Patent Abstract:
a simplified , quantitative electroencephalographic technique and apparatus for testing and assessing individuals for attention deficit hyperactivity disorder is described . the simplified procedure and apparatus is consistent with emerging neuroanatomical models of the etiology of adhd , makes the testing affordable to the public , and allows for practitioners to conduct the testing on an outpatient basis within their offices . the process comprises a new scanning method that obtains quantitative eeg data from an electrode placed at a single , active cranial site . multiple short periods of digitized eeg are obtained . the electrophysiological power in two frequency bands is examined . a computer that is programmed with the capacity to conduct a fast fourier transformation selects and statistically analyzes the power in these specific eeg frequency bands . a baseline neurometric index is obtained by calculating the ratio of the electrophysiological power recorded within the theta band by that recorded in the beta band while the individual maintains an eyes open , fixed gaze . thereafter , the individual being tested for adhd is evaluated under conditions requiring attentive behavior . a theta / beta power ratio is calculated for each of these tasks . finally , an average of the power ratios across the baseline , reading , listening and drawing tasks is calculated and an attentional index is obtained and compared to a database obtained through the evaluations of a normative sample of individuals not having adhd or any other neurological disorder . the assessment of the presence and severity of adhd is determined from this comparison .

Detailed Description:
generally speaking , the present inventive method for testing and assessing adhd is based upon earlier findings that indicated that the highest degree of differentiation between adhd patients and non - adhd controls was noted at the vertex [ 29 ]. therefore , the cz cranial site was selected for placement of the active electrode in performing the qeeg assessment . prior studies [ 24 , 30 ] had also indicated that differentiation between groups occurred when participants were involved in scholastic tasks ( e . g ., reading , listening , drawing ), as would have been expected . therefore , the difficulty sustaining attention during completion of these types of tasks ( as manifested on the qeeg testing ) provides a neurometric index for identifying the presence and degree of adhd . referring to fig1 the testing apparatus of this invention is illustrated . a vga monitor 14 is used to observe the testing being performed . the monitor 14 is connected to a personal computer 19 , having a minimum 486 operating system . the computer 19 is connected to a digital processing card 18 ( contained in an autogenics a - 620 instrument ) and an analog - to - digital converter 17 ( stoelting autogenics part no . 7000 - 08 ) that is connected to a single channel , dual frequency eeg 16 ( autogenics a - 620 eeg instrument ). the computer 19 is also connected to a computer storage site 20 containing the normative index data base . the basis of this invention involves obtaining qeeg recordings using the single channel eeg recording device 16 . the computer 19 is programmed to select and statistically analyze specific eeg frequency bands . the eeg 16 and the associated software for programming the computer 19 consist of an autogenics a - 620 electroencephalograph with associated assessment software provided by the stoelting - autogenics company located in wood dale , ill . the individual 15 is connected to the single channel eeg device 16 via a monopolar ( referential ) eeg cable with junction box ( autogenics part no . 800 - 032 m ), not shown . this system provides clinicians with a quantitative analysis of electrophysiological recordings in two frequency bands : theta ( 4 - 8 hz ) and beta ( 13 - 21 hz ). four short periods ( 90 seconds each ) of digitized eeg are obtained . a fast fourier transformation algorithm , commonly utilized in this field , is used to process the signals and transform them into the data required for evaluation of adhd . referring to fig2 a and 2b , a flow chart 100 depicts the sequential steps of the testing method for quantitatively diagnosing and evaluating adhd in individuals using the apparatus shown in fig1 . the individual being tested is prepared , step 101 , and the eeg electrode is attached to the scalp at cranial site cz , step 102 . thereafter , ear electrodes are attached to the individual &# 39 ; s ear lobes , step 103 . impedance and offset potentials are obtained , step 104 . particular eeg frequency bands are then selected for the adhd assessment , step 105 . the eeg signals are amplified and digitized , step 106 during a 90 second period , in which the individual maintains an eyes open fixed gaze . then a fourier analysis of the signals is obtained , step 107 . the signal is analyzed for muscular and ocular movement artifact , step 108 . the computer 19 ( fig1 ) then processes the data and calculates the electrophysiological power ( pw ) recorded at 4 - 8 hz and 13 - 21 hz , step 109 , as well as a ratio of power ( theta / beta ) at these frequencies , step 110 . the individual is then given a number of tasks requiring attention . from a first test , step 111 , an attention ratio ( theta / beta power ratio ) is obtained . additional attention tasks are given to the individual , step 111 , which require repetition of steps 105 through 110 , as shown by exit line 112 and flow chart connector b . thereafter , the overall neurometric index is computed , step 113 . the tested index obtained in step 113 is then compared to a normative database index that has been determined during investigations conducted by the inventors , step 114 . the following is a more detailed step - by - step description of a typical test procedure used in this invention . 1 . the vertex ( cz ) is located using the international 10 - 20 system of electrode placement . 2 . the area is cleaned using omni prep ( or equivalent ) and isopropyl alcohol . a small amount of conductive paste ( e . g ., ten 20 ) is applied to the scalp and a grass gold disc electrode with hole ( e5gh ) and the sensor are attached to the scalp . a similar cleaning procedure is used for preparing the ear lobes . one pair of gold disc electrodes in ear clip ( grass e34d ) is attached to each ear lobe . quality of preparation is assessed via an autogenics electrode tester . impedance reading is set below 10 kohms . offset potential is set below 10 mv before recordings are obtained . 3 . band frequencies are selected with 4 - 8 hz defined as theta and 13 - 21 hz defined as beta . once the sensors are tested and band frequencies defined , the individual &# 39 ; s electrophysiological activity at cz is recorded during the following 90 second tasks : a ) eyes fixed baseline : the patient is seated in front of the computer monitor display and instructed to focus his / her gaze on the monitor &# 39 ; s &# 34 ; on / off &# 34 ; indicator light . eeg recordings are obtained for 90 seconds . after the task is completed , the eeg record is reviewed in two second intervals (&# 34 ; epochs &# 34 ;) in order to manually filter out epochs containing excessive emg artifact ( e . g ., body movement , eye rolls or blinks ). a minimum of 15 low artifact epochs ( i . e ., no evidence of eye rolls / blinks and peak emg output below 15 mv ) is required for completion of this task . b ) silent reading : the next 90 second task is reading . material that is age or grade appropriate is selected from school reading texts , reading tasks from the kaufman test of educational achievement , the peabody individual achievement test , or other age - related reading tests , and the material is read silently by the patient . again , after completion of this task , the eeg is reviewed in two second intervals to eliminate epochs with excessive emg activity or eye movement / blink artifact . a minimum of 15 low artifact epochs is required for completion of this assessment task . c ) listening : a 90 second listening task occurs next . age appropriate material is selected and read by a clinician , as described for task ( b ), above . eeg review is conducted , as with tasks ( a ) and ( b ). d ) drawing : a stable drawing surface is placed in front of the individual . the person is instructed to copy geometric figures from one of the following tests : beery - bender gestalt , benton visual retention test , mccarthy scales of child development . electrophysiological activity is recorded for 90 seconds with review , as for the aforementioned tasks . after the data is collected , a statistical analysis is performed . the analysis is first conducted by task and a ratio of electrophysiological power produced and recorded at 4 - 8 hz is divided by the power recorded at 13 - 21 hz . a separate ratio is calculated for each task . finally , an average ratio for the four tasks is calculated and an attentional index is derived . it is this attentional index that is used for comparison with the normative database . the specifications of the equipment used in the development of the current invention were as follows : signal acquisition was obtained using the aforementioned a - 620 eeg device . input was single channel , dual frequency . gain was 50 , 000 . noise was less than 1 mv pp , referred to input . differential input impedance was 200 kohms . common mode rejection ratio was greater than 100 db . amplitude range was 1 - 100 mv , rms . eeg frequency bands that could be recorded with this equipment ranged from 1 . 0 hz to 32 hz . sampling rate was 128 . a / d resolution was 12 bits ( 0 . 05 mv ). emg was also recorded with the a - 620 eeg device ( band pass frequency was 100 - 300 hz , fixed ). computer requirements were a pc , the minimum requirement being a 486 machine . in order to assess the ability of this invention to meet the standards for a valid and reliable assessment process , a series of studies have been conducted by the inventors [ 30 ]. although in the initial study [ 24 ], the inventors established a database founded on a qeeg examination of 482 individuals , cross validation , construct validation and test - retest reliability studies were required . for these reasons , five additional studies were conducted [ 30 ]. in the first study , the inventors compared the qeeg derived attentional index of 96 individuals diagnosed with adhd and 33 &# 34 ; non - clinical &# 34 ; controls , none of whom had participated in the initial validation study . this study was intended as a cross - validation study with non - clinical controls . anova results indicated significant differences between the two groups ( adhd vs . control ), with cortical slowing noted in members of the adhd , inattentive and the adhd , combined groups . using the critical values for cortical slowing established in the normative study as the basis for classification as adhd or non - adhd , 93 % of the individual participants were accurately classified . next , the qeeg derived attentional index was examined in 155 participants . of these individuals , 129 were classified as adhd , using the selection criteria developed in the initial study [ 24 ]; 13 individuals were classified with depressive disorders and 13 were classified with an oppositional defiant disorder based on rating scales and dsm - iv criteria . none of these individuals had participated in the initial validation study . significant differences were again noted in the results of the qeeg data , with cortical slowing only noted in the adhd groups . classification as adhd or non - adhd was accurate for 94 % of the participants . it was considered significant that the results of this study demonstrated that common co - morbid conditions , such as depression and oppositional defiant disorders , are not characterized by cortical slowing on the eeg . it was also considered significant that the absence of cortical slowing in the qeeg &# 39 ; s of patients diagnosed with oppositional defiant disorders and depression is consistent with pet and spect findings . amen and carmichael [ 31 ], using spect , reported increased activity in the anterior medial aspects of the frontal lobes in patients diagnosed with oppositional defiant disorder . previously , hollander [ 32 ], machlin [ 33 ], mordahl [ 34 ] and swedo [ 35 ] reported a similar pattern of increased metabolic activity , bilaterally , in the anterior medial portions of the frontal lobes on pet and spect examinations of patients diagnosed with affective disorder . as in the inventors &# 39 ; qeeg studies , cortical slowing was not observed in pet or spect procedures examining patients diagnosed with an affective or oppositional disorder . in order to assess the &# 34 ; construct &# 34 ; validity of their qeeg process , the inventors next examined the degree of diagnostic agreement between classification based on the attentional index and that derived from a cpt ( the test of variables of attention ). in this study 155 individuals were examined ( the same participants as described above ). as reported previously , 129 of these participants were classifiable with adhd , the remainder as either depressed or with oppositional defiant disorder . agreement between classification determined by the cpt and the qeeg was noted in 88 % of the participants . the degree of agreement was significant ( p & lt ; 0 . 001 ). in the fourth study , 83 participants classifiable as adhd using the previously described selection criteria and 18 clinical controls ( 9 with depressive disorders , 9 with oppositional defiant disorder ) were evaluated with the qeeg screening procedure as well as the addes . consistency between the two measures was assessed . the rate of agreement was 83 % ( p & lt ; 0 . 001 ). overall , the results of the construct validation studies provided further support for the qeeg measure as a laboratory test for adhd . finally , the inventors reported a test - retest reliability study of 55 individuals who met research criteria for classification as either adhd , inattentive or combined types . these individuals were evaluated on two occasions . during each assessment session , the qeeg scanning procedure for adhd was conducted over four conditions ( eyes open baseline , reading , listening , drawing ). each condition was 90 seconds in duration . an attentional index was calculated as in previous studies and the consistency of this index over the two testing sessions ( conducted 30 days apart ) was calculated . the correlation coefficient ( r = 0 . 96 ) revealed a significant level of consistency ( p & lt ; 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( 1998 ). assessing adhd via quantitative electroencephalography : test validation and reliability studies . presented at ch . a . d . d .&# 39 ; s tenth annual conference , new york . paper in preparation . amen , d . g ., & amp ; carmichael , b . a . ( 1997 ). oppositional children similar to ocd on spect : implications for treatment . journal of neurotherapy , 2 , 1 - 7 . hollander , e . ( 1992 ). hyperfrontality and serotonin in ocd . presented at the annual meeting of the american psychiatric association . machlin , s . r ., harris , g . j ., peralson , g . d . ( 1991 ). elevated medial - frontal cerebral blood flow in obsessive - compulsive patients : a spect study . american journal of psychiatry , 148 , 1240 - 1242 . nordahl , t . e ., benkelfat , c ., & amp ; semple , w . e . ( 1989 ). cerebral glucose metabolic rates in obsessive compulsive disorder . neuropsychopharmacology , 2 , 23 - 38 . swedo , s . e ., schapiro , m . b ., & amp ; grady , c . l . ( 1989 ). cerebral glucose metabolism in childhood onset obsessive compulsive disorder . archives of general psychiatry , 46 , 518 - 523 . since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in this scientific field , the invention is not considered limited to the example chosen for purposes of disclosure and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention . having thus described the invention , what is desired to be protected by letters patent is presented in the subsequently appended claims .