Brain diseases come in different forms. Infections, trauma, stroke, seizures, and tumors are some of the major categories of brain diseases. Here's an overview of various diseases of the brain.

Meningitis: An inflammation of the lining around the brain or spinal cord, usually due to infection; Neck stiffness, headache, fever, and confusion are common symptoms.

Encephalitis: An inflammation of the brain tissue, usually due to a viral infection; meningitis and encephalitis often occur together, which is called meningoencephalitis.

Brain abscess: A pocket of infection in the brain, usually caused by bacteria.

Included in the seizure category of brain diseases is epilepsy, a condition characterised by recurring seizures caused by abnormal and excessive electrical activity in the brain. Head injuries, brain infections, and strokes may cause epilepsy, as well.

Trauma includes these conditions:

Concussion: A brain injury that causes a temporary disturbance in brain function, sometimes with unconsciousness and confusion; traumatic head injuries cause concussions and may result in headache, along with concentration and memory problems.

Traumatic brain injury: Acquired, often permanent brain damage from a traumatic head injury; obvious mental impairment or more subtle personality and mood changes can occur.

This category of brain disease includes:

Brain tumor: Any abnormal tissue growth inside the brain; whether malignant (cancerous) or benign, brain tumors usually cause problems by the pressure they exert on the normal brain.

Glioblastoma: An aggressive, cancerous brain tumor; glioblastomas progress rapidly and are usually difficult to cure.

Hydrocephalus: An abnormally increased amount of cerebrospinal (brain) fluid inside the skull; usually, this is because the fluid is not circulating properly.

Normal pressure hydrocephalus: A form of hydrocephalus that often causes problems with walking, along with dementia and urinary incontinence; pressure inside the brain remains normal, despite the increased fluid.

Pseudotumor cerebri (false brain tumor): Increased pressure inside the skull with no apparent cause (although it is associated with obesity or weight gain); vision changes, headaches, dizziness, and nausea are common symptoms. It could also lead to blindness.

Brain diseases connected with blood vessel conditions include:

Stroke: Blood flow and oxygen are suddenly interrupted to an area of brain tissue, which then begins to die. The body part controlled by the damaged brain area (such as an arm or a leg) may no longer function properly. Stroke may cause vision, speech and sensation problems.

Ischemic stroke: A blood clot suddenly develops in an artery or is formed elsewhere in another artery and breaks off and lodges in the brain blood vessels, blocking blood flow and causing a stroke.

Hemorrhagic stroke:Bleeding in the brain creates congestion and pressure on brain tissue, impairing healthy blood flow and causing a stroke.

Cerebrovascular accident (CVA): Another name for stroke.

Transient ischemic attack (TIA): A temporary interruption of blood flow and oxygen to a part of the brain; symptoms are similar to those of a stroke, but they resolve completely (usually within 24 hours) without damage to brain tissue.

Brain aneurysm: An artery in the brain develops a weak area that swells like a balloon. A brain aneurysm rupture causes a stroke, due to bleeding.

Subdural hematoma: Bleeding on the surface of the brain; a subdural hematoma may exert pressure on the brain, causing neurological problems.

Epidural hematoma: Bleeding between the skull and tough (dura) lining of the brain; the bleeding is typically from an artery, usually shortly after a head injury. Initial mild symptoms can progress rapidly to unconsciousness and death, if untreated. This is also referred to as an extradural hematoma.

Intracerebral hemorrhage: Any bleeding inside the brain, which may occur after a traumatic injury or stroke as a result of high blood pressure

Cerebral edema: Swelling of the brain tissue which can be due to different causes, including response to injury or electrolyte imbalance

Brain diseases linked to autoimmune conditions include:

Vasculitis: An inflammation of the blood vessels of the brain; confusion, seizures, headaches, and unconsciousness can result.

Multiple sclerosis (MS): The immune system mistakenly attacks and damages the body's own nerves. Muscle spasm, fatigue, and weakness are symptoms. MS may occur in periodic attacks or be steadily progressive.

Brain diseases linked to neurodegenerative conditions include:

Parkinson's disease: Nerves in a central area of the brain degenerate slowly, causing problems with movement and coordination. Early signs are a tremor of the hands, stiffness of the limbs and trunk, slowness of movement, and unstable posture.

Huntington's disease: An inherited nerve disorder that causes a degeneration of brain cells; dementia and difficulty controlling movements (chorea) are its symptoms. Early signs include mood swings, depression, and irritability.

Pick's disease (frontotemporal dementia): Over years, large areas of nerves at the front and sides of the brain are destroyed, due to buildup of an abnormal protein. Personality changes, inappropriate behavior, difficulty with speech, and loss of memory and intellectual ability are symptoms. Pick's disease is steadily progressive.

Amyotrophic lateral sclerosis (ALS): ALS is also called Lou Gehrig's disease. In ALS, nerves controlling muscle function are steadily and rapidly destroyed. ALS steadily progresses to paralysis and inability to breathe without mechanical assistance. Cognitive function is generally not affected.

Dementia: A decline in cognitive function, due to death or malfunction of nerve cells in the brain; conditions in which nerves in the brain degenerate, as well as alcohol abuse and strokes, can cause dementia.

Alzheimer's disease: For unclear reasons, nerves in certain brain areas degenerate, causing progressive loss of memory and mental function, and changes in behavior and personality. The buildup of abnormal tissue in brain areas -- often called tangles and plaques -- is believed to contribute to the disease. Alzheimer's disease is the most common form of dementia.