Mental disorders (or mental illnesses) are conditions that affect your thinking, feeling, mood, and behavior. They may happen over a short period of time or come and go. Some can be chronic (long-lasting). They can affect your ability to relate to others and function each day..

There are many different types of mental disorders. Some common ones include:

• Anxiety disorders, including panic disorder, obsessive-compulsive disorder, and phobias
• Depression, bipolar disorder, and other mood disorders
• Eating disorders
• Personality disorders
• Post-traumatic stress disorder (PTSD)
• Psychotic disorders, including schizophrenia

There is no single cause for mental illness. A number of factors can contribute to risk for mental illness, such as:

• Your genes and family history
• Your life experiences, such as stress or a history of abuse, especially if they happen in childhood
• Biological factors such as chemical imbalances in the brain
• A traumatic brain injury (TBI)
• Prenatal (before birth) exposure to viruses, toxic chemicals, or other substances such as alcohol and drugs.
• Use of alcohol or recreational drugs
• Having a serious medical condition like cancer
• Having few friends, and feeling lonely or isolated

Mental disorders are not caused by character flaws. They have nothing to do with being lazy or weak.

Mental disorders are common. Many Americans will be diagnosed with a mental disorder at some time in their life.

The steps to getting a diagnosis include:

• A medical history
• A physical exam and possibly lab tests, if your provider thinks that other medical conditions could be causing your symptoms
• A psychological evaluation. You will answer questions about your thinking, feelings, and behaviors.

Treatment depends on which mental disorder you have and how serious it is. You and your provider will work on a treatment plan just for you. It usually involves some type of therapy. You may also take medicines. Some people also need social support and education on managing their condition.

In some cases, you may need more intensive treatment. You may need to go to a psychiatric hospital. This could be because your mental illness is severe. Or it could be because you are at risk of hurting yourself or someone else. In the hospital, you will get counseling, group discussions, and activities with mental health professionals and other patients.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a serious, long-term illness that affects many body systems. Another name for it is chronic fatigue syndrome (CFS). ME/CFS can often make you unable to do your usual activities. Sometimes you may not even be able to get out of bed.

Researchers don't yet know what causes ME/CFS. There may be more than one potential cause. It is also possible that two or more triggers might work together to cause the illness.

Researchers are studying many possible causes, including:

• Infections
• Immune system changes
• Physical or emotional stress
• Changes in the way cells in the body get their energy
• Genetics; the illness can sometimes run in families

Anyone can get ME/CFS, but it is most common in people between 40 and 60 years old. Adult women are more likely to develop it than adult men.

The primary, or core, symptoms of ME/CFS are:

• Not being able to do activities that you used to do before the illness, along with severe fatigue. The fatigue must last six months or longer, and it is not improved by rest.
• Post-exertional malaise (PEM), which means that your symptoms get worse after any physical or mental activity.
• Sleep problems.

Along with the primary symptoms, to be diagnosed with ME/CFS, you need to have one or both of these symptoms:

• Problems with thinking and memory.
• Worsening of symptoms while standing or sitting upright. This is called orthostatic intolerance. It can cause you to feel lightheaded, dizzy, weak, or faint while standing or sitting up.

Some of the other symptoms that ME/CFS can cause include:

• Pain, including muscle pain, joint pain, and headaches
• Sore throat
• Tender lymph nodes (glands) in the neck or armpits
• Digestive issues, like irritable bowel syndrome
• Chills and night sweats
• Allergies and sensitivities to foods, odors, chemicals, light, or noise

ME/CFS can be unpredictable. Your symptoms may come and go. They may change over time; sometimes they might get better, and other times they may get worse.

ME/CFS can be difficult to diagnose. There is no specific test for ME/CFS, and other illnesses can cause similar symptoms. Your health care provider has to rule out other diseases before making a diagnosis of ME/CFS.

Your provider will do a thorough medical exam, which will include:

• Asking about your medical history and your family's medical history.
• Asking about your current illness, including your symptoms. Some questions they may ask could include how often you have symptoms, how bad they are, how long they have lasted, and how they affect your life.
• Thorough physical and mental status exams.
• Blood, urine, or other tests to check for other illnesses which could be causing your symptoms.

Your provider may also ask you to see a specialist to check for other conditions which can cause similar symptoms.

There is no cure or approved treatment for ME/CFS, but you may be able to treat or manage some of your symptoms.

You, your family, and your provider should work together to decide on a plan. You should figure out which symptom causes you the most problems and try to treat that first. For example, if sleep problems affect you the most, you might first try using good sleep habits. If those do not help, you may need to take medicines or see a sleep specialist.

Strategies such as learning new ways to manage activity can also be helpful. You need to make sure that you do not "push and crash." This can happen when you feel better, do too much, and then get worse again.

When you have ME/CFS, it can be hard to help develop a treatment plan. It can also be difficult to try to take care of yourself. So it's important that you have support from family members and friends.

There are also various resources and strategies that might be helpful to you, such as:

• Getting counseling to help you cope with the illness and its impact on your life.
• Eating a healthy diet.
• Nutritional supplements, if your provider suggests them.
• Complementary therapies such as meditation, gentle massage, or relaxation therapy.

Make sure to talk to your provider before you try any new treatments. Some treatments that are promoted as cures for ME/CFS are unproven, often costly, and could be dangerous.

Centers for Disease Control and Prevention

The optic nerve is a bundle of more than 1 million nerve fibers that carry visual messages. You have one connecting the back of each eye (your retina) to your brain. Damage to an optic nerve can cause vision loss. The type of vision loss and how severe it is depends on where the damage occurs. It may affect one or both eyes.

There are many different types of optic nerve disorders, including:

• Glaucoma is a group of diseases that are the leading cause of blindness in the United States. Glaucoma usually happens when the fluid pressure inside the eyes slowly rises and damages the optic nerve.
• Optic neuritis is an inflammation of the optic nerve. Causes include infections and immune-related illnesses such as multiple sclerosis. Sometimes the cause is unknown.
• Optic nerve atrophy is damage to the optic nerve. Causes include poor blood flow to the eye, disease, trauma, or exposure to toxic substances.
• Optic nerve head drusen are pockets of protein and calcium salts that build up in the optic nerve over time

Contact your health care provider if you are having vision problems. Tests for optic nerve disorders may include eye exams, ophthalmoscopy (an examination of the back of your eye), and imaging tests. Treatment depends on which disorder that you have. With some optic nerve disorders, you may get your vision back. With others, there is no treatment, or treatment may only prevent further vision loss.

Almost 1 of every 10 infants born in the United States are premature, or preemies. A premature birth is when a baby is born before 37 completed weeks of pregnancy. A full-term pregnancy is 40 weeks.

Important growth and development happen throughout pregnancy - especially in the final months and weeks. Because they are born too early, preemies weigh much less than full-term babies. They may have health problems because their organs did not have enough time to develop. Problems that a baby born too early may have include:

• Breathing problems
• Feeding difficulties
• Cerebral palsy
• Developmental delay
• Vision problems
• Hearing problems

Preemies need special medical care in a neonatal intensive care unit, or NICU. They stay there until their organ systems can work on their own.

Centers for Disease Control and Prevention

Sciatica is a symptom of a problem with the sciatic nerve, the largest nerve in the body. It controls muscles in the back of your knee and lower leg and provides feeling to the back of your thigh, part of your lower leg, and the sole of your foot. When you have sciatica, you have pain, weakness, numbness, or tingling. It can start in the lower back and extend down your leg to your calf, foot, or even your toes. It's usually on only one side of your body.

Causes of sciatica include:

• A ruptured intervertebral disk
• Narrowing of the spinal canal that puts pressure on the nerve, called spinal stenosis
• An injury such as a pelvic fracture.

In many cases no cause can be found.

Sometimes sciatica goes away on its own. Treatment, if needed, depends on the cause of the problem. It may include exercises, medicines, and surgery.