Longitudinal assessment of dementia measures in Down syndrome

Abstract

Introduction Early detection of dementia symptoms is critical in Down syndrome (DS) but complicated by clinical assessment barriers. The current study aimed to characterize cognitive and behavioral impairment using longitudinal trajectories comparing several measures of cognitive and behavioral functioning. Methods Measures included global cognitive status (Severe Impairment Battery [SIB]), motor praxis (Brief Praxis Test [BPT]), and clinical dementia informant ratings (Dementia Questionnaire for People with Learning Disabilities [DLD]). One‐year reliability was assessed using a two‐way mixed effect, consistency, single measurement intraclass correlation among non‐demented participants. Longitudinal assessment of SIB, BPT, and DLD was completed using linear mixed effect models. Results One‐year reliability (n = 52; 21 male) was moderate for DLD (0.69 to 0.75) and good for SIB (0.87) and BPT (0.80). Longitudinal analysis (n = 72) revealed significant age by diagnosis interactions for SIB (F(2, 115.02) = 6.06, P = .003), BPT (F(2, 85.59) = 4.56, P = .013), and DLD (F(2, 103.56) = 4.48, P = .014). SIB progression (PR) had a faster decline in performance versus no‐dementia (ND) (t(159) = −2.87; P = .013). Dementia had a faster decline in BPT performance versus ND (t(112) = −2.46; P = .041). PR showed quickly progressing scores compared to ND (t(128) = −2.86; P = .014). Discussion Current measures demonstrated moderate to good reliability. Longitudinal analysis revealed that SIB, BPT, and DLD changed with age depending on diagnostic progression; no change rates were dependent on baseline cognition, indicating usefulness across a variety of severity levels in DS.

Cognitive Function during the Prodromal Stage of Alzheimer’s Disease in Down Syndrome: Comparing Models

“…Early detection of Alzheimer’s disease (AD) is of paramount importance to enhance efficacy of clinical intervention and to improve understanding of AD progression in people with Down syndrome (DS). Due to the triplication of the amyloid precursor protein gene on chromosome 21, people with DS have life-long overproduction of amyloid-β, and the earlier production of amyloid- β in this population, detectable in imaging studies as early as 14 years of age, contributes to increased AD risk [ 1 , 2 ]. That is, adults with DS are likely to experience earlier AD-related cognitive declines than their counterparts in the neurotypical population [ 3 ].…”

“…Complicating early detection of AD progression and diagnostic accuracy is the large variability in baseline cognitive ability among people with DS, ranging from borderline intellectual functioning to profound impairment [ 2 , 4 , 5 ]. Diagnosis of any form of intellectual disability (ID) requires an intelligence quotient (IQ) that is two or more standard deviations (SD) below the population mean, and the range in IQ within the population with DS can be more than 50 points [ 6 ], equivalent to over 3 SDs.…”

“…In the neurotypical population, the prodromal stage of dementia (i.e., mild cognitive impairment; MCI) is typically diagnosed based upon decline, together with performance that is 1.5 SDs or more below the population mean on cognitive tests [ 7 , 8 ]). However, this criterion cannot be applied to the population with DS since the vast majority of affected individuals have functioned more than 1.5 SDs below the mean since childhood [ 2 , 3 ]. The lack of data on normative age-related declines in cognition among healthy adults with DS also makes it difficult to differentiate between expected age-related declines and MCI [ 9 ].…”

Executive Functioning in Adults with Down Syndrome: Machine-Learning-Based Prediction of Inhibitory Capacity

“…Along with perceptual-motor functioning, performance in constructional praxis tests requires the ability to plan and organize actions, which draws upon processes of executive function. Indeed, recent studies showed that both praxis and inhibitory capacity decline in aging [51,71]. Second, verbal short-term memory predicted inhibitory function.…”

Cognitive and Behavioral Domains That Reliably Differentiate Normal Aging and Dementia in Down Syndrome

“…In recent studies, our group has sought to establish an evidence base for abbreviated neurobehavioral examination procedures appropriate for in-office dementia monitoring by community practitioners caring for patients with DS [21]. Performance measures in our long-term cohort studies include the Brief Praxis Test (BPT) [22] and the Severe Impairment Battery (SIB) [23].…”