[Late-onset schizophrenia: is it a dementia nonpraecox? Review article with advice on differential diagnosis]

For many years now researchers have been discussing whether late-onset schizophrenia (LOS) is in fact a separate subgroup of schizophrenia. They also want to find out whether LOS has a neurodegenerative aetiology and is a progressive illness.

To obtain insight into the clinical aspects, aetiological factors and the course of late-onset schizophrenia. In addition, advice is given about better ways of diagnosing LOS in clinical practice and about differentiating LOS from dementia.

The literature was searched via Medline and the Cochrane Library on the basis of the key words '(very) late-onset schizophrenia' and 'paraphrenia' combined with 'course', 'outcome', 'cognition', 'decline', 'white matter hyperintensities', 'MRI', and 'neuropsychological', 'postmortem' and cerebrospinal fluid'. The period studied was from 1960 to November 2004.

Clinical parameters andfunctional and structural brain research point to differences from and similarities to the early form of schizophrenia (EOS). In cases of 'very-late-onset schizophrenia-like psychosis' (VLOS) the clinical differences vis-à-vis EOS are even more marked. It is not known to what extent neurodegenerative factors play a role. There is no clear consensus about the course of (V)LOS either.

In view of the aetiologial and physiopathological factors it is still not clear whether (V)LOS can be differentiated from EOS on a neurobiological basis. There is insufficient proof about the extent to which (V)LOS is a dementia nonpraecox with neurodegenerative aetiology. To achieve clear differentiation between the various forms of dementia it is essential that the clinical diagnosis of LOS is supported as strongly as possible and is evaluated continually.