        
                              CH.A.D.D. FACT SHEET
                           ATTENTION DEFICIT DISORDER 
                                      AND 
                    GENERALIZED RESISTANCE TO THYROID HORMONE
                                     (GRTH)
        
        Summary:
        
             Scientists at the National Institutes for Health (NIH) have
        discovered a link between Generalized Resistance to Thyroid
        Hormone (GRTH), a rare genetic disorder in which the body is
        unable to appropriately use thyroid hormone, and Attention
        Deficit Disorders (ADD).  GRTH is believed to be relatively
        uncommon; it is highly unlikely that a substantial percentage of
        people with ADD have GRTH.  The importance of this study is that 
        it provides further evidence that ADD is a neurobiological
        disorder.
        
        Discussion:
        
        NIH researchers have documented a link between ADD and GRTH, a
        disorder caused by a gene coding for a defective thyroid hormone
        receptor in a selected group of patients.  Persons with GRTH are
        unable to appropriately use thyroid hormone.  Thyroid hormone is
        one of the most important hormones in the body, as it controls
        the rate of metabolism.  It is essential for normal brain
        development.  The interplay between the thyroid hormone and
        thyroid receptor may influence neurotransmitter systems thought
        to be involved in the "organic operation" of ADD.  While
        scientists do not know the incidence of GRTH in the population,
        it is believed to be very rare.
        
        Researchers at NIH studied 104 members of 18 families. 
        Forty-nine person in the sample had GRTH; 55 did not.  Of the
        adults who had GRTH, 50% had ADD as a child.  Only 7% of the
        adults who did not have GRTH had ADD as a child.  Of the
        children who had GRTH, 70% were diagnosed as having ADD.  Of the
        children who did not have GRTH, 20% were diagnosed as having
        ADD.  The findings were published in The New England Journal of
        Medicine on April 8, 1993.  
        
        For the vast majority of children and adults with ADD, the study
        will have little immediate impact.  It is highly unlikely that a
        substantial percentage of person with ADD also have GRTH. 
        CH.A.D.D. does not recommend, nor does the study conclude, that
        children with ADD be screened for GRTH as a routine measure.
        
        This study represents an invaluable addition to our knowledge of
        ADD.  Evidence that, in a small group of person, ADD is
        associated with a specific gene defect lends credence to the
        growing understanding that AD is a neurobiologically based
        disorder.  When discussing the importance of this research,
        study co-author Dr. Alan Zametkin of NIH says, "It's not bad
        parenting, overcrowded schools, or unmotivated kids.  ADHD is a
        neuropsychiatric problem based on brain physiology."
        
        A document link between GRTH and ADD in some cases may prove to
        be a crucial clue as scientist s search for exact cause or
        causes of ADD.  The authors recommend other studies examining a
        possible link between ADD and other, less obvious
        thyroid-related causes of ADD.
        
        Questions and Answers:
        
        Q.   What does this study mean for parents of children with ADD?
        
        A.   It is one more piece of evidence that ADD is a
        neurobiological disorder.  Previous NIH research used advanced
        brain imaging techniques to document that adults with ADD have
        less than normal brain metabolism rates.  This body of research,
        combined with other data including family studies and drug
        response studies, should help lay to rest non-scientific
        "theories" that ADD is caused by such variables as a chaotic
        home environment, excessive television viewing, or poor diet.
        
        In the immediate future, this study will not affect the
        treatment and management of the vast majority of children with
        ADD.
        
        Q.   What is GRTH?
        
        A.   GRTH is a disorder caused by a gene coding for a defective
        thyroid hormone receptor.  According to Black's Medical
        Dictionary, thyroid hormone "is one of the most important in the
        body and controls the rat of metabolism."
        
        Thyroid hormone affects how strong our heart beats, how we
        concentrate and think, and the rate at which we burn calories. 
        Thyroid hormone s produced in a small gland, called the thyroid,
        located under the Adam's apple in the neck.  Once produced,
        thyroid is transmitted throughout the body via the blood stream.
        
        In order for thyroid hormone to exert its effect, it interacts
        with a specific receptor or "sensor' located in the nucleus of
        cells in the body.  When there is too little thyroid hormone in
        the body, a person may complain of tiredness, feeling cold all
        the time, depression, an increase in weight or an inability to
        loose weight, and leg cramps.  Children with too little thyroid
        hormone in the body may also experience abnormally slow growth. 
        When there is too much thyroid in the body, the person may
        complain of heart palpitations, feeling hot all the time, weight
        loss despite and increase in appetite, nervousness, hair loss,
        and trembling hands.  In some people, there is plenty of thyroid
        hormone, but due to a genetic defect the thyroid receptor is
        prevented from binding with the thyroid hormone.  This leads t a
        situation in which the person has high levels of thyroid hormone
        in the blood, but has symptoms similar to someone with too
        little thyroid hormone.  Such a condition, first identified in
        1972, is called generalized resistance to thyroid hormone or
        GRTH.
        
        GRTH can be treated.
        
        Q.   How many people have GRTH?
        
        A.   The exact incidence of GRTH is not known.  However, we do
        know that GRTH is a very rare genetic disorder whereas ADD occurs
        in 
        about 3-5% ofthe population.  This means that if a person has
        GRTH, 
        it is likely that he or she will also have ADD symptoms.  But the
        reverse is not true.  If a person has ADD, it is not likely that
        he or she will also have GRTH.  To better determine the
        incidence of GRTH, NIH researchers are collaborating with the
        Newborn Screening Program of the Wadsworth Center for
        Laboratories and Research of the New York Sate Department of
        Health to identify infants with GRTH.
        
        Q.   Should children with ADD be routinely tested for GRTH?
        
        A.   CH.A.D.D. considers this an important study, adding much to
        our knowledge about ADD.  However, given that GRTH is such a
        rare disorder, CH.A.D.D. believes that it wold be premature to
        conclude that because of this study all children with ADD should
        be test for GRTH.  You may want to consult with your psysician
        as to whether to have your child (or yourself if you are an
        adult with ADD) tested for GRTH.  Conversely, if your child has
        GRTH, you may want to have him or her assessed for the presence
        of ADD symptoms as well s specific learning disabilities.
        
        Q.   Will treatment for GRTH result in improvement in the
        symptoms
        of ADD?
        
        A.   It is not yet known whether treatment for GRTH will also
        result in improvement in the symptoms of ADD.  Please consult
        with your physician should you have further questions about
        the connection between GRTH and ADD.
        
        This fact sheet is based upon the article entitled, "Attention
        Deficit-Hyperactivity Disorder in People with Generalized
        Resistance to Thyroid Hormone" published in the April 8, 1993
        issue of The New England Journal of Medicine by Peter Hauser,
        M.D., et al.
