The Possible Causal Link of Periodontitis to Neuropsychiatric Disorders: More Than Psychosocial Mechanisms.

Increasing evidence implies a possible causal link between periodontitis and neuropsychiatric disorders, such as Alzheimer's disease (AD) and major depression (MD). A possible mechanism underlying such a link can be explained by neuroinflammation induced by chronic systemic inflammation. This review article focuses on an overview of the biological and epidemiological evidence for a feasible causal link of periodontitis to neuropsychiatric disorders, including AD, MD, Parkinson's disease, and schizophrenia, as well as the neurological event, ischemic stroke. If there is such a link, a broad spectrum of neuropsychiatric disorders associated with neuroinflammation could be preventable and modifiable by simple daily dealings for oral hygiene. However, the notion that periodontitis is a risk factor for neuropsychiatric disorders remains to be effectively substantiated.

High salivary alpha-amylase levels in patients with schizophrenia: A pilot study.

Previous studies have demonstrated the autonomic dysregulation in patients with schizophrenia using electrophysiological methods, such as electrodermal measures and heart rate analysis. Several theories have been proposed to explain the underlying mechanisms of schizophrenia and its autonomic function. Recently, the measurement of salivary alpha-amylase has been considered to be a useful tool for evaluating the sympathetic-adrenal-medullary (SAM) system. Psychosocial stress increases the release of salivary alpha-amylase. Although some studies have evaluated salivary alpha-amylase under psychosocial stress, no studies have demonstrated the change in the salivary alpha-amylase (sAA) activity level in schizophrenic patients. We examined the relationship between sAA level and psychiatric state in patients with schizophrenia (n=54) using a portable and rapid hand-held monitor to investigate sAA. The sAA activity in the patients was significantly higher than that in the control subjects (n=55) (p<0.01). The correlation between amylase level and psychiatric symptoms was highly significant (r=0.37, p<0.01). These findings indicate that higher increases in sAA may indicate severe psychiatric symptoms. These results indicate a predominant role of the sympathetic nervous system in the secretion of sAA, together with parasympathetic withdrawal, under psychosocial stress.