[The elderly and dementia: clinical approach].

When you take care of elderly, you need to evaluate cognitive functions due to the frequency of dementia. However, before this evaluation, you must be aware of difficulties that you will encounter. You have to determine general characteristics of elderly patients and use geriatric reasoning in order to list pathologies that can interfere with cognitive functions. Thereafter, you need to precise frontiers between normal cognitive functions and dementia. When dementia is confirmed, CT scan or MRI appears very useful to exclude a cause of reversible dementia or to precise the nature of dementia. CT scan or MRI are useful during dementia to define the etiology of dementia or acute deterioration during evolution. A close collaboration between radiologist and clinician is mandatory to avoid diagnostic errors.