Dementia is the term applied to illnesses where memory and other higher mental functions are affected and includes illnesses such as Alzheimer's disease.

In pseudo-dementia, patients' memory appears to be affected, but closer examination will reveal that they are inattentive to their surroundings and hence unable to retain new information in the form of new memories. Also they are able precisely to date the onset of this impairment and are acutely aware that memory is insufficient. Their slowness and apathy is, of course, similar to the effects of dementia. However, other signs and symptoms of depression are usually present. The significance is that depression in this age group, unlike dementia, can generally be successfully treated if recognized.