Paleoneurology: neurodegenerative diseases are age-related diseases of specific brain regions recently developed by Homo sapiens.
Bipedal locomotion and fine motility of hand and larynx of humans introduced musculoskeletal adaptations, new pyramidal, corticostriatal, corticobulbar, nigrostriatal, and cerebellar pathways and expansions of prefrontal, cingular, parieto-temporal and occipital cortices with derived new brain capabilities. All selectively degenerate in aged homo sapiens following 16 syndromic presentations: (1) Parkinsonism: nigrostriatal control for fast automatic movements of hand, larynx, bipedal posture and gait ("simian gait and hand"). (2) Frontal (highest level) gait disorders (lower body parkinsonism, gait apraxia, retropulsion): prefrontostriatal executive control of bipedal locomotion. (3) ataxia: new synergistic coordination of bipedal gait and fine motility. (4) Dyskinesias (chorea, dystonia, tremor...): intrusions of simian basal ganglia motor subroutines. (5) motoneuron diseases: new proximo-distal and bulbar motoneurones, preserving older ones (oculomotor, abdominal...). (6) Archaic reflexes: prefrontal disinhibition of old mother/tree-climbing-oriented reflexes (sucking, grasping, Babinski/triple retraction, gegenhalten), group alarms (laughter, crying, yawning, grunting...) or grooming (tremor=scratching). (7) Dysautonomia: contextual regulation (orthostatism...). (8) REM sleep disorders of new cortical functions. (9) Corticobasal syndrome: melokinetic control of hand prehension-manipulation and language (retrocession to simian patterns). (10) Frontal/temporal lobe degeneration: medial-orbitofrontal behavioural variant: self monitoring of internal needs and social context: apathy, loss of personal hygiene, stereotypia, disinhibition, loss of concern for consequences of acts, social rules, danger and empathy; dorsolateral executive variant: inadequacy to the context of action (goal, environmental changes...); progressive non-fluent aphasia: executive and praxic processing of speech; temporal variant: abstract concepts for speech, gestures and vision (semantic dementia, progressive nonfluent aphasia) (11) Temporomesial-limbic-paralimbic-associative cortical dementias (Alzheimer's disease, Lewy body, progressive amnesia): processing of explicit cognition: amnesic syndrome, processing of hand, larynx and eye: disorientation, ideomotor apraxia, agnosia, visuospatial processing, transcortical aphasia. (12) Focal posterior atrophy (Benson, progressive apraxia): visuomotor processing of what and where. (13) Macular degeneration: retinal "spot" for explicit symbols. (14) "Psychiatric syndromes": metacognition, self monitoring and regulation of hierarchical processing of metacognition: hallucinations, delusions, magic and mystic logic, delusions, confabulations; drive: impulsivity, obsessive-compulsive disorders, mental automatisms; social interactions: theory of mind, autism, Asperger. (15) Mood disorders: control on emotions: anxio-depressive and bipolar disorders, moria, emotional lability. (16) Musculoskeletal: inclusion body myositis: muscles for bipedal gait and fine motility. Paget's disease: bones for bipedal gait and cranium. Understanding of the genetic mechanisms underlying the evolution of these recent human brain regions and paleoneurology my be the key to the focal, asymmetrical or systemic character of neurodegeneration, the pathologic heterogeneity/overlap of syndromic presentations associating gait, hand, language, cognition, mood and behaviour disorders.
Ghika
J
J
CHCVs, Division of Neurology, Avenue Grand Champsec 80, CH-1951 Sion (VS), Switzerland. joseph.ghika@rsv-gnw.ch
D000375:Aging; D001519:Behavior; D005075:Biological Evolution; D001921:Brain / Q000033:anatomy & histology* / Q000473:pathology; D001927:Brain Diseases / Q000473:pathology; D001931:Brain Mapping; D006801:Humans; D008954:Models, Biological; D008962:Models, Theoretical; D019636:Neurodegenerative Diseases / Q000628:therapy*; D009462:Neurology / Q000379:methods*; D010164:Paleopathology / Q000379:methods