Misdiagnoses in the elderly: pseudodementia due to depression or pseudodepression due to dementia?


Distinguishing between dementia and depression in the elderly may sometimes be tricky. When memory lapses or word finding difficulties become conspicuous in an elderly individual, there is usually little doubt that an early stage of a dementing process, or at least “mild cognitive impairment” is present. But what if the symptomatology is dominated by apathy, hesitations, inability to initiate behaviors, and affective flatness? The the diagnosis of “pseudodementia due to depression” is likely to be made. What not every clinician realizes, however, is that these symptoms may be due to a dementing process with a frontal-lobe onset. It is not by chance that in the old European neurological literature the syndrome associated with the dorsolateral prefrontal damage was known as “psudodepressed.” So whenever such changes are encountered in an elderly individual the possibility of a dementing process with frontal-lobe onset must be considered.Ironically, DSM-IV contributes to the potential for misdiagnosis by making memory impairment an obligatory component of dementia. In reality, while memory impairment may be the most common early manifestation of dementia, it is not the only one. Subtle executive deficit signaling early frontal-lobe involvement in the disease process is not infrequently the first manifestation of disease and it is important not to misdiagnose it as depression.

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