Down Syndrome

Often parents and other caregivers seek consultation from diagnosticians related to early onset dementia when an adult in his or her teens or 20s begins to show significant decline in function and behavior (such as mood changes), and cognition. The behavioral changes often manifest in changes in motor skills, unusual movements, changes in speech capabilities, and problems with oral intake.

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As these symptoms often mimic those seen in adults with Down syndrome in their 50s or 60s, they are often misdiagnosed as related to Alzheimer's disease. 

 

Clinicians are now noting that this phenomenon in young adults with Down syndrome is not a form of early-onset Alzheimer's disease, but a heretofore previously undefined brain neuropathology. Generally, this condition has been termed a form of 'regression', but is now known clinically as 'Down syndrome disintegrative disorder' or DSDD -- among other terms. Core features include regression in adaptive function (such as changes in functional activities of daily living [ADLs], speech, and social skills), cognitive–executive function (such as functional skills, declarative memory, procedural memory, learning memory, planning/organizing, and attention), and motor control (such as stereotyped movements, extrapyramidal, initiation–motivation, and catatonia).

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A working group of the US Down Syndrome Medical Interest Group (DSMIG-USA) charged with examining the science and clinical aspects of this condition published an article in Genetics in Medicine. In its 2019 paper, they refer to this condition via a clinically descriptive term -- “Unexplained Regression in Down Syndrome” (URDS). Other groups have also explored this condition and some of their reports are noted below under Down Syndrome "Regression" Resources.