John Gray discusses his book: Venus on fire, Mars on ice. It’s also a short and uncomplicated introduction to the effects of stress on different diseases and the difference between men and women on a hormonal level with consequences for the stress response. Very clear although somewhat simplified presentation about these matters.
Stressed? Take a few minutes to watch this musical rendition of Robert Sapolsky’s book, Why Zebras Don’t Get Ulcers. The video is the latest creation from Tom McFadden, and his last as a Stanford human biology teaching assistant. McFadden has recently moved on to New Zealand, where he is studying science communication as a Rhodes Fulbright scholar.
At first Dr Shock was baffled. Mixing precious chocolate with chemicals? What a waste. Apparently cocoa has about 52 mg of GABA per 100 gram cacao. GABA is the major inhibitory neurotransmitter in the brain and it has been shown to have an acute psychological stress-reducing effect in humans and a tranquilizing effect on sleeplessness, depression and autonomic disorder observed during the menopausal or presenile period. Because cacao is mixed with milk, sugar and some other ingredients the quantity if GABA in chocolate is less than in cacao, possibly reducing the stress reducing effects in human.
In a recent study, they enriched chocolate with GABA and did a placebo controlled crossover trial to the effect of GABA enriched chocolate on psychological stress. Stress was induced by a arithmetic task and they measured heart rate variability and cortisol concentration in saliva to measure psychological stress.
Chocolate enriched with GABA (GABA chocolate) was composed of 38.5% sugar, 7.8% defatted cacao, 29.8% fat, and 0.28% GABA.
The cortisol, one of our stress hormones didn’t increase after the task in the GABA sessions and those taking the GABA chocolate made a quick recovery in heart rate variability to the normal state from the stressful state. GABA doesn’t permeate the blood-brain barrier, so it’s positive effects on stress in this trial as well as in others has to be explained by it’s effects on the peripheral nervous system.
Based on this study chocolate enriched with GABA had a psychological stress-reducing effect, but does it still taste the same? May be chocolate with Jack Daniels is a better option
Nakamura, H., Takishima, T., Kometani, T., & Yokogoshi, H. (2009). Psychological stress-reducing effect of chocolate enriched with γ-aminobutyric acid (GABA) in humans: assessment of stress using heart rate variability and salivary chromogranin A International Journal of Food Sciences and Nutrition, 60 (s5), 106-113 DOI: 10.1080/09637480802558508
We used to believe that brain tissue couldn’t regenerate, couldn’t grow only prenatal and during early postnatal development. Since than neurogenesis or the process creation of new neurons (nerve cells) has been demonstrated in vitro and vivo experiments and animal research.
It has also been shown that this neurogenesis has an age-related decline from preadolescence (8–10 years old) to adulthood (30–35 years old) in humans.
A brain region that supports neurogenesis is classified as neurogenic. Neurogenic implies the presence of immature precursor cells and a microenvironment that is permissive for the production of new neurons. In the adult mammalian brain, there are two neurogenic regions that are generally accepted, the olfactory system and the hippocampus
What relates adult neurogenesis in the hippocampus to depression?
- The neurogenic hypothesis postulates that a reduced production of new neurons in the hippocampus relates to the pathogenesis of depression and that successful antidepressant treatment requires an enhancement in hippocampal neurogenesis
- Preclinical evidence has shown that stress suppresses hippocampal neurogenesis
- Clinically, stressful life events are known to precipitate depression in vulnerable individuals
- About half of the patients suffering from depression have dysregulation of the HPA system of which the hippocampus is an important part
- Most antidepressant treatments elevate hippocampal neurogenesis only following chronic administration, which parallels the time-course of the emergence of clinical therapeutic effects
- Impaired declarative learning and memory and diminished cognitive flexibility is apparent in patients suffering from depression
- Magnetic resonance imaging showed that depressed individuals have reduced hippocampal volume with the magnitude of the atrophy related to the frequency of the depressive episodes and the duration for which the depression went untreated
- Although hippocampal neurogenesis might not be involved in the pathogenesis of depression, it might be important for some of the therapeutic effects of antidepressant treatments
- The several week delay in the therapeutic onset of antidepressant treatment coincides with the maturation time of newly born hippocampal neurons and that is one reason for believing that adult hippocampal neurogenesis is a possible substrate for the actions of antidepressants
- Other treatments that have antidepressant effect, such as exercise and environmental enrichment, also increase hippocampal neurogenesis
- Antidepressant treatments blocked the reductions in hippocampal neurogenesis caused by stress
The authors of this extensive review summarize the neurogenesis of hippocampus on a cell level as:
Neurogenesis could serve to increase the number of dentate granule cells, provide a reservoir of highly plastic immature neurons, generate multiple cell types, and/or drive the turnover and replacement of mature granule cells The role adult neurogenesis plays in hippocampal function and disease etiology will begin to be more understood as more selective, inducible, and reversible manipulations of in vivo neurogenesis are developed. The discovery of novel therapeutic compounds for various diseases may involve mechanisms that induce a superior regulation of adult hippocampal neurogenesis
The key question is how changes in neurogenesis may be translated into changes in affective behavior that could be beneficial in treating depression.
Darrick T. Balu, Irwin Lucki (2009). Adult hippocampal neurogenesis: Regulation, functional implications, and contribution to disease pathology Neuroscience & Biobehavioral Reviews, 33 (3), 232-252 DOI: 10.1016/j.neubiorev.2008.08.007