Our research shows that loss of insight is often a very distressing part of Alzheimer's disease for families, whereas, of course, it is less distressing to the patients themselves. Indeed, an early worry about drug treatment of Alzheimer's disease was that it might restore insight but not function - in other words, patients might again go through the agony of being aware of their loss. While this does happen, in our experience it is very uncommon, and can sometimes be treated by adding an anti-depressant medication . One of the most intriguing experiences that, as physicians, we are privileged to see in people with Alzheimer's disease is the way that they rebuild their sense of self with successful treatment. This is discussed in more detail in Rockwood K, et al., The treatment of Alzheimer's disease: success short of cure. Lancet Neurol. 2003;2:630-3.
The idea of self is a complicated one. It is frightening to think that a person can lose their sense of self. On the other hand, one of the most rewarding signs that treatment for Alzheimer disease is working, is when a person is described (or describes on their own) as being more like their old self.
Some recent work has begun to formally explore how people with dementia perceive themselves - in particular their capabilities (e.g. Graham DP et al., Self-reported awareness of performance in dementia. Brain Res Cogn Brain Res. 2005 May 23 and Rankin KP et al., Self awareness and personality change in dementia. J Neurol Neurosurg Psychiatry. 2005 May;76(5):632-9.)