Restricted and repetitive patterns of behavior, interests, or activities. Repetitive and stereotyped patterns also include intense adherence to routine and self-injurious behavior. Infants with ASD lack social interest, do not play interactive or imitative games, are extremely sensitive to touch and sound, and have abnormal sleep patterns. They have rigid eating patterns, like refusing to eat certain foods because of the smell, texture, or taste. Some of these children may also have IQs below 70. Behavioral problems such as hyperactivity, impulsivity, social anxiety, general anxiety, irritability, and aggression are common, as are depression and phobia. ADHD is considered a neurodevelopmental disorder with genetic, biological, and environmental influences. Like many other disorders, ADHD runs in families. Twin studies support its heritability. To date, genetic studies have identified at least seven different genes that may associate with ADHD. MRI studies reveal abnormalities in the frontal cortex, cerebellum, and subcortex when children with ADHD are compared with children who do not have this disorder. Other potential contributory factors include lead contamination, maternal smoking and/or alcohol use during pregnancy, pregnancy and delivery complications, and psychological risk factors such as marital discord, low socioeconomic status, large family size, and maternal psychological problems. Delirium is associated with a range of biological and environmental factors, but it is more often brought on by a serious medical illness, such as AIDS, congestive heart failure, infection, or toxic effects of a medication. Other biological causes of delirium include metabolic disorders, neurological disorders (such as head trauma, stroke, seizures, and meningitis), malnutrition, and alcohol or drug intoxication. The risk of delirium increases with age and cognitive impairment. Delirium is associated with dysfunction of prefrontal cortex, thalamus, and basal ganglia. Also, a number of neurotransmitters may be involved such as dopamine and serotonin Named after it's discoverer, Alois Alzheimer, Alzheimer's Disease is the most common subtype of neurocognitive disorder, accounting for about 75% of all patients. It has a slow and progressive course of cognitive decline. The first noticeable signs include forgetting recent events or names, repeating statements or questions, getting lost while driving in familiar places, and experiencing difficulty with calculations. Many of such patients are able to maintain a positive quality of life for some years after diagnosis. This disease results in more severe impairments in the ability to use language, make decisions, and engage in self-care. Behavioral problems also occur and include disrupted sleep, wandering, irritability, and aggression. The rate of progressive deterioration in cognitive capabilities and functioning increases as the severity of the disease worsens. Diagnosed when a patient's history, laboratory tests, and/or brain imaging studies indicate cognitive impairment as a result of cardiovascular disease such as stroke, transient ischemic attack, coronary artery disease, or untreated high blood pressure. In these conditions, blockages of blood vessels result in tissue death (infarction) in the brain. Damage may be to a single major vessel or lots of smaller ones. Vascular neurocognitive disorder has different clinical features than Alzhiemer's. Substance use, particularly alcohol-related disorder, can lead to dementia that is difficult to differentiate from Alzheimer's. Substance use may also increase vulnerability to other forms of dementia and for other contributing factors such as head trauma, infectious disease, and vitamin deficiency. Major and mild neurocognitive disorder occurs in five to ten percent of adults age 65 and over. Alzheimer's disease is the most common type, diagnosed in up to 75% of cases. Unfortunately, many patients with neurocognitive disorders remain undiagnosed and untreated. The impact of neurocognitive disorders on patients, their families, and the healt