Mental disorders are any kind of thinking problem that takes someone beyond the boundaries of accepted norms. In order for something to be classified as a mental disorder, it usually also has to have a negative impact on some aspect of a person’s life. Generally, each separate mental disorder has its own standardized collection of symptoms that doctors use to make a diagnosis. Mental disorders can be related to actual physical problems with the brain, such as chemical imbalances, or they can be reactions to certain life experiences.
One of the main things that separates a mental disorder from most normal mental difficulties is severity. According to most experts, a mental disorder shouldn’t be diagnosed if the problems aren’t severe enough to interrupt a person’s normal daily function in some way. For example, many people may be afraid of spiders, but they would normally only receive a diagnosis for arachnophobia if that fear was extreme enough to cause problems.
Some mental disorders are present from birth. These often include psychosis-oriented diseases like schizophrenia, along with other disorders related to compulsions. Some of these diseases are caused by actual brain damage, while chemical regulation processes cause others, but generally speaking, all of them are related to physiology.
Some other mental disorders are related to emotional problems. For example, people may have major behavior changes after going through certain extreme events, such as wars or abuse. Other people may have a temperament that makes them prone to certain disorders and then have life experiences that actually trigger the onset of these problems.
There is a large book called the "Diagnostic and Statistical Manual" that is used for official classification of each mental disorder. This book is updated periodically to reflect different diagnostic options for psychological doctors based on new research. Sometimes a small change in the book can lead to major changes in the way patients are diagnosed or treated.
In a few cases, these changes can be somewhat negative because doctors can occasionally jump on the bandwagon of a particular diagnosis unnecessarily. For example, some people believe that Asperger’s syndrome is diagnosed much too frequently. When it was initially added to the manual, the disorder was studied and experts suggest that it was very rare, but after being added, doctors started diagnosing it constantly to the point where many people feel it was being overused.