Brain inflammation, or neuroinflammation, is associated with significant risk for various degenerative brain diseases, including Alzheimer’s and other dementias. It rapidly ages the brain, altering brain function and destroying brain tissue similar to how chronic joint inflammation can destroy joint tissue, leading to joint deformity, stiffness and pain.
There are both immediate and long term complications of neuroinflammation.  Short term consequences are that it immediately hinders the transmission speed and conductivity of neurons, which means neurons fire more slowly. This slows down brain function and creates symptoms of brain fog, slower mental speed, slower recall and slower reflexes. Another immediate consequence is that it shuts down energy production in the cells so that brain endurance plummets. This causes limited endurance for mental tasks and may also cause depression. A longer term consequence of chronic neuroinflammation is neuron death and the development of neurogenerative disorders.
Inflammation in the brain can be triggered by inflammation elsewhere in the body, such as infection, inflammatory bowel disease, or an unmanaged autoimmune condition. These issues cause the body to release immune messengers called cytokines that reach the brain in various ways (including directly crossing the blood brain barrier), thereby activating inflammation.       Likewise, inflammation or degeneration in the brain can activate the body’s immune system and trigger systemic inflammation, referred to as neurogenic inflammation. 
The brain’s immune system
At the root of brain inflammation are microglia cells, the brain’s immune soldiers. There are 10 glia cells for every neuron in the brain, and if you weigh the brain, more than 50% of it is glia cells - in other words, the brain is more glia cells than neurons.
Microglia cells are either in a resting state or an active state. In normal conditions the microglia perform many functions vital for healthy brain function. They dispose of dead neurons, beta amyloid plaque (the substance that predisposes one to Alzheimer’s), and other cellular debris that can interfere with healthy communication between neurons. However, in a heightened state of activation, they create an overzealous immune response that causes brain inflammation.
Several factors increase the risk of activating brain microglia:         
- Diabetes and high carb diets, which lead to the production of glycosated end products that activate microglia cells
- Lack of oxygen from poor circulation, lack of exercise, chronic stress response, heart failure, lung disorder, or anemia
- Head trauma
- Autoimmune reaction to neurological tissue
- Gluten, especially for those who are intolerant
- Low brain antioxidant status
- Alcohol and drug abuse
- Environmental toxins
- Systemic inflammation
- A compromised blood brain barrier