New Brain Cells
In the last decade it has become clear that new cells can form in the adult brain. This happens in a region known as the hippocampal complex. The hippocampal complex is found deep inside either temple and is crucial for memory and emotion. The hippocampal complex inhibits the human stress response, but can itself be damaged by persistent stress, leading to a vicious cycle in which the stress response is amplified further and depression ensues.
Experimental work suggests that neurogenesis (the birth of new neurons) in the hippocampal complex is vital for the action of conventional antidepressant drugs. Exercise and enriched environments also promote neurogenesis, whilst stress has the opposite effect.The current picture is that hippocampal health (including the birth of new neurons) is essential for protecting the organism against the effects of stress, so that if hippocampal functioning is compromised, anxiety and depression can emerge.
There has been recent interest in the antidepressant properties of a natural molecule called curcumin. This substance is found in the herb turmeric. As well as a foodstuff, turmeric has been used for centuries in traditional Indian medicine (Ayurveda). In pre-clinical studies, curcumin exhibited clear antidepressant effects.
Research has focused on the mechanism of action of curcumin. Remarkably it appears that curcumin can also increase the birth of new neurons in the hippocampal complex. This is an intriguing finding which hints at the possibility of a new class of antidepressant drug.
A new paper from researchers at King's College London provides an excellent summary of work in this area. The full paper can be read here.