Alzheimer's Disease in People with Down Syndrome - Diagnosis

Recognizing the early stages of Alzheimer's disease is difficult in people with Down syndrome. People with Down syndrome have a wide range of health problems as they age, and some of these may mimic or hide the presence of Alzheimer's disease. Also, the usual diagnostic tests used for diagnosis of Alzheimer's disease in people without Down syndrome do not take into account the existing disabilities of the person with Down syndrome. Many people with Down syndrome cannot be evaluated by standard psychological tests. Finally, some people with Down syndrome have limited verbal and other communication skills that may make assessment difficult. For these reasons, the methods used for testing for Alzheimer's disease in people without Down syndrome (for example, Mini Mental Status Examination) are unreliable in people with Down syndrome.

Tests for Alzheimer's disease in people with Down syndrome

Several clinical tools have been designed that are more appropriate for diagnostic use in people with Down syndrome. Many of these tests focus on changes related to a decline in activities of daily living (ADL) such as eating, dressing, and bathing. Most of this information can be obtained by interviewing relatives or caregivers. The following are some tests appropriate for people with Down syndrome:

• Alzheimer's Functional Assessment Tool - Useful for follow-up
  
  
• Dementia Scale for Down Syndrome (DSDS) - Useful for screening, especially in the middle or late stage of Alzheimer's disease
  
  
• The Dementia Questionnaire for Mentally Retarded Persons - Useful for screening for Alzheimer's disease

The medical work-up for the diagnosis of Alzheimer's disease, that is, blood tests and neuroimaging studies (CT scan, MRI), is the same as for individuals without Down syndrome. The three tests mentioned above are questionnaires or scales to assess or document the evolution of dementia. Blood tests may be obtained to rule out certain other causes of dementia, such as infection, metabolic disorders (like thyroid imbalance), or medication effects.