Which clinical history findings are characteristic of early stage Alzheimer disease (AD) in Down syndrome (DS)?

Updated: Nov 13, 2019
  • Author: Norberto Alvarez, MD; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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Answer

Answer

In the author's research, typically the first symptoms, most often identified retrospectively, are observed when the patient is aged 50 years (range, 36-62.5 y) and the diagnosis is confirmed at age 52.6 years (range, 37-62 y). Others have reported early signs of intellectual deterioration occurring in patients in their 40s. [68] Death occurs at a mean age of 60.11 years (range, 46.7-69.8 y). The author's research has also shown that the duration of the disorder from first symptoms to death is 9.10 years (range, 6.9-11.10 y), and the duration from diagnosis to death is 8.2 years (range, 5-12.4 y).

The main symptoms are confusion, disorientation, and wandering. In most instances, these early signs are not recognized and commonly are misdiagnosed.

Longitudinal studies showed progressive cognitive decline and subtle memory loss as early symptoms, which are associated with deficits in visuospatial organization. [66, 67] . For example, a modified version of the Cued Recall Test [66] showed a high degree of sensitivity (94.7%)  and  specificity (93.9%) and a high positive predictive value for AD in DS (81.9%). 

Behavioral changes include the following:

  • Deficits and variability in tests of selective attention (ie, the ability to stay focused on a particular stimulus, disregarding other stimuli) might be a subtle early sign of AD that can be documented by a relatively easy test. [69]

  • In the early stage of the disease, behavioral changes are the most common sign; these changes are usually considered an exaggeration of long-standing behavioral traits (eg, refusal to follow certain orders or to do chores at home may be perceived as stubbornness)

  • Because the early changes are subtle, only those familiar with the individual would be able to recognize them (such changes include change in daily routine, change in sleeping or eating habits, inability to make clothing decisions, getting lost in familiar environments, and inability to remember the names of familiar people); one of the potential early signs of AD in highly functional DS individuals is the inability to perform job duties

  • As the disease progresses, there is an increase in maladaptive behaviors such as aggression, unjustified fears, sleep problems, and social inadequate behaviors [70]

Visual deficiencies include the following:

  • Impairment in visual perception as a consequence of central processing dysfunction has been described in the early stage of AD in individuals with DS who have a relatively high level of intelligence

  • Central processing dysfunction is more difficult to delineate in patients with DS who have severe mental retardation

  • These central changes are magnified by peripheral visual disorders (eg, cataracts, myopia, astigmatism), which are frequently present in people with DS

  • The visual deficiencies may be responsible for individuals getting lost in familiar environments, not being able to perform activities that require visuo motor coordination, increased frequency of accidents and falls, and difficulty in learning new tasks

Impaired learning ability is usually present in the early stages of the disease but is difficult to demonstrate in people with a moderate or more severe degree of mental retardation.

Other indications of early deterioration include loss of language and other communication skills, impairment of social and adaptive skills, and progressive loss of activities of daily living (ADLs) (eg, personal hygiene, dining skills, and bathroom skills).


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