Altered tonic and phasic cortisol secretion following unilateral stroke

Area of Science:

• Neuroscience
• Endocrinology
• Psychology

Background:

• Cerebral laterality, particularly right hemisphere involvement, is implicated in stress response regulation via the hypothalamic-pituitary-adrenal (HPA) axis.
• Previous research on brain-damaged patients has yielded inconsistent findings regarding laterality effects on cortisol secretion.

Purpose of the Study:

• To investigate if unilateral stroke differentially impacts tonic and phasic HPA axis responses.
• To assess the influence of lesion location within the hemisphere on HPA axis regulation.

Main Methods:

• Examined basal morning cortisol levels and cortisol reactivity to a mental stressor in 32 stroke patients (18 left-hemisphere, 14 right-hemisphere) and 30 healthy controls.
• Compared cortisol secretion patterns between patient groups and controls, analyzing lesion location effects.

Main Results:

• Left-hemisphere stroke patients showed elevated morning cortisol compared to controls; right-hemisphere patients did not.
• Phasic cortisol responses to stress were blunted in stroke patients overall, most notably in right-hemisphere patients.
• Anterior lesions correlated with reduced phasic cortisol responses, particularly in right-hemisphere stroke patients.

Conclusions:

• Findings support the hypothesis of right hemisphere excitatory control over cortisol secretion and asymmetrical stress response regulation.
• Left- and right-sided strokes differentially affect HPA axis response patterns, highlighting the role of hemispheric specialization in stress management.