New research increasingly shows that not only are many cognitive disorders such as Alzheimer's and other forms of dementia related to inflammation in brain tissues, but even so-called ‘classic’ mental diseases such as schizophrenia and depression may be connected to brain inflammation. Further, recent research from Japan's Kyushu University Medical School and Saga University have shown that many mental disorders are the direct result of inflammation involving microglial cells of the brain.

Microglia are the resident macrophages of the brain and spinal cord, and thus act as the first and main form of active immune defense in the central nervous system (CNS). Microglia constantly scavenge the CNS for plaques, damaged neurons and infectious agents. The brain and spinal cord are separated from the rest f the body by a series of cells known as the blood-brain barrier, which prevents most infections from reaching vulnerable nervous tissue. In the case where infectious agents and toxins are directly introduced to the brain or cross the blood-brain barrier, microglial cells react quickly to decrease inflammation and destroy the infectious agents before any damage occurs. Because antibodies from the rest of the body cannot penetrate the blood-brain barrier, microglia must be able to recognize foreign bodies, swallow them and act as antigen-presenting cells activating T-cells. This process must be done quickly to prevent potentially fatal damage; hence, the microglia are extremely sensitive to even small pathological changes in the CNS.

Buildup of amyloid plaque is seen in certain brain cells in Alzheimer's disease and other forms of dementia, and is believed to be a result of damage from oxidative stress. Microglia prevent this buildup and clean up amyloid plaque. No wonder that when microglia are damaged, the brain and nervous system become increasingly susceptible to mental disorders such as dementia, schizophrenia and depression.

Neuro-inflammation is the result of damage to the brain and nervous system. Healthy microglia work to block neuronal inflammation and prevent damage to brain cells. When brain cells do get damaged, microglia work to repair the damage by producing a variety of inflammatory factors. Like other macrophages, microglia are formed within the bone marrow. Once they migrate to the brain, they differentiate into particular responsibilities and different regions. Some microglia deal with infections, others are focused upon toxins or damaged cells. Still others stimulate the repair of brain tissues.

Research has connected mental disorders such as schizophrenia, depressive states and other cognitive health issues to increases in microglia-related inflammatory factors, such as nitric oxide and cytokines. Microglia produce these inflammatory factors in response to damage to brain cells. The brains of schizophrenia, depression and dementia patients have increased levels of microglia-related inflammatory factors. Furthermore, research shows that one of the central mechanisms of psychiatric drugs is that they reduce levels of these inflammatory factors—but only temporarily. This temporary reduction of inflammatory factors does little to prevent or address the original cause of the inflammation. By blocking inflammatory factors, these drugs interfere with microglia-driven damage repair that is taking place; as is often the case when drugs act on symptoms, rather than causes of a disease condition.

The cause of neuro-inflammation, as shown in numerous dementia studies, appears to be oxidative damage. Oxidation is caused by an imbalance between toxins that form harmful oxidative radicals and a range of antioxidants that neutralize those radicals. When there are not enough antioxidants in a given system, oxidation takes place; for example, in the cells of the cardiovascular system as well as in brain cells. This is why recent research has linked cognitive decline to increased obesity, diabetes and heart disease.

A new French and Finnish INSERM study, with support from the U.S. National Institutes of Medicine, examined 6,401 adults between 39 and 63 years old. People who were obese and suffered from metabolic disorders, including cardiovascular disease and/or diabetes, were seen to exhibit more than a 22% greater cognitive decline than those of normal weight with no metabolic disorders. The results of this study are supported by other studies that have related cognitive decline to cardiovascular disease, sedentary lifestyles, obesity and increased levels of toxins, all of which are associated with higher levels of inflammation.

Numerous studies have shown that antioxidants neutralize oxidative radicals that produce inflammation. The very term ‘antioxidant’ is founded upon research showing that particular naturally produced phytochemicals directly neutralize the oxidative effects of radicals formed by toxins. For example, in another large French study, researchers found that a healthy diet with greater antioxidant intake was associated with reduced risk of cognitive decline after the researchers removed factors relating to exercise, alcohol intake, calories, gender, age, education and obesity. Other research has shown that obesity, smoking and lack of exercise all increase the rate of cognitive decline.

What this all means is that mental disorders are no longer conditions that necessarily fall neatly within the abstract domain of behavioral psychology and psychiatry. Rather, recent research suggests that poor diets and poor lifestyles likely contribute significantly to the development of mental disorders, which are thus, to a great degree, preventable. In other words, such research brings mental disorders within the realm of natural health and nutrition. What is now known is that a person with a healthy diet containing plenty of antioxidants, together with an active lifestyle, has a significantly reduced risk of having a mental disorder. More importantly, a person with a healthier, antioxidant-rich diet will also stand a better chance of remaining alert into their elderly years.