Cognitive aspects of Down syndrome across the lifespan Dr Gaye Powell Head of Speech & Language Services Plymouth Teaching PCT ( DDREG member)
Down syndrome Profiles Plateaus Prophecies And Why the interest?
lifespan expectancy (reproduced from Glasson and Bittles, 2004) Table I: Life expectancies of individuals with Down syndrome, from selected population-based studies Year of publication Average life expectancy (y) Country 1929,1949 9, 12 England 26 1963 18 Australia 79 1973 30 USA 80 1982 35 Transnational* 35 1991 56 USA 81 2002 60 Australia 27 * Australian, US, Canadian, and European estimates Reference
Lifespan (reproduced from Glasson and Bittles, 2004)
Profiles Models: genetic, medical, neurobiological, psychological and developmental Are findings from early intervention valid? (Wishart, 1996) Variables of better medical care and general health, a home environment and access to educational toys and stimulation Influence of gender
Infancy early gains between 1.5 months and 6 months (Carr, 1988) in line with TD children in contingency learning 6 months (Ohr and Fagen 1991, 1993) then decline (Ohr and Fagen 1994) steep drop in IQ between 1 and 3 years up to 13 years (Carr review 1985; Wishart & Duffy, 1990; Wishart 1995)
Efficacy of early intervention? effects upon cognition relatively short lived (Hines & Bennett, 1996; Spiker & Hopman 1997) display greater decline in cognitive scores than children with Autism, or developmental delay after 8 years (Sigman & Ruskin 1999) Launonen (1996, 1998, 2003) highlighted impact of early manual signing
Why? processes involved in acquisition and maintenance 3 neurobehavioral phenotypes (Capone 2004) 1. no spoken language despite adequate cognitive skills and language comprehension 2. PDD + history of regression, in addition to cognitive and speech difficulties 3. those who do progress - intact neural machinery to process, organize, store and recall
Programmes to match deficit profile? Launonen (1996, 1998, 2003) early signing group advanced on all measures (social, academic,cognitive) at all points up to 8yrs compared to controls shared attention, reciprocal and active engagement in interaction, symbolic representation, and initiation of interactions
delay versus difference difference strengths - social and visuo-spatial skills difficulties - verbal-linguistic development, auditory processing (Bellugi, 1994; Chapman, Seung, Schwartz and Kay-Raining Bird, 1998; Fowler, 1990; Hodapp, 1996) delay sequence of acquisition are in line (Fowler, Gelman and Gleitman, 1994)
Late childhood and Adolescence
What changes? No significant change (Carr 2000) language ability not always appear to be directly related to nonverbal IQ (Rondal, 1995) reading and language bootstrap other areas (Buckley et al 1996; Carr 2000) educational inclusion for adolescents gains communication & academic skills (Cunningham et al 1998).
Adulthood
Dementia a reality? neuropathology associated with AD at risk (Wisneiwski, Wisneiwski and Wen, 1985) biological age exceeds CA up to 20 years (Olson and Shaw, 1969) However, majority of individuals do not exhibit clinical signs (see Silverman et al, 1998; Devenny et al 1992; Burt et al 1995 )
Plateaus Anecdotal - develop more slowly, longer periods of consolidation plateauing between developmental spurts How do children learn, develop and fail to retain skills? (Wishart,1990, 1991, 1993a, 1993b ; Wishart & Duffy 1990) Reliability of responses? Lack of engagement, motivation, avoidance behaviours.
Influencing factors (Wishart 1996) early experiences of failure lower expectations of carers the use of avoidance strategies when faced with cognitive challenges poor use of existing problem solving skills failure to assimilate & consolidate newly-acquired cognitive skills increasing reluctance to take the initiative learning process
Plateau due to genetic predisposition and programming neurophysiology health psychological environmental factors some skills acquired greater difference over time
Prophecies for 21 st century?
Programmes of intervention? truly effective programmes of intervention? exploiting areas of strength visual channel signing, reading systems learning environments continued intervention to protect vulnerable areas integration of pharmacological treatments
Significant impact on cognitive profile? integration of methodologies and packages of care With individuals & families at centre of the process