Last In, First Out: Does Language Loss Reverse First Language Acquisition?

Neurobiological studies have revealed that Alzheimer’s Disease (AD), a leading cause of a global rise in dementia, may develop silently for years, even decades, before it is clearly manifested and clinically diagnosed. Because there are currently no cures or effective treatments for AD, researchers are urgently attempting to investigate prodromal periods of AD, in the hopes of developing drugs or behavioral treatments that may halt disease development. Biomarkers alone cannot definitively identify precursors to dementia and behavioral changes in early disease progression may be subtle and difficult to identify and study. Deficits in memory may occur in prodromal AD; but it is often difficult to determine when these changes are distinguished from those in normal healthy aging. In our work, we investigate whether there are also changes in language which may occur very early. Can subtle changes in language distinguish individuals most susceptible to prodromal AD from those who are aging normally?

This presentation will highlight selected results from a cross-institutional interdisciplinary program of research which evaluates language in Mild Cognitive Impairment (MCI), a known precursor to AD, comparing this language to that of healthy aging (aged 60 to 88 years) and healthy young adults (aged 20-29). This program also compares the language in MCI to language of young children acquiring their first language, and evaluates a ‘regression hypothesis’ which proposes that language abilities acquired later in childhood are the same ones that are lost first in prodromal AD.

Research results do not confirm a regression hypothesis. Rather they suggest that language degeneration in MCI is distinguished from that in Healthy Aging and Healthy Young individuals. Initial pilot results from analyses of brain scan data suggest that new findings of language degeneration cohere with new models of brain connectivity exemplifying a language network.

Results advance new methodology for clinical language analyses in prodromal and early dementia through study of individual’s production of language. They motivate strengthening funding policies which support cognitive behavioral research in prodromal AD in alignment with drug testing/biochemical testing. They have practical implications for how changes in language may impact language comprehension and expression in early stages of dementia.