A comprehensive dementia evaluation includes a full physical examination by a trained specialist who understands assessment procedures for persons with IDD (McCarron et al., 2014). The National Task Group Recommendations for the Evaluation and Management of Dementia (Moran et al., 2013) describe the steps of an evaluation to include gathering medical and psychiatric history, obtaining a description of the person's current functioning and comparing it to his or her baseline, a thorough physical examination including a review of systems and the medication list, obtaining pertinent family history, and assessing for psychosocial issues.
Significant psychosocial issues may include leaving the family home, frequent turnover/departure of paid caregivers, witnessing the declining health or death of someone close to the individual, and experiencing decline in one's own health, functional ability, or employment status. Assessment of these issues could identify triggering events or coexisting disorders that can influence an individual's cognitive and functional performance (Moran et al., 2013).
Magnetic resonance imaging (MRI) plays a limited role in the diagnosis of AD in individuals with Down syndrome. MRI can detect changes in the brain associated with AD but currently has limited validity and reliability. MRI findings are to be considered in combination with clinical assessment (Prasher, 2003).
Often a person with IDD, including Down syndrome, may demonstrate dementia symptoms but may not be evaluated until his or her care providers are troubled by the behavior (Strydom et al, 2010). One study presented case examples of "diagnostic overshadowing," where service providers or family members attribute the onset of new symptoms to a person's Down syndrome rather than considering the potential for dementia. Families in this study were not aware of the potential for early-onset AD in their relative and, once they noticed behavioral changes, sought psychiatric assessment rather than evaluation for dementia. The potential for overshadowing is heightened when care providers lack knowledge or understanding of intellectual disability and the potential for AD or another dementia. Overshadowing can lead to provision of poor or inappropriate supports and inadequate care management (Carling-Jenkins et al., 2012).