While it is relatively easy to distinguish between functional and non-functional psychoses in adults, we find that matters become rather complex in old age, beginning let us say at the age of 65. There is almost always an overlapping of different factors, some of them specific to old age and others to the lifetime's experience of the individual. If we undertake to draw up a list of these factors, they would include the following.

The immediate environment

It is important in our pathogenetic hypotheses to note whether an aged person lives alone, in a family or in an institution. Social and affective isolation has been identified as one of the major factors in explaining psychic decompensation in the period of senescence.

The socioeconomic factor

It is a commonplace to assert that a person who has prepared for his retirement, who can carry out activities which interest him beyond the arbitrary limits of age, has a protective space around him against intolerable frustrations and against what Balier, has described in his theory of aging as ‘the emptying of the positive content of narcissism, that is self esteem’.

Cerebral functioning

Physiological involution of the central nervous system appears, sooner or later, in old age. The variations are very great. We know centenarians with virtually intact intellectual capacities whereas, in other persons, reduction in the ability to adapt and learn, an impoverishment of imagination, and also a reduced capacity for storing engrams, are perceptible very early. Much has been said and written about the so-called involutive or psycho-organic element, in various functional psychoses of advanced years. While some authors attribute to this only a very secondary role and dispute the dogma of a ‘defectology’, others (on the basis of systematic investigations) demonstrate that a psycho-organic component may play a considerable role in triggering and maintaining functional psychoses in aged people.

Predispositions/ personality traits

In our own studies, we have found that, despite certain accentuations, the character remains the same up to an advanced age and that even in the deepest demential states we can still recognize typical personality traits that have persisted throughout the life of the individual. These predispositions may therefore influence, if not the origin, at least the form and content of a functional psychosis.