Alzheimer’s Disease and Oral Health: The Plausible Links

Alzheimer’s Disease (AD) is the leading cause of dementia in the U.S. elderly population. It is a progressive dementia characterized by early short-term memory impairment. Sadly, the annual cost in the U.S. for care, lost productivity, and resource loss involving individuals with AD is approximately $100 billion. That’s a TON of money!

Technically, AD is characterized pathologically by the presence of pathological structures in the brain, such as neurofibrillary tangles, neuropil threads, and beta-amyloid plaques; however, the presence or  absence of these structures doesn’t mean the person has AD, but the final diagnosis must include some of these.

Sadly enough, there are no effective therapies as of yet, and most efforts have been at prevention. Worse, the etiologies (causes) of the disease are unknown. Those people who are at greatest risk are the aging (all of us) and family history of AD. There is increasing evidence that supports the involvement of oxidative stress in the body. Most importantly, there is increasing evidence between the association of gum disease and AD, which I want to talk about here.

Spread of bacteria to distant sites

It is well-documented that oral bacteria will travel to other sites in the body through the bloodstream or nerve pathways. The first study that determined this was in 1891! Could this spread also infect the brain? Very possibly. One study showed positive cultures if oral bacteria in arterial blood in 55% of patients with severe gum disease – not good AT ALL.

Injury to brain from systemic inflammatory mediators

It is also possible that oral bacteria do not “infect” the brain but rather  induce a systemic inflammatory response leading to injury of the brain tissue. Several studies implicate the role of inflammation in the  pathophysiology of several psychiatric disorders, including AD.

Gum disease increases risk of cerebrovascular injury to brain

There are two types of stroke: one where a blood vessel in the brain ruptures, and one where blood is blocked by a clot OR an aggregation of bacteria and fibrin from a distant source. Unfortunately, the risk of dementia increases 9X  for those experiencing the second type of stroke.

Even worse, gum disease affects platelet and blood coagulation and influences clot formation!

Genetics and inflammatory responses

Some genetic types predispose one to high risk favoring chronic inflammation. These individuals with particular variation in a certain gene cluster are at increased risk of developing AD.

Surprisingly, these genetic variations are common themes between gum disease and AD.

Weight loss and wasting

Gum disease contributes by causing tooth loss, causing problems with chewing, swallowing, and food selection. This results in poor food absorption, and thus nutritional deficiencies follow. It may shock you, but tooth loss before the age of 35 was shown to be strongly associated with AD! Weight loss is also associated with the effects of bacterial products and inflammation.


There is much research going on, and there will undoubtedly continue to be as AD becomes nearly epidemic in our aging population.
It’s important to know that AD contributes to decline in oral health, and it’s very plausible that a decline in oral health contributes to AD!

It’s also important to remember that several biologically plausible mechanisms are presented; it has not been “proven” that AD is directly linked to gum disease. In fact, because, AD appears to be multi-factorial, one mechanism is unlikely, and one mechanism may “tip the scale” in favor of AD!

Many factors are uncontrollable in AD, but gum disease and oral infection CAN BE PREVENTED. In reality, time may tell that gum disease may be one of those factors that tip the scale, because it is implicated in many systemic diseases.