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As
noted earlier in this chapter, most complaints of dry mouth are
a result of altered salivary gland function. There are other causes,
however, including sensory changes in the mouth, often following
a CVA or surgical procedure, dehydration, and cognitive alterations.
Dry mouth may be a manifestation of anxiety or depression, even
without obvious changes in salivary output (Fox
et al., 1985).
Drug use
The most common cause of dry mouth complaints is drug use (Sreebny
and Schwartz, 1997). Interestingly, xerostomia is a frequent
side effect of many pharmaceuticals, in spite of a lack of change
in salivary performance. There are examples of drugs which have
prominent dry mouth complaints associated with their use which
have been found in clinical trials to have no affect on salivary
performance (Atkinson
et al., 1989; Scully,
2003). Whether this is a result of alterations in some unrecognized
salivary component(s) is not known. It is also possible that such
drugs may cause other, central alterations that result in the
dry mouth symptoms.
However, there
are many drugs that do cause reductions in salivary function.
Prominent among these are:
- Antidepressants
- Antihistaminics
- Narcotics,
and
- Certain
antihypertensives.
Studies have
shown that with increasing numbers of drugs used, the incidence
and severity of xerostomia increases, as well (Pajukoski
et al., 2001; Wu
and Ship, 1993). This has a great impact in older populations
where prescription drug use is high.
Radiotherapy
Xerostomia is a prominent problem following radiotherapy that
includes the salivary glands in the treatment fields. At total
delivered doses above 50 Gy, the resultant salivary dysfunction
is severe and persistent (Vissink
et al., 2003)
Other cancer
therapies induce dry mouth complaints (Jensen
et al., 2003). During bone marrow or peripheral stem cell
transplantation, xerostomia is frequent and may become chronic
if GVD develops. Xerostomia is also common with several chemotherapeutic
regimens and may persist throughout treatment.
Systemic
disease
Systemic disease is another major cause of xerostomia (Wotman
and Mandel, 1973). Prominent among conditions with dry mouth
symptoms is Sjögren's syndrome, an autoimmune exocrinopathy.
Other systemic conditions where dry mouth is a frequent complaint
include diabetes, thyroid disorders, connective tissue diseases
and cystic fibrosis.
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