I believe, psychologically speaking, he has a condition known as Anosognosia, and have believed this for a while. It may be helpful to someone else in his or her understanding of this condition in relation to an individual other than Joe. You never know. An explanation of Anosognosia is copied and pasted below:

The denial of mental illness that goes beyond mere psychological denial is called anosognosia and it is the clinical term for the lack of insight required to understand you have a mental illness. Anosognosia is a neurological disorder thought to be caused by abnormalities in the frontal lobes. Put another way, anosognosia is the lack of awareness of the deficits, signs and symptoms of an illness. It is not merely a denial; it is an actual neurological deficit.

Impaired awareness of illness is a strange thing. To others, psychiatric symptoms seem so obvious it’s hard to believe the person experiencing them is not aware he/she is ill. Oliver Sacks, in his book The Man Who Mistook His Wife for a Hat, noted this problem: "It is not only difficult, it is impossible for patients with certain right-hemisphere syndromes to know their own problems.... And it is singularly difficult, for even the most sensitive observer, to picture the inner state, the 'situation' of such patients, for this is almost unimaginably remote from anything he himself has ever known."