Disorders of the Brain.
Neurotransmitters play a major role in controlling state of mind, ie consciousness, emotions and behaviour. Even slight changes to the neurotransmitter systems can contribute to the development of neurological problems or brain disorders. Understanding how circuits, synapses and neurotransmitters are altered in people with brain disorders is critical in the development of new treatments and prevention strategies, aimed at relieving the distress caused by potentially severely debilitating illnesses.
The complexity of the brain does not end with its structural and chemical composition. The brain is a dynamic organ and is in a constant state of change, governed by life experiences. Every time we learn something new, form a memory, experience stress or disease, the biochemical structure of our brain changes at the neuronal level. This affects information flow and is known as neuronal plasticity.
The brain is very complex, and the symptoms of many brain disorders are heterogeneous and often diverse. Classification systems have been developed by panels of experts to enable clinicians to make accurate diagnoses of brain disorders. Using these classification systems, the symptoms of disorders are clearly defined and grouped.
For the classification of psychiatric disorders, there are two systems commonly used worldwide. The first one, developed by the American Psychiatric Association is the Diagnostic and Statistical Manual of Mental Disorders (DSM), and is mainly used in the USA. The second, which is more widely used across Europe, is the International Classification of Diseases, Part 10 (ICD-10). Both systems are curently under review and will be published as the DSM-V and te ICD-11.
Using these guidelines, it is possible to determine which mental illness an individual may have and rule out others which may have overlapping symptoms.
Factsheet: Rating scales.
The impact of the environment and our experiences on our state of mind is better understood now than in the past, and this increased knowledge has significantly changed the way several brain disorders are managed and treated. Psychotherapy is now recognised as an important component of the treatment of people with psychiatric and psychological disorders. A combination of non-pharmacological and pharmacological therapy is usually the most effective treatment option for these people. Psychoeducation should also be recognised as an important component of disease management, and this can be directed not only towards the person with the illness but also their family or friends.
There are a number of different psychotherapeutic approaches that are appropriate to different neurological disorders. Common psychotherapeutic approaches include psychoeducation, cognitive behavioural therapy (CBT), family interventions, group therapy and therapy specific to an individual case, such as therapy for substance abuse.Read more about psychotherapy.
Psychotropic drugs selectively affect one or more steps in the synthesis, packaging, release, action or degradation of a neurotransmitter. Determining the mechanism of action of many psychotropic drugs has facilitated understanding of the molecular mechanisms that underlie some diseases.
Psychotropic drugs exert their effects in a number of ways. These include:
Psychotropic drugs can affect the synthesis, storage, release and reuptake of neurotransmitters and may suppress or enhance neurotransmitter action. Several different types of antidepressant drugs are reuptake inhibitors of serotonin, noradrenaline or both.
The majority of psychotropic drugs act to modify synaptic transmission by either activating or inhibiting postsynaptic receptors. These drugs are known as agonists and antagonists, respectively. An agonist inhibits or blocks the action of a neurotransmitter, often by binding to the receptor and preventing the natural transmitter from binding there. An antagonist, on the other hand, disrupts the action of the neurotransmitter.
A mechanism which appears to have a key role in the long-term effects of some psychotropic drugs is receptor adaptation. Many drugs, such as antidepressants, require chronic or long-term administration to produce a therapeutic effect and this may be due to subtle changes in receptor function that occur secondarily to their initial biochemical effects.
The two major enzymes concerned with the catabolism of ‘classical’ neurotransmitters are monoamine oxidase and acetylcholinesterase. These enzymes are involved with the catabolism of biogenic amines, such as serotonin, noradrenaline, dopamine and acetylcholine. Inhibition of these enzymes leads to an increase in the concentrations and activities of the relevant neurotransmitters.
Explore the following brain disorders and find out how the brain is affected by each illness:
Last updated: 20.12.2011