Organic Illness

Mental disorders have been classified by various organizations, including the World Health Organization (WHO) and American Psychiatric Association (APA). Though, there is no universally accepted list, those made by the WHO and APA are widely used. 

The following are some of the common mental disorders and are called as Organic Brain Disorders/ Diseases/ Syndromes .Organic type is used to denote physical disorders than can lead to mental illnesses and not the psychiatric ones. However, the demarcation between the two is almost impossible in many cases. So, this term is not widely used nowadays. 

1. Huntington disease - an inherited disease that affects the brain. It causes progressive breakdown of the nerve cells in the brain, leading to functional, cognitive and psychiatric problems.
2. Multiple sclerosis - another degenerative disease that affects the myelin sheath covering of the nerve cells, thereby slowing down or stopping the nerve impulses. This disorder affects the central nervous system (brain & spinal cord), causing a wide range of physical as well as mental symptoms.
3. Alzheimer's disease - one of the common causes of dementia (loss of brain function caused by certain diseases).Alzheimer's disease is characterized by degeneration and death of brain cells, thereby affecting the mental function.
4. Parkinson's Disease - a degenerative disorder of the central nervous system. This condition affects the nerve cells' ability to send messages and cause tremors that may even lead to paralysis.

There are various cardiovascular diseases that may affect the functioning of the brain and lead to certain mental illnesses. These include stroke, cardiac arrhythmias, infections of the heart, etc.
Sometimes mental disorders can be trauma-induced. For example, a head injury can affect the brain and cause damage to the organ, causing mental disorders.

There are various other conditions that can affect brain functioning. They include medical conditions like cancer, thyroid problems, liver and kidney diseases, infections (like septicemia), certain vitamin deficiencies (like B12), drug and alcohol related - intoxication, drug and alcohol withdrawal symptoms, etc.

Source: www.buzzle.com

(This  is for information only. Take the advice of your physician for treatment.)