Primitive reflexes in Down's syndrome

The clinical value and prevalences of three primitive reflexes, i.e. the palmomental, the snout, and the corneomandibular, were examined in 30 institutionalized patients with Down's syndrome and the results were compared with those in a control group. The prevalence of palmomental reflex was clearly higher, i.e. 47% (31,63) in DS as compared to 7% (2,16) in controls (confidence limits, P = 0.9, is given in the parenthesis) (P = 0.0001). The prevalences of the snout reflex in the DS and control group were estimated to be 14% (5,29) and 0% (0,6) respectively (P = 0.02). The corneomandibular reflex was found unreliable in DS, mainly because of lack of cooperation. Neither the palmomental nor the snout reflex correlated well with the degree of mental retardation. No correlation of reflex incidence with age was demonstrated for the palmomental reflex. The prevalence of the snout reflex in DS patients less than 35 years was estimated to be 0% (0,18). This is significantly (P less than 0.05) less than the prevalence of 29% (10,54), found in the group older than 35 years of age. The possible value of the snout reflex as a sign of dementia in Down's syndrome is discussed.