Doctors are getting a much better understanding of the causes of mental illness and other brain disorders. Researchers, for the first time, are discovering the genes that are active in different types of common neurologic diseases.
Let’s first review some common neurologic disorders:
- Schizophrenia: a long-term mental disorder of a type involving a breakdown in the relation between thought, emotion and behavior, leading to faulty perception, inappropriate actions and feelings, withdrawal from reality and personal relationships into fantasy and delusion, and a sense of mental fragmentation.
- Alzheimer’s disease: a progressive mental deterioration that can occur in middle or old age due to generalized degeneration of the brain. It is the most common cause of premature senility.
- Bipolar affective disorders: a mental disorder marked by alternating periods of elation and depression.
- Alcoholism: an addiction to the consumption of alcoholic liquor or the mental illness and compulsive behavior resulting from alcohol dependency.
- Autism: a mental condition, present from early childhood, characterized by difficulty in communicating and forming relationships with other people and in using language and abstract concepts.
- Parkinson’s disease: a progressive disease of the nervous system marked by tremor, muscular rigidity, and slow, imprecise movement, chiefly affecting middle-aged and elderly people. It is associated with degeneration of the basal ganglia of the brain and a deficiency of the neurotransmitter dopamine.
- Depression or depressive disorder: a mental condition characterized by feelings of severe despondency and dejection, typically also with feelings of inadequacy and guilt, often accompanied by lack of energy and disturbance of appetite and sleep.
Research scientists have come to a better understanding of many brain (neurologic) conditions and diseases that were common, yet poorly understood. These disorders include the likes of depression, autism, bipolar disorder, schizophrenia and alcoholism.
Unlike other neurologic conditions like Parkinson’s disease or Alzheimer’s disease, many neurologic conditions were classified and diagnosed based on a patient’s behavior. If one looked at their brains, there were no apparent changes.
In Parkinson’s and Alzheimer’s, the analysis of brain tissue shows remarkable differences from those of healthy brains, so that these conditions can be diagnosed anatomically by just looking at them, and not just based on a patients behavior. In these diseases, the brain demonstrates obvious and dramatic physical changes.
Fortunately, doctors’ understanding of the causes of mental illness and other brain disorders is rapidly improving. In a recently published report in the journal Science, Dr. Geschwind and colleagues at UCLA decided to evaluate diseased brains not by how they look at autopsy, but rather by what was happening in the brain cells when they had a specific disease. Scientists can do this by looking at what genes are turned on and what genes are turned off inside brain cells.
Humans have about 25,000 different genes. All 25,000 genes are contained in (almost) every human cell. The reason why a kidney cell is entirely different from a muscle cell is in what genes are turned on and what genes are turned off. Scientists call this “gene expression.”
The reason we have different tissues and organs in the human body depends entirely on the gene expression in that organ. That is why the heart and brain are completely different.
(Technically, scientists measure gene expression by analyzing different types of RNA, produced by genes, inside brain cells.)
Scientists are now looking at the gene expression patterns in brain diseases like autism, depression, schizophrenia and bipolar disorder, and they have made some fantastic discoveries. Many brain disorders have similar patterns of gene expression.
Interestingly, in addition to similar patterns of gene expression, they also have unique patterns of gene expression that may allow, for the first time, to better diagnose brain diseases based on what is happening inside the brain cells at the molecular level instead of relying solely on the way a patient is behaving.
The molecular gene expression is a new “signature of a disease” and is a breakthrough for doctors to assist in diagnosing neurologic disorders and mental illness. As a result, scientists can develop new research programs for better future treatments.
Although very promising, this research will take some time to become available for daily use by doctors. This study looked at the gene activity of brains in deceased patients. It is now essential to be able to transfer this research into evaluating gene expression in living patients.
This brain disorder research is just a first, yet monumentally critical step in the better diagnosis and treatment of devastating neurologic diseases that affect so many people. Kenneth Kendler, a psychiatrist and geneticist at Virginia Commonwealth University, commented: “This [research] is changing fundamental views about the nature of mental and psychiatric illness.”
As a result, the future appears very bright when it comes to a better diagnosis of and treatment for mental illness and brain diseases.
Source: NPR, Science. Reference: American Academy of Dermatology