The Disordered Mind

We all get terribly sad sometimes. Everyone occasionally has wild ideas, strange urges, and moments of anxiety, euphoria, or forgetfulness. But what if we’re sad, euphoric, or forgetful all the time?

When ordinary mental experiences go into overdrive and begin to interfere with our daily lives, they might indicate a mental disorder. Mental disorders such as depression, schizophrenia, or dementia are often characterized by exaggerations of everyday thoughts, feelings, and behavior. When you’re clinically depressed, for example, you don’t feel down occasionally – you feel debilitatingly sad over weeks and months.

The key message here is: Brains that work abnormally can teach us how brains normally work.

Psychiatry, the medical study of mental disorders, was founded by French physician Philippe Pinel in 1790. Pinel was the first scientist to suggest that mental disorders have a physical basis.

Today, we know that all mental disorders are also disorders of the brain. Genetic defects, environmental factors, or injury can change the brain’s normal structure and functioning. Because there’s a direct link between these physical changes and their effect on a person’s thoughts, feelings, and behavior, mental disorders reveal a lot about how our brains work.

Before we dive into this field of study, let’s go over some basics. The brain is made up of millions of specialized nerve cells called neurons that form intricate networks to pass information between our brain, body, and senses, which give rise to our mental processes. Neurons communicate with each other through a system of electrical signals, and chemical molecules called neurotransmitters. In many mental disorders, certain networks of neurons become dysfunctional, hyperactive, or unable to communicate.

Modern neuroscience studies why and how this happens, using the latest scientific technologies. For example, scientists can now alter, delete, or insert certain genes in mice to learn how these genes affect the brain. Thanks to such animal models, we now know that there’s simple genetic disorders of the brain like Huntington’s that are caused by a single mutated gene, and complex genetic disorders like depression that involve multiple genes and environmental factors.

In addition, modern brain imaging techniques allow neuroscientists to study the activity of the brain in action. An fMRI, for instance, measures changes in the concentration of oxygen in red blood cells to determine which parts of the brain are active at any given moment. Equipped with these technologies, the study of brain disorders is shining a light into the healthy brain.