From the Guidelines
When compared to the nervous system, hormones have a slower onset of action but typically produce longer-lasting effects. Hormones are chemical messengers released by endocrine glands into the bloodstream, traveling throughout the body to reach target cells with specific receptors, as noted in a study published in 2015 1. Unlike the rapid electrical impulses of the nervous system which act within milliseconds, hormonal responses generally take minutes to hours to develop. Hormones also tend to affect multiple tissues simultaneously rather than targeting specific locations as neural signals do. Additionally, hormonal effects are more diffuse and widespread, regulating processes like metabolism, growth, reproduction, and stress responses over extended periods. The endocrine system works complementary to the nervous system, with hormones often maintaining homeostasis and mediating longer-term physiological changes while the nervous system handles immediate responses to stimuli.
Some key points to consider about hormones and their effects on the body include:
- Hormones act at low circulating concentrations and often exhibit non-linear and non-monotonic dose responses, as discussed in a study from 2015 1.
- The effects of hormones differ based on an individual’s stage of development, highlighting the complexity of hormonal regulation in the body.
- Stress hormones, such as those of the hypothalamic-pituitary-adrenal (HPA) axis, have been implicated in various physiological and psychological processes, including depression and anxiety, as explored in studies from 2015 1 and 2018 1.
- The hypothalamic-pituitary-thyroid (HPT) axis has also been linked to anxiety disorders, with findings suggesting subtle thyroid dysfunction in individuals with anxiety, as reported in a systematic review from 2018 1.
Overall, the differences in timing and scope between the endocrine and nervous systems allow these two regulatory systems to coordinate body functions across different timeframes, ensuring the maintenance of homeostasis and the regulation of various physiological processes. The most recent and highest quality study, from 2018 1, supports the importance of considering hormonal effects in the context of anxiety disorders and other physiological processes.
From the Research
Comparison of Hormones and the Nervous System
- Hormones have a significant impact on the nervous system, particularly in relation to mood disorders and depression 2, 3.
- The fluctuation of gonadal steroids, such as estrogen and progesterone, can affect the onset and course of depressive symptoms in women 2.
- Hormonal changes during the menopausal transition can lead to mood swings, depressive symptoms, anxiety, and sleeping disorders 3.
- The serotonergic system, which is influenced by sex hormones, plays a crucial role in the pathogenesis of anxiety disorders and major depression 3.
Hormone Replacement Therapy and Depression
- Hormone replacement therapy (HRT) has been shown to be effective in treating depression in perimenopausal women, particularly when estrogen is delivered through a skin patch 4.
- HRT can stabilize hormone levels, which may help to alleviate depressive symptoms in women during the menopausal transition 4.
- The combination of HRT and fluoxetine has been found to be more effective than HRT alone in treating menopausal depression, with a satisfactory safety profile 5.
Stress and Hormones
- The stress system, which is mediated by corticotropin-releasing hormone (CRH) and corticosteroid hormones, plays a crucial role in the body's response to stress 6.
- Imbalance in the stress system, induced by genetic modification or chronic stressors, can lead to changes in neural signaling pathways underlying psychic domains of cognition and emotion, anxiety, and aggression 6.