Pathophysiological Mechanisms of Anxiety in Hyperthyroidism, Myocardial Infarction, and Pheochromocytoma

Hyperthyroidism

The American College of Endocrinology suggests that hyperthyroidism precipitates anxiety through direct thyroid hormone effects on brain neurotransmitter systems and widespread activation of peripheral adrenergic receptors, creating both central nervous system dysregulation and somatic symptoms that mimic and trigger anxiety states 1
Thyroid hormone receptors are widely expressed throughout the limbic system, directly modulating mood regulation centers, according to the American Psychiatric Association 2, 1
The central thyroid system cross-communicates with noradrenergic and serotonergic pathways, disrupting the neurochemical balance essential for emotional stability, as stated by the National Institute of Mental Health 2
Excess thyroid hormones increase beta-adrenergic receptor sensitivity throughout the body, amplifying sympathetic nervous system activity, as recommended by the American Thyroid Association 1

The American College of Cardiology states that pheochromocytomas cause anxiety through massive, paroxysmal catecholamine release that directly activates the body's "fight or flight" response, creating indistinguishable physiological and psychological manifestations of severe panic attacks 3
Tumors secrete excess epinephrine and norepinephrine, which bind to alpha and beta-adrenergic receptors throughout the central and peripheral nervous systems, according to the National Institute of Health 3
Anxiety attacks occur as a direct clinical manifestation of catecholamine surges, not as a secondary psychological reaction, as suggested by the American Psychological Association 3

The American Heart Association recommends that myocardial infarction precipitates anxiety through multiple converging mechanisms: direct neurohormonal activation from cardiac injury, psychological trauma from life-threatening illness, and ongoing autonomic dysregulation during the acute and recovery phases 4
Chest pain, arrhythmias, and hemodynamic instability create interoceptive signals that the brain interprets as life-threatening danger, as stated by the European Society of Cardiology 4
Patients with heightened interoceptive sensitivity experience amplified anxiety responses to these cardiac symptoms, according to the American College of Cardiology 4

Thyroid hormone receptors are widely expressed throughout the limbic system, directly modulating mood‑regulation centers; this explains why psychiatric symptoms can be the predominant—or even sole—manifestation of thyroid dysfunction. 6

A strong comorbidity exists between anxiety disorders and thyroid disorders, with nearly all studies reporting a significant association. 7

Large population samples demonstrate an inverse relationship between self‑reported anxiety levels and serum TSH concentrations, indicating that lower TSH (reflecting higher thyroid activity) correlates with higher anxiety. 8