ADHD: Causes, Role of Genetics, Gut, Diet and Treatment
ADHD is a problem mainly seen during childhood but may persist into adult life in a large number of cases. Patients have high degree of hyperactivity, inattentiveness, impulsivity. Usually the kid has a combination of these in varying proporttions. Of course, many of these are part of growing up processes, as such the diagnosis is only made when the severity of manifestations is out of bounds with child's age and developmental stage.
Prevelance of ADHD
ADHD is not just the most common behavioral disorder seen during childhood but actually is the most common disorder among kids, period! The estimates of prevelance vary from 2-18% depending on criteria used and population studied. The best estimate indicate that it affects 3 - 10% of school aged children. As many as 60% may be under some kind of treatment at any given time.
ADHD is rising
It is disoncerting that the prevalence estimates appear to be rising. There was a 9.5% increase in ADHD from 2003 to 2007 based on National Survey of Childrens' Health (NSCH). Whether it is a true increase or merely an increased diagnosis due to increased awareness remains to be established.
ADHD and Age
The prevelance inreases with increasing age. For example, while it is 6.6% among 4 to 10 year old children, the prevelance rises to 13.6 among 15 to 17 year olds.
Gender differences in ADHD
ADHD is more common among boys. The ratio depends upon predominant manifestation. For example, it is 4 times more common among boys for predominantly hyperactivity type as compared to 2-times more common for inattentive ones.
Is ADHD a genetic disorder?
There appears to be a genetic predisposition. There is over 90% concordance in monozygotic and 33% concordance among dizygotic twins. Alterations in a number of genes have been identified and including but limited to those affecting dopamine, serotonin and glutamate receptors.
Imaging studies demonstrate significant structural differences in various areas of the brain of ADHD as compared to controls. It is thus not surprising that functional brain imaging reveals commensurate differences as well including reduced global as well as local activation in basal ganglia and anterior frontal lobe. There appears to be cingulate, frontal and parietal cortical dysfunction in ADHD.
Similarly the response of different regions of brain to the adminstration to pharmacologic agents like methylphenidate is different in ADHD subjects as compared to controls. Depending on the I.Q., there may be different phenotypes of ADHD.
How/Why does ADHD occur?
The precise mechanisms remain to be established. It appears that in an otherwise genetically predisposed individuals, an environmental factor/s sets up processes during critical phase of brain development and the manifestations continue on for a long time, sometimes even into adulthood.
Role of gut in ADHD
Circumstantial evidence suggests that gut bacteria, permeability (leaky gut) along with micronutrient imbalances may play a key role in initiating and/or sustaining the disorder
Role of diet in ADHD
- Dietary factors implicated in the pathogenesis of ADHD include:
- Food additives/preservatives
- Increased sugar intake
- Food allergies and intolerances
- Vitamin, mineral (iron, zinc etc) and essential fatty acid deficiency
- Maladigestion/malabsorption resulting in micronutrient deficiencies
The degree to which one or more of the above dietary factors play a role in ADHD is mired in controversy.
- Smoking or tobaco exposure during pregancy
- Prematurity and low birth infants
- Head injury during early childhood
Differential diagnosis and co-morbidities of ADHD
Most ADHD kids have atleast one additional behavioral/psychological and/or developmental disorder. Conditions below may be confused with or may co-exist in patients with ADHD.
- Learning disabilities
- Anxiety disorder
- Bipolar disorder
- Tic disorders
- Conduct disorder
- Oppositional defiant disorder
Clinical manifestations of ADHD
These can be broadly classified into three categories and the proprtion of each of these categories varies among different patients.
Lack of attention (inattentiveness)
Delayed diagnosis is more likely among patients with predominatly inattentive manifestations since they tend to be less disruptive and so less noticed or less alarming.
Conventional management principles
- Team approach with health care provider, parents or caregivers, and the child is paramount
- Establish specific targeted goals to judge response to specific therapy
- Pharmacologic therapies
- Behavioral therapies
- A combination of drugs and behavioral therapies is most frequent modality
- Lack of response to therapy may require reassesment of diagnosis.
- Needs to be individualized
- UK's National Institute for Health and Clinical Excellence (NICE) guidelines recommed a dietician referral in select cases
Commonly used drugs
- Psychostimulants (also known as stimulants) are most commonly used. Paradoxically, they have a calming effect in patients with ADHD. These include amphetamine-dextroamphetamine, dexmethylphenidate, dextroamphetamine, lisdexamfetamine and methylphenidate.
- Nonstimulant drug rug options include atomoxetine with less potential for misuse.
- Talk therapy
- System of rewards and consequences
- Support groups
- Play therapy
- Cognitive behavioral therapy
- Helpful for co-existing conditions since there is no for benefit core manifestations of ADHD
Complimenatry and alternative therapies
Almost two-thirds of patients use CAM therapies including Chinese Herbal Formulations for control of ADHD; however evidence supporting use of some (but not all) of these is lacking.
Prognosis of ADHD
- Long-term, chronic condition
- Data mostly obtained from psychiatric clinics and as such may not be application to ADHD patients at large.
- 50% of subject continue to have problems as adults
- Lower academic accomplishments
- Inappropriately manages cases may progress to drug abuse, difficulties in school and at job, injuries, driving accidents, and frequent altercations with the law.
- Adult patients may develop significant maturity to enhance their coping/adjustment mechanisms and masking difficulties.
US National Library of Medicine recommends following tips for parents:
Communicate regularly with the child's teacher.
Keep a consistent daily schedule, including regular times for homework, meals, and outdoor activities. Make changes to the schedule in advance and not at the last moment.
Limit distractions in the child's environment.
Make sure the child gets a healthy, varied diet, with plenty of fiber and basic nutrients.
Make sure the child gets enough sleep.
Praise and reward good behavior.
Provide clear and consistent rules for the child
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