Brain

The brain is a pinkish-grey, wrinkled organ that fills the skull — looking, for all the world, like a huge walnut. It is hard to believe, from its appearance, that this ugly lump of jelly contains the mechanisms of thought, perception, will, and consciousness, that it is the seat of our personality. Its 100,000 million nerve cells, each with an average of 100,00 connections from other neurons, makes the human brain the most complicated and least understood object in the known universe. The vertebrate brain is the large anterior portion of the central nervous system . The "cranial vault" of the skull encases the brain in most vertebrates. In invertebrates, the enlarged and specialized anterior ganglion of the central nervous system is often referred to as a brain, although not all scientists regard it as a true brain.

Cognitive dysfunction

Cognitive dysfunction (also known as brain fog) is the loss of intellectual functions such as thinking, remembering, and reasoning of sufficient severity to interfere with daily functioning. Patients with cognitive dysfunction have trouble with verbal recall, basic arithmetic, and concentration.
According to the Marshall Pathogenesis, cognitive dysfunction is caused by microbes. More severe forms of cognitive dysfunction are seen in diseases such as Alzheimer's, diseases for which there is strong evidence of a bacterial etiology. Often associated with chronic fatigue syndrome, cognitive dysfunction is also seen in patients with multiple sclerosis, depression, fibromyalgia, and dozens of others diseases.