Treponema denticola Has the Potential to Cause Neurodegeneration in the Midbrain via the Periodontal Route of Infection-Narrative Review.

Alzheimer's disease (AD) is a neurodegenerative disease and the most common example of dementia. The neuropathological features of AD are the abnormal deposition of extracellular amyloid-ß (Aß) and intraneuronal neurofibrillary tangles with hyperphosphorylated tau protein. It is recognized that AD starts in the frontal cerebral cortex, and then it progresses to the entorhinal cortex, the hippocampus, and the rest of the brain. However, some studies on animals suggest that AD could also progress in the reverse order starting from the midbrain and then spreading to the frontal cortex. Spirochetes are neurotrophic: From a peripheral route of infection, they can reach the brain via the midbrain. Their direct and indirect effect via the interaction of their virulence factors and the microglia potentially leads to the host peripheral nerve, the midbrain (especially the locus coeruleus), and cortical damage. On this basis, this review aims to discuss the hypothesis of the ability of Treponema denticola to damage the peripheral axons in the periodontal ligament, to evade the complemental pathway and microglial immune response, to determine the cytoskeletal impairment and therefore causing the axonal transport disruption, an altered mitochondrial migration and the consequent neuronal apoptosis. Further insights about the central neurodegeneration mechanism and Treponema denticola's resistance to the immune response when aggregated in biofilm and its quorum sensing are suggested as a pathogenetic model for the advanced stages of AD.

Locus Coeruleus Dysfunction and Trigeminal Mesencephalic Nucleus Degeneration: A Cue for Periodontal Infection Mediated Damage in Alzheimer's Disease?

Alzheimer's disease (AD) is a leading neurodegenerative disease with deteriorating cognition as its main clinical sign. In addition to the clinical history, it is characterized by the presence of two neuropathological hallmark lesions; amyloid-beta (Aß) and neurofibrillary tangles (NFTs), identified in the brain at post-mortem in specific anatomical areas. Recently, it was discovered that NFTs occur initially in the subcortical nuclei, such as the locus coeruleus in the pons, and are said to spread from there to the cerebral cortices and the hippocampus. This contrasts with the prior acceptance of their neuropathology in the enthorinal cortex and the hippocampus. The Braak staging system places the accumulation of phosphorylated tau (p-tau) binding to NFTs in the locus coeruleus and other subcortical nuclei to precede stages I-IV. The locus coeruleus plays diverse psychological and physiological roles within the human body including rapid eye movement sleep disorder, schizophrenia, anxiety, and depression, regulation of sleep-wake cycles, attention, memory, mood, and behavior, which correlates with AD clinical behavior. In addition, the locus coeruleus regulates cardiovascular, respiratory, and gastrointestinal activities, which have only recently been associated with AD by modern day research enabling the wider understanding of AD development via comorbidities and microbial dysbiosis. The focus of this narrative review is to explore the modes of neurodegeneration taking place in the locus coeruleus during the natural aging process of the trigeminal nerve connections from the teeth and microbial dysbiosis, and to postulate a pathogenetic mechanism due to periodontal damage and/or infection focused on Treponema denticola.

The Mechanistic Pathways of Periodontal Pathogens Entering the Brain: The Potential Role of Treponema denticola in Tracing Alzheimer's Disease Pathology.

Alzheimer's Disease (AD) is a complex neurodegenerative disease and remains the most common form of dementia. The pathological features include amyloid (Aß) accumulation, neurofibrillary tangles (NFTs), neural and synaptic loss, microglial cell activation, and an increased blood-brain barrier permeability. One longstanding hypothesis suggests that a microbial etiology is key to AD initiation. Among the various periodontal microorganisms, Porphyromonas gingivalis has been considered the keystone agent to potentially correlate with AD, due to its influence on systemic inflammation. P. gingivalis together with Treponema denticola and Tannerella forsythia belong to the red complex consortium of bacteria advocated to sustain periodontitis within a local dysbiosis and a host response alteration. Since the implication of P. gingivalis in the pathogenesis of AD, evidence has emerged of T. denticola clusters in some AD brain tissue sections. This narrative review explored the potential mode of spirochetes entry into the AD brain for tracing pathology. Spirochetes are slow-growing bacteria, which can hide within ganglia for many years. It is this feature in combination with the ability of these bacteria to evade the hosts' immune responses that may account for a long lag phase between infection and plausible AD disease symptoms. As the locus coeruleus has direct connection between the trigeminal nuclei to periodontal free nerve endings and proprioceptors with the central nervous system, it is plausible that they could initiate AD pathology from this anatomical region.

Comorbidity of obsessive-compulsive disorder and attention-deficit/hyperactivity disorder in referred children and adolescents.

OBJECTIVE: The aim of this study was to explore whether comorbid attention-deficit/hyperactivity disorder (ADHD) affects the clinical expression and outcome of obsessive-compulsive disorder (OCD) in a clinical sample. METHOD: A consecutive series of 94 children and adolescents (mean age, 13.6 +/- 2.8 years) with current diagnosis of OCD were included in the study. Twenty-four (25.5%) patients were diagnosed as having a comorbid ADHD. Subjects with OCD plus ADHD were compared with subjects with OCD but without ADHD. RESULTS: Comorbid ADHD with OCD was significantly associated with a higher rate of males, an earlier onset of OCD, a greater psychosocial impairment, and a heavier comorbidity, namely, with bipolar disorder, tic disorder, and oppositional defiant disorder/conduct disorder. Phenomenology of obsessions and compulsions and outcome were not affected by ADHD comorbidity. CONCLUSIONS: A screening for ADHD should be performed in patients with OCD, as these patients and their parents are frequently not aware that the impairment may be partly due to a comorbid ADHD.

A naturalistic study of referred children and adolescents with obsessive-compulsive disorder.

OBJECTIVE: To report on clinical features, comorbidity, and response to pharmacotherapy in children and adolescents with obsessive-compulsive disorder (OCD) naturalistically followed and treated with serotonin reuptake inhibitors (SRIs). METHOD: A consecutive series of 94 patients (65 males, 29 females, age 13.6 +/- 2.8 years), referred in the period January 2001-April 2004, diagnosed with a clinical interview (Diagnostic Interview for Children and Adolescents-Revised), and followed for 10 +/- 6 months, were included in the study. RESULTS: Contamination obsessions and washing rituals were associated with less impairment than other subtypes of OCD. Aggressive sexual obsessions and checking rituals as well as symmetry obsessions and ordering-repeating rituals were more frequently comorbid with tic disorders. According to the Clinical Global Impressions-Improvement scale (score 1 or 2), 63 subjects (67%) were responders to treatment. Nonresponders were more severely impaired and had a higher number of comorbid disorders, namely, bipolar disorder and conduct disorder (p < .05). Forty-seven patients (50%) received an SRI monotherapy, whereas the other 47 (50%) needed other medications. Patients receiving SRI monotherapy were less severely impaired; had a later onset of OCD; were at a younger age at the visit, had higher rates of depression and anxiety and lower rates of bipolar disorder, attention-deficit/hyperactivity disorder, and conduct disorder (p < .05). CONCLUSIONS: Long-term naturalistic prospective studies in pediatric patients with OCD might represent an important source of information for everyday care regarding the effectiveness of a treatment over extended periods of time under routine clinical conditions.