A balanced evaluation of the evidence for adult neurogenesis in humans: implication for neuropsychiatric disorders
There is a widespread belief that neurogenesis exists in adult human brain, especially in the dentate gyrus, and it is to be maintained and, if possible, augmented with different stimuli including exercise and certain drugs. Here, we examine the evidence for adult human neurogenesis and note important limitations of the methodologies used to study it. A balanced review of the literature and evaluation of the data indicate that adult neurogenesis in human brain is improbable. In fact, in several high-quality recent studies in adult human brain, unlike in adult brains of other species, neurogenesis was not detectable. These findings suggest that the human brain requires a permanent set of neurons to maintain acquired knowledge for decades, which is essential for complex high cognitive functions unique to humans. Thus, stimulation and/or injection of neural stem cells into human brains may not only disrupt brain homeostatic systems, but also disturb normal neuronal circuits. We propose that the focus of research should be the preservation of brain neurons by prevention of damage, not replacement.
KeywordsAdult neurogenesis Neural stem cells Memory Bromodeoxyuridine Homeostasis Neuronal protection DNA repair/methylation
Blood–cerebrospinal fluid barrier
Neural stem cell
Substantia nigra pars compacta
Ventricular zone–subventricular zone
The authors wish to thank Michiko Spector for her valuable contribution in the preparation of this manuscript. This work has been made in part possible by MacBrainResource.
NIMH R01-MH113257 to AD.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
The author declares that the manuscript is in complete compliance with the ethical standards of Brain Structure and Function.
Ethical approval and inform consent
This is a review article and no procedures of any kind were performed on any animals or humans by the authors themselves. This review article is in accordance with general ethical standards of scientific conduct and scientific writing.
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