Some major principles underlying brain diseases:
Our brain is a very complex - if not the most complex - organ. It enables us to receive information about our environment, to process it, to generalize and make predictions about future events, and to control the many different effectors (muscles, secretory glands, etc.) that build up our body, all with the ultimate goal of increasing the likelihood of survival.
Every disease that we know is very probably the result of two different factors that interact with each other: genetic and environmental influences. For example, some subtypes of Alzheimer's disease (called familial forms) have a strong genetic basis that seems to leave not much space for environmental influences (almost everyone that "has the gene" will develop the disease with a very high probability at a certain age). On the other hand, other forms (called sporadic forms) seem to have only a weak genetic basis, strongly suggesting that - although genetic predisposition may play an important role (meaning that some people have a relatively high risk of developing the disease up to a certain age) - environmental influences (like the way of life in general, contact with certain substances, nutrition, psychological well-being, and/or many other factors) may be more important.
In the past decade, researchers have been able to find thousands of so-called 'disease genes, which are units of inheritance that - in a certain form - increase the risk of getting a particular disease. Gene therapy- in spite of some setbacks - may finally provide help for patients that have a disease-causing gene defect.
In those cases where environmental influences dominate, it is sometimes more important to find out at which time they take effect, rather than to discriminate between the millions of hard-to-distinguish factors in our environment. For example, some researchers think that in a proportion of schizophrenic patients there have been different environmental influences before birth (such as viral infections, excessive radiation or contact with toxic substances) that resulted in very similar disturbances of normal brain development. During early stages of brain development, the "brain seems to wire itself", meaning that the connections between neurons that later guarantee the processing of information are established. If there are any environmental influences during this phase that disturb processes involved in normal brain development (for example, the migration of neurons from their place of birth to their final destination, or the development of neuronal contacts called synapses), it is conceivable that there may be wrong connections that subsequently or later result in inappropriate brain function (mental retardation, hallucinations, abnormal behavior etc.). In the case of hallucinations, there may be wrong connections between neurons that result in the reception of sensory information that does not exist (loss of contact with reality!).
If we want to develop better treatments for diseases, we have to understand their causes to a certain degree. Recent developments in biological and medical research - mostly related to the fields of functional genomics and protoenomics- may result in much better health care soon because they allow us to have a much deeper look into very complex processes on a molecular and cellular level. You may say that after searching the forest with a torch, the sun is rising, and we now have to learn to interpret what we see.
Sites where you can obtain further information...

                                    Central Nervous System Diseases

                            Infectious Diseases of the Central Nervous System

                                    Chronic Illnesses Net