Environmental: Children whose mothers consumed alcohol, used illegal drugs or smoked during pregnancy have higher frequency of Attention deficit Disorder. Exposure to toxic metals, such as lead, mercury, and cadmium and synthetic poisons, especially pesticides is associated with an increased risk of developing ADD. Toxins produced by household mold may also lead to nervous system abnormalities and brain damage, which can manifest similar to this condition.
Hormonal: Adrenal hormone imbalances, abnormal (usually high) blood sugar levels and thyroid hormone imbalances can cause inattentiveness.
Immune: There is a strong evidence that neurotransmitter imbalances may be caused by inflammation, a basic form of immune response. Inflammatory reactions produce chemicals called cytokines, which alter function of many cells, including brain neurons. Recently studies have suggested the involvement of cytokine pathways in patients with ADHD.
Allergic: Children with attention deficit are several times more likely to have food allergies than the general population. Food allergies, especially allergies to gluten may play a role through the production of high amounts of cytokines ( substances often causing inflammation).
Genetic: Attention disorders have a tendency to run in families. A few genes have been pinpointed, making a child with family members with ADHD to be at a greater risk than the general population.
Neurologic and Psychiatric: Neurologic conditions, including traumatic and hypoxic brain injury, seizure, stroke, encephalitis, meningitis, spina bifida and many others are associated with ADD as well as some developmental and psychiatric conditions including depression, hearing and visual impairment and conduct disorder. Patients with ADHD may have smaller brain volume and fewer nerve cell connections in the brain, further impairing the ability of the neurotransmitters to function properly.
Nutritional: Dietary deficiencies of amino acids, omega 3 fatty acids, vitamin B6, calcium, iron, magnesium, selenium, iodine and zinc, excessive amounts of refined sugar and artificial food additives may contribute to the symptoms.
Infectious diseases: Many viruses, including influenza, enteroviruses and varicella can occasionally cause encephalitis (brain infection) with subsequent brain injury, otitis media (ear infection), Lime disease and streptococcal infections which can lead to the symptoms of ADHD.
It is presumed that in most cases genetically determined low dopamine brain production is the primary cause of ADHD with a multitude of other factors being secondary causes.