False teeth and Alzheimer's disease

As part of a serious study on the natural history of AD, it was noted during physical examination whether the patient had false teeth or not. The oral cavity was visually examined by asking the patient to open the mouth and the examiner peered in. The presence of false teeth was operationally defined as "the absence of natural teeth and their replacement, however episodic, with false ones". This overcame the problem of patients who kept their false teeth in a pocket or handbag. At least 50% of the teeth needed to be false to fulfil the definition. If the patient was uncooperative, information was sought from relatives and care staff. Inter-rater reliability as to presence or absence of false teeth was excellent (100%), i.e. no raters disagreed as to presence or absence of false teeth. The diagnosis of AD was made on clinical grounds using strict standardised criteria (McKhann et al. 1984), each patient undergoing a physical and mental state examination (Folstein et al, 1975) and computed tomography (CT) scan. As per the authors' usual practice, expert statistical advice was sought and then completely ignored. A 'statisti cal screen' (or 'data trawl') was performed using

dementia and affects about 6% of people over the age of 65. The aetiology is unknown and putative causes range from environmental toxins (Martyn et al, 1989) to chromosome abnormalities (St George Hyslop et al, 1987). Despite the extensive resources being channelled into AD research, it is surprising that no study has yet discussed the role of false teeth.

Subjects and methods
As part of a serious study on the natural history of AD, it was noted during physical examination whether the patient had false teeth or not. The oral cavity was visually examined by asking the patient to open the mouth and the examiner peered in. The presence of false teeth was operationally defined as "the absence of natural teeth and their replacement, however episodic, with false ones". This overcame the problem of patients who kept their false teeth in a pocket or handbag. At least 50% of the teeth needed to be false to fulfil the definition. If the patient was uncooperative, information was sought from relatives and care staff. Inter-rater reliability as to presence or absence of false teeth was excellent (100%), i.e. no raters disagreed as to presence or absence of false teeth. The diagnosis of AD was made on clinical grounds using strict standardised criteria (McKhann et al. 1984), each patient undergoing a physical and mental state examination (Folstein et al, 1975) and computed tomography (CT) scan. As per the authors' usual practice, expert statistical advice was sought and then completely ignored. A 'statisti cal screen' (or 'data trawl') was performed using every available statistical procedure known and only the significant results were recorded. In the spirit of Smeeton (1991) and in an attempt to impress referees, confidence intervals for diffÃ©rences between groups were also calculated, (see Table).

Findings
The presence or absence of false teeth was assessed in 159 patients. Over half of the patients had false teeth and their presence was associated with an increased age and later age of onset of the dementia. Patients with false teeth were less cognitively impaired, had more temporal lobe atrophy on CT scan and there was a trend for them to more often have a family history of dementia. The examination for false teeth was found acceptable to patients and no ethical problems were encountered. Several patients had two sets of false teeth, but these were only counted once.

Discussion
To our knowledge, this is the first study to investigate the presence or absence of false teeth in a neuro psychiatrie disorder. The older age of the patients with dentures and their lesser degree of cognitive impairment may suggest a subtype of AD based on the presence or absence of false teeth. The trend towards an increased family history of dementia in patients with false teeth suggests a genetic pre disposition to both, although this finding did not quite reach statistical significance despite great Burns el al efforts by the authors. The association between the presence of false teeth and temporal lobe atrophy on CT scan may be as a result of reduced mastication leading to disuse atrophy of the limbic system. Further studies (including case control studies) are essential, particularly on the effects of fluoridation of the local water supply and whether the acquisition of false teeth is before or after the onset of dementia. It may be that future research into AD should be directed more towards the mouth than the brain.  Research, 12, 189-198. MARTYN, C, BARKER, D., OSMOND, C. et al (1989) Geographical relation between Alzheimer's disease and aluminium in drinking water. Lancet, \. 59-62. MC-K.HANN,G., DRACHMAS. D., FOLSTEIN,M. et al (1984) Clinical The social model of health has particular relevance given that deaf people are often frustrated in their dealings with the hearing world. Specialist social workers with deaf people, with knowledge, aware ness and communication skills are thin on the ground; trained, deaf social workers rarer still. They end up giving psychiatric opinions to generic health workers, because, for example, general practitioners have few of the appropriate skills and knowledge to make a proper assessment: the deaf person is often marginalised by this process.
The question 'Communication: disorder, depri vation or discrimination' was raised by Ms Alice Thacker, a Mental Health Foundation research fellow. Many deaf people with mental health