11):37-40. doi:10.12788/cp.0168

Drug Brand Names

Amantadine • Gocovri
Baclofen • Ozobax
Bupropion • Wellbutrin
Fluoxetine • Prozac
Lisdexamfetamine • Vyvanse
Paroxetine • Paxil