Heiko Braak (born June 16, 1937) is a German anatomist. Braak was born in Kiel, Schleswig-Holstein, and studied medicine at the universities of Hamburg, Berlin, and Kiel. He is Professor at the Institute of Clinical Neuroanatomy, Johann Wolfgang Goethe-University, Frankfurt am Main.
Braak’s early research focused on the morphology of the central nervous system of chondrichthyan fishes. In the holocephalan species Chimaera monstrosa (ratfish), he described, in the basal midline of the diencephalon, a previously unknown ependymal structure adjacent to the rostral part of the optic chiasma referred to as the ‘organon vasculare praeopticum’. It may be considered homologous to the supraoptic crest of mammals. Braak also described the morphology of the neurohypophysial complex of the squaliform elasmobranch Etmopterus spinax (Spinax niger).
Braak’s further research has focused on the morphology and pathoanatomy of the human central nervous system, in particular of the cerebral cortex (1980).
Braak has also contributed extensively to the neuropathology of Alzheimer's disease and Parkinson's disease. In particular, he introduced a classification of Alzheimer’s disease into six distinct pathoanatomical stages, now commonly referred to as Braak stages, based on the topographical distribution pattern of neurofibrillary changes from circumscribed parts of the limbic system to the higher neocortical association fields.* A similar classification was proposed in 2003 for the pathoanatomical changes associated with idiopathic Parkinson's disease.
Recently, Braak and co-authors advanced a ‘dual-hit hypothesis’ about the pathogenesis of idiopathic Parkinson's disease, according to which an unknown pathogen akin to a slow-virus may enter the nervous system through both the nasal and intestinal mucosae, eventually resulting in a cascade of neurodegenerative events in the brain.
Braak is the son of the philologist Professor Ivo Braak (1906–1991) and brother of theatre director Dr. Kai Braak.
- Braak, H. (1963). "Das Ependym der Hirnventrikel von Chimaera monstrosa (mit besonderer Berücksichtigung des Organon vasculare praeopticum)". Zeitschrift für Zellforschung und Mikroskopische Anatomie 60 (4): 582–608. doi:10.1007/BF00331185.
- Kuhlenbeck H. (1977). The central nervous system of vertebrates. Vol. 5, Part I, p. 89. Karger, Basel.
- Braak, H. (1962). "Über die Gestalt des neurosekretorischen Zwischenhirn-Hypophysen-Systems von Spinax niger". Zeitschrift für Zellforschung und Mikroskopische Anatomie 58 (2): 265–276. doi:10.1007/BF00320188.
- Braak H, Braak E (1991). "Neuropathological stageing of Alzheimer-related changes". Acta Neuropathologica 82 (4): 239–259. doi:10.1007/BF00308809. PMID 1759558.
- Braak, H., Del Tredici, K., Rüb, U, de Vos, R.A.I et al. (2004). "Staging of brain pathology related to sporadic Parkinson's disease". Neurobiology of Aging 23: 197–211.
- Braak, H.; Braak, E. (1987). "Argyrophilic grains: characteristic pathology of cerebral cortex in cases of adult onset dementia without Alzheimer changes". Neuroscience Letters 76 (1): 124–127. doi:10.1016/0304-3940(87)90204-7. PMID 2438598.
- Hawkes, C.H.; Del Tredici, K.; Braak, H. (2007). "Review: Parkinson's disease: a dual-hit hypothesis". Neuropathology and Applied Neurobiology 33 (6): 599–614. doi:10.1111/j.1365-2990.2007.00874.x. PMID 17961138.