exploring the evaluation of antiepileptic drug change in people with intellectual disabilities and...

Epilepsy&

Epilepsy & Behavior 5 (2004) 58–66

Behavior

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Exploring the evaluation of antiepileptic drug change in peoplewith intellectual disabilities and high-frequency epilepticseizures: seizure control and sustained responsiveness to

the environment

Clare Smith, Mike Kerr, David Felce,* Helen Baxter, Kathy Lowe, and Andrea Meek

Welsh Centre for Learning Disabilities Applied Research Unit, University of Wales College of Medicine, Cardiff, Wales, UK

Received 22 August 2003; revised 20 October 2003; accepted 21 October 2003

Abstract

Purpose. Optimum antiepilepsy medication should be successful in reducing seizures with minimal adverse effects on the patient�sability to concentrate or general level of awareness. The purpose was to investigate the potential of a method of measuring re-

sponsiveness to environmental events as a means of reflecting awareness levels among people with intellectual disabilities undergoing

review of medication for high-frequency epileptic seizures.

Methods. Observations of 22 participants referred to a specialist clinic were conducted three times a month over a 5-month period

following the initial baseline measures and clinical intervention. Behavioral responsiveness was measured by calculating the like-

lihood of appropriate activity occurring given the occurrence of staff interaction. This likelihood was represented by the statistic

Yule�s Q. Seizure frequency was also evaluated.

Results. Participant responsiveness after drug review was similar to baseline indicating an absence of long-term adverse effects.

Participants experienced a significant decrease in seizure frequency.

Conclusion. It was concluded that drug review led to seizure reduction while behavioral measurement confirmed no loss of

responsiveness.

� 2003 Elsevier Inc. All rights reserved.

Keywords: Intellectual disabilities; Medication; Outcome; Behavioral responsiveness

1. Introduction

There are a number of people within the general

population who experience difficulties in communica-

tion, such as very young children, people with Alzhei-mer�s disease, and people with intellectual disabilities.

Where such problems are acute, personal well-being and

state of mind are largely inferred from people�s ob-

servable behavior, with reliance on second-hand re-

porting from family or carers being common. Such

reliance can call into question the validity of the infor-

mation gathered on the efficacy of professional inter-

vention [1]. This problem has been particularly

* Corresponding author. Fax: +029-20610812.

E-mail address: [email protected] (D. Felce).

1525-5050/$ - see front matter � 2003 Elsevier Inc. All rights reserved.

doi:10.1016/j.yebeh.2003.10.018

highlighted where epilepsy and intellectual disabilities

occur together due to the high prevalence of the condi-

tion among people with intellectual disability and the

additional difficulties that this comorbidity causes.

The frequency of epilepsy occurring in people withintellectual disability is much higher than in the general

population and seems to increase with the severity of

disability [2–4]. Epidemiological studies suggest that as

many as one-fifth of the population of people with in-

tellectual disabilities have epilepsy [5–8] and reported

that people with such a ‘‘dual disability’’ showed poorer

life skills than their peers without epilepsy, and that

behavioral disturbances, such as aggression and self-in-jury, were particularly associated with frequent seizures

and with antiepileptic polytherapy. The coexistence of

epilepsy and intellectual disability also seems, as one

mail to: [email protected]

C. Smith et al. / Epilepsy & Behavior 5 (2004) 58–66 59

would expect, to be a factor associated with the impactof caring. Espie et al. [9] found that carers experience

strain and that family carers may be particularly prone

to experience clinically significant levels of anxiety and

depression.

Both conditions predispose to earlier mortality [10].

People with an intellectual disability are known to have

a lower life expectancy than the general population with

an estimated standardized mortality ratio (SMR) of 1.6[11]. The probability of survival decreases as the severity

of intellectual disability increases [12]. This higher risk

of mortality is increased for people with coexisting epi-

lepsy whose SMR may be as high as 5 [11,13,14]. With a

condition occurring with such frequency and with such

consequences for those concerned, it is possible to see

why investigation in this area is badly needed.

The introduction of new medication is a particularissue for professionals and families alike because of the

fear of undesirable side effects, such as suppression of

arousal [15]. In treating epilepsy, doctors strive to pre-

scribe the right type and level of medication to be suc-

cessful in reducing seizures but with minimal adverse

effects on other aspects of the patients� lives, such as

their level of awareness or ability to concentrate. How-

ever, achieving such a balance in managing epilepsy inpeople with intellectual disabilities is made more difficult

because of a number of problems.

It is common for there to be a higher than desirable

frequency and severity of seizures refractory to treat-

ment [16]. This may mean that patients have a greater

vulnerability to any cognitive side effects if dosages are

increased to maximize seizure control. The situation is

further complicated by the high prevalence of psychi-atric and behavioral disturbance in people with intel-

lectual disabilities [17]. A large proportion of people

with intellectual disabilities experience long-term expo-

sure to drug treatment for behavioral problems [18–21].

This may lead to involuntary body movements, such as

tardive dyskinesia, which can look like seizure activity

[22].

Moreover, the assessment of the efficacy of medica-tion can be hampered by confusion between general

behavioral abnormalities and behavior problems caused

by epilepsy or the antiepileptic medication itself [3,23].

Early observations found that approximately two-thirds

of people with severe intellectual disabilities living in

institutions displayed stereotypical behavior including

head movements, rocking, and jerking [24,25]. Differ-

entiating this behavior from the pattern of behaviortypically seen in complex partial seizures, particularly

when there are associated ictal or postictal automatisms,

is complex.

Current measures used to assess the effectiveness of

medication, such as seizure diaries and seizure severity

scales, make it comparatively easy to judge whether im-

provements have occurred in the number and level of

seizures a person has experienced. However, it is oftenless easy for carers to notice other, more subtle changes in

the person�s state of alertness and behavior. It is unlikely

that the commonly used primary outcome measure, sei-

zure reduction, adequately assesses such quality-of-life

outcomes. A way of measuring a patient�s responsivenessto environmental stimuli would complement existing

evaluation approaches and give practitioners a more ac-

curate overview of medication effects.Observational methods for studying human behavior

and the interactions people have with others have made

a substantial contribution to the evaluation of services

for people with severe intellectual disability [26,27]. The

extent to which people are engaged in activity has been

measured reliably. The measure has been shown to

discriminate between institutional and community ser-

vices [26], day services and work [28], and people withlower and higher assessed adaptive behavior [29]. Ob-

served activity has also been shown to correlate signifi-

cantly with scores on staff reported activity scales [30].

In addition, observational methods have been used to

evaluate the impact on resident activity of changes in the

way staff attend to residents brought about by staff

training [31,32].

The application of palmtop computers to behavioralmeasurement has permitted real-time multiple-category

observation to be undertaken in real-world settings [33].

Sequential analysis [34] allows behavior occurring in a

period of time to be analyzed in relation to the envi-

ronmental states that precede or follow it. A person�sresponse to a defined environmental stimulus can be

represented by the conditional probabilities of the re-

sponse occurring or not given the occurrence and non-occurrence of the stimulus in question [35]. Such

probabilities divided one by the other constitute an odds

ratio, a measure of the size of effect that the stimulus has

on the person�s behavior. For example, Felce et al. [36]

were interested in whether staff became more effective at

assisting residents to engage in activities after they had

been given training. The odds ratio of resident engage-

ment in activity given the receipt of assistance aftertraining was compared with that before training. A

significant increase was interpreted as showing that staff

had become more effective at assisting residents. In other

words, a changed quality of assistance had caused an

increased probability of the resident response, engage-

ment in activity.

This approach to evaluating the responsiveness of

people with intellectual disabilities may have applicationbeyond analyzing the impact of changed environmental

stimuli. Responsiveness to unchanged environmental

stimuli but under different types or levels of medication

may provide a methodology for assessing the behavioral

impact of drug treatment in this population. The pur-

pose of this study was to explore the application of this

approach to studying the behavioral consequences of

60 C. Smith et al. / Epilepsy & Behavior 5 (2004) 58–66

antiepileptic medication review among adults withintellectual disabilities and severe epilepsy.

The aims of the present study were (1) to assess the

impact of antiepileptic drug change in terms of not only

seizure control but also sustained responsiveness to en-

vironment stimuli, and (2) to explore the association

between change in seizure frequency and such respon-

siveness.

2. Method

2.1. Participants and settings

A specialist outpatient epilepsy unit at the University

of Wales College of Medicine served a population of

approximately 1.5 million people in South Wales andreceived referrals of adults with intellectual disability

and severe epilepsy. It was intended to recruit 20 par-

ticipants, a number determined by practical consider-

ations concerning volume of data collection and power

to demonstrate statistical significance. Participants were

recruited prospectively during a 12-month period using

the following inclusion criteria: (1) a change in antiepi-

leptic medication was clinically indicated, and (2) in-formed consent and/or assent were given. Twenty-two

adults met these criteria. Full data sets were collected for

19; 3 people withdrew from treatment review during the

course of the study.

Six of the 19 participants lived in supported housing

and 13 lived in their family home. Ten participants were

male and the mean age of the sample was 32 years

(range, 18–46 years). Mean score on the Liverpool Sei-zure Severity Scale [37] at baseline was 31 (range, 8–69).

According to the Disability Assessment Schedule [38] 12

participants could not walk independently, 9 were

nonverbal, and 11 were not able to feed, wash, and dress

themselves. Six had severe challenging behavior and 11

were severely incontinent.

Mean score on Part One of the Adaptive Behavior

Scale [39] at baseline was 92 (range, 29–242), and on theAberrant Behavior Checklist [40], 40 (range, 4–78).

Mean score on the Psychopathology Instrument for

Mentally Retarded Adults [41] at baseline was 9 (range,

2–17). This assessment has eight sections and a score of

4 or more on each suggests caseness in relation to the

diagnostic category in question. Overall, 8 participants

were assessed at threshold levels in relation to one or

more categories. In addition, 11 were assessed as havingthe triad of social impairments characteristic of autistic

spectrum disorder [42]. Lower Adaptive Behavior Scale

scores were significantly associated with the presence of

the triad of social impairments (r ¼ �0:61, P < 0:01).Otherwise, correlations between the behavioral assess-

ments or between them and psychiatric caseness were

not significant.

2.2. Research design

Recruitment for the study was staggered over 24

months and each participant was studied for 6 months

including an initial baseline assessment and five re-

peated assessments at monthly intervals after clinical

intervention began. Clinical consultants remained in

charge of the drug treatment for all the participants

throughout the study and they were free to change themedication at any time, including stopping the intro-

duction of a new drug or the changed level of a current

drug. During the course of the study three participants

had their current drugs reduced, one had them in-

creased, and 15 had new drugs introduced. Details of

the medication changes for each participant during the

5 months after clinical intervention began can be found

in Table 1.

2.3. Measurement

2.3.1. Participant characteristics

Information on each participant�s adaptive behavior,

social impairment, psychopathology, and challenging

behavior was collected using well-established reliable

and valid assessment scales. Such characteristics arecommonly employed to define intellectual disability re-

search populations and have been recommended as re-

quired subject descriptors in epilepsy research [23]. Data

were collected by interviewing family members or direct

care staff who knew the person well using the Disability

Assessment Schedule (DAS) [38], the Adaptive Behavior

Scale Part One (ABS) (Community and Residential

Version) [39], and the Aberrant Behavior Checklist [40].Presence of psychopathology was assessed using the

Psychopathology Instrument for Mentally Retarded

Adults [41]. Items from the DAS relating to participants�language and means of communication, the quality of

their social interaction, and the extents to which they

engaged in symbolic activities, stereotypic behavior, and

echolalia were used to assess whether participants had

the triad of social impairments characteristic of autisticspectrum disorder [42].

2.3.2. Seizure data

Data on seizure frequency and severity (using the

Liverpool Seizure Severity Scale) were obtained by ca-

rers completing structured seizure diaries from baseline

to 5 months after drug change.

2.3.3. Participant activity and receipt of attention from

carers

Responsiveness to the environment was conceptual-

ized as behavior given receipt of attention from carers.

The behavior of each participant and the attention he or

she received were therefore observed directly. Observa-

tions were conducted three times each month for 6

Table 1

Details of participant�s drug intervention and dosage during post intervention observations

Client Drug intervention Seizure types Month 1 Month 2 Month 3 Month 4 Month 5

01 Introduction of topiramate alongside

current medication: lamotrigine 575mg

Tonic–clonic, atonic,

complex partial

25mg twice

a day

25mg AMAM

50mg PMPM

50mg twice

a day

50mg twice

a day

50mg twice

a day

02 Reduction in tiagabine Tonic–clonic, atonic,

tonic

5mg twice

a day

5mg daily Discontinued Discontinued Discontinued

03 Introduction of lamotrigine alongside

current medication: primidone 125mg

Absence, tonic–clonic,

myoclonic

25mg every

other day

25mg twice daily 50mg twice daily 50mg twice daily 50mg twice

daily

04 Increase in lamotrigine Tonic, tonic–clonic,

unclassified

300mg AMAM

200mg PMPM

300mg AMAM

200mg PMPM

300mg AMAM

200mg PMPM

300mg AMAM

200mg PMPM

300mg AMAM

200mg PMPM



Tonic, tonic–clonic,

absence, unclassified

25mg twice

a day

25mg AMAM

50mg PMPM

75mg AMAM

75mg PMPM

75mg AMAM

75mg PMPM

75mg AMAM

100mg PMPM


current medication: clonazepam 2mg

Myoclonic jerks 25mg every

other day

50mg daily 75mg daily 75mg daily 75mg daily


current medication: vigabatrin 2 g,

carbamazepine 200mg

Tonic–clonic, myoclonic,

tonic, unclassified

25mg daily 75mg daily 100mg AMAM

25mg PMPM

100mg AMAM

75mg PMPM

100mg AMAM

100mg PMPM


current medication: carbamazepine

700mg, diazepam 20mg, pericyazine

20mg

Tonic–clonic, complex

partial, unclassified

25mg daily 75mg daily 100mg AMAM

25mg PMPM

100mg AMAM

75mg PMPM

100mg AMAM

100mg PMPM


current medication: sodium valproate

2 g and lamotrigine 300mg

Tonic–clonic, atonic,

unclassified

25mg PMPM 25mg AMAM

25mg PMPM

25mg AMAM

50mg PMPM

25mg AMAM

50mg PMPM

25mg AMAM

50mg PMPM

10 Introduction of lamotrigine Tonic, complex partial 25mg every

other day



current medication: sodium valproate

1400mg, gabapentin 2700mg, clobazam

10mg, diazepam 2mg

Tonic–clonic, tonic,

absence, secondary

generalized

25mg daily 25mg twice

a day

50mg daily 50mg twice

a day

50mg twice

a day



and phenobarbital 30mg


absence, complex

partial

25mg PMPM 25mg AMAM

50mg PMPM

50mg twice

a day

50mg twice

a day

50mg twice

a day

13 Reduction in gabapentin Tonic–clonic, tonic,

myoclonic jerks, atonic

800mg

400mg

800mg

400mg

400mg

800mg

400mg

400mg

400mg

400mg PMPM Discontinued


current medication: carbamazepine

1200mg, vigabatrin 2 g, clobazam 10mg


unclassified

25mg daily 25mg AMAM

50mg PMPM

50mg twice daily 50mg twice daily 50mg twice

daily

15 Reduction in phenytoin alongside current

medication: carbamazepine 400mg, 600mg:

primidone 3mg; phenytoin 300mg

Tonic–clonic 275mg daily 250mg daily 225mg daily 200mg daily 175mg daily


current medication: carbamazepine 200mg;

400mg; sodium valproate 2 g

Tonic–clonic 25mg every

other day


C.Smith

etal./Epilep

sy&

Behavio

r5(2004)58–66

61

Table

1(continued)

Client

Drugintervention

Seizure

types

Month

1Month

2Month

3Month

4Month

5

17

Introductionoflevetiracetam

alongside

currentmedication:sodium

valproate

1700mg,lamotrigine225mg

Tonic–clonic,

tonic,

atonic

250mgdaily

250mg

AM

AM

500mg

PM

PM

500mgtw

ice

aday

500mgtw

ice

aday

500mgtw

ice

aday

18

Introductionoflamotrigine

alongsidecurrentmedication:

phenytoin

200mg,sodium

valproate

500mg,chlorpromazine75mg

Tonic–clonic,absence

25mgevery

other

day

25mgdaily

50mgdaily

75mgdaily

100mgdaily

19

Introductionoftopiramate

alongside

currentmedication:sodium

valproate

2g,

lamotrigine250mg,Diazepam

5mg

Generalizedtonic–clonic

25mgevery

other

day

50mgdaily

100mgdaily

100mgdaily

100mgdaily


months, including an initial baseline assessment and 5monthly assessments following clinical intervention.

Observations took place within the participant�s servicesettings (residence or day placement). Each observation

session lasted 2 hours. The location and time of day of

each observation session were held constant for each

participant but varied across them. The observations

themselves were conducted using Psion palmtop com-

puters programmed for real-time, multiple-category,data capture [43]. It was thus possible to produce a

complete record of participant behavior and the carer

attention each received during the observed period. One

key was designated for each observational code. In

general, keys acted independently allowing for concur-

rency of behavior. One key depression signaled the onset

of a code and a second depression signaled its termi-

nation. The data were stored within the computer in anarray that gave the time (in seconds) of the onset and the

termination of each behavior. Data were transferred to

an IBM-compatible personal computer for analysis.

Four carer and five participant behaviors were

measured.

Carer attention:

(i) Verbal instruction: spoken or signed instruction to

perform an activity.(ii) Prompting/demonstration: gestural or physical

prompting to perform an activity.

(iii) Physical guidance: direct physical help to do an

activity.

(iv) Conversation: spoken or signed interactions nei-

ther encouraging nor discouraging of activity (e.g.,

pleasantries).

Participant behaviors:(i) Social engagement: spoken, signed, gestured, or

other attempts to gain or retain the attention of another

person (except by challenging behavior) or the giving of

attention, as evidenced by eye contact or orientation of

the head, to another person who is reciprocally inter-

acting.

(ii) Domestic engagement: getting ready for, doing, or

clearing away a household or gardening activity.(iii) Personal engagement: getting ready for, doing, or

clearing away a self-help or personal activity.

(iv) Other engagement: getting ready for, doing, or

clearing away a recreational activity or educational ac-

tivity.

(v) Other: all other behavior including no activity,

unpurposeful activity, and challenging behavior (self-

injury, aggression to others, damage to property, ste-reotypy, and all other inappropriate behavior).

2.4. Analysis

The three observation sessions per participant each

month were arranged as a single file set. The following

operations were performed on each of the six file sets


(baseline and months 1-5 post medication review) foreach participant using a program for sequential analysis

called Harclag [43]:

1. the category total participant engagement in activity

was created by combining all occurrences of social,

domestic, personal and other engagement and its extent

calculated

2. the category receipt of carer attention was created

by combining all occurrences of verbal instruction,prompting or demonstration, physical guidance and

other conversation, and its extent calculated

3. the conditional probability of total participant

engagement in activity occurring within a 5-second lag

after receipt of carer attention was calculated.

The quantities in 1-3 above were then used to con-

struct a 2� 2 contingency table for the occurrence or

otherwise of total participant engagement in activitygiven the receipt or otherwise of carer attention (see

Fig. 1), as a prelude to the calculation of odds ratios and

Yule�s Q.

The application of odds ratios to the analysis of re-

lationships between events in observational data has

been described by Bakeman [44]. For a generic 2� 2

contingency table as illustrated in Fig. 1 with first row

quantities a and b and second row quantities c and d, theodds ratio for the variable defining the first column

occurring given the variable defining the first row oc-

curring is given by a=b divided by c=d which equals

ad=bc. This may be investigated as a concurrent asso-

ciation (lag zero) or lagged in time.

Odds ratios vary from 0 (perfect negative relation-

ship) through 1 (no relationship) to infinity (perfect

positive relationship). Yule�s Q is an arithmetic trans-formation [ðad � bcÞ=ðad þ bcÞ] which preserves the

rank ordering of the data and establishes a more con-

ventional range to the index so that 1 depicts a perfect

negative relationship, 0 no relationship, and +1 a perfect

positive relationship [45].

Yule�s Q was not calculable where there was no

participant engagement in activity or interaction from a

carer. Differences between baseline and postbaselinewere tested for significance using a Wilcoxon matched

pairs signed-ranks test [46].

Fig. 1. Two-by-two contingency table for total participant engagement

in activity given receipt of carer attention.

2.5. Reliability

Interobserver agreement was assessed by two re-

searchers observing 42 sessions simultaneously.

Agreement was defined by observers having the same

times for the onset and offset of codes within a tol-

erance of 4 seconds. Level of agreement was calcu-

lated for each code by using Cohen�s j modified to

allow for the setting of the tolerance [47]. This pro-vides an estimate of agreement corrected for chance

agreement. Summary j values were calculated as an

average weighted for the occurrence of the behavioral

category in question. j values for verbal instruction,

prompting/demonstration, physical guidance, and

other conversation were 0.78, 0.71, 0.85, and 0.70,

respectively. j values for participant engagement in

personal engagement, other engagement, and socialengagement were 0.87, 0.83, and 0.83, respectively.

There were insufficient amounts of domestic activity to

calculate a j score. Suen and Ary [48] suggest that a jvalue of 0.6 or higher is acceptable for observational

research. The above figures suggest that the occur-

rence of verbal instruction, prompting, physical

guidance, and other conversation from carers could

be reliably distinguished, as could participantengagement in personal, other nonsocial, and social

activity.

3. Results

At baseline, Yule�s Q for engagement occurring gi-

ven carer interaction was positive for 18 of the 19participants, indicating that carer attention made par-

ticipant engagement in activity more likely (baseline

mean, 0.77; range, )0.20–0.99). Five months following

drug intervention Yule�s Q had increased for 10 of the

19 participants, stayed the same for 2, and decreased

for 6. Yule�s Q was not calculable for 1 person.

Overall, change in Yule�s Q 5 months after antiepi-

lepetic drug change was not significant. However, therewas a significant increase in Yule�s Q for participants

with a baseline Yule�s Q below the baseline mean

(z ¼ �1:997, P < 0:05).The mean number of seizures experienced per month

at baseline was 75 (range, 2–577). Sixty-eight percent of

participants had in excess of an average of 2 seizures a

week. Five months postintervention, 16 people experi-

enced a decreased seizure frequency. The postinterven-tion mean (59; range, 0–499) was significantly lower

(z ¼ �2:68, P < 0:01).Across the entire sample, there was no significant

association between increases in Yule�s Q and decreases

in seizure number. However, there was a significant as-

sociation between these quantities for people with

challenging behavior and for people with threshold


levels of mental illness (r ¼ �0:808, P < 0:005, andr ¼ �0:708, P < 0:05, respectively).

Across the 6 months of study, change in Yule�s Q

and seizure frequency for each participant showed one

of three patterns (see Fig. 2). At baseline, subgroup 1

had marked seizure frequencies associated with low

behavioral responsiveness (i.e., low Yule�s Q). Behav-

ioral responsiveness increased through Months 2–5

accompanied by decreased seizure frequency. Bothreturned to baseline levels in Month 6. Overall, this

illustrates a short-term beneficial effect from antiepi-

leptic drug change. Subgroup 2 showed stability over

time. They had initially low seizure frequency associ-

ated with high responsiveness. Both were unaltered by

drug change. Subgroup 3 had an initial level of be-

havioral responsiveness inbetween those of the other

two groups associated with an intermediate seizurefrequency. Yule�s Q fell immediately after drug change

but returned to baseline by Month 6. Seizure fre-

quency fell progressively to low levels. Overall, this

illustrates a beneficial long-term effect of antiepileptic

drug change emerging after a short-term lowering of

responsiveness.

Fig. 2. Change in mean Yule�s Q and seizure frequency for three

groups: (1) participants 4, 10, 12, 14, and 20 whose Yule�s Q was

raised in Months 2–5; (2) participants 7, 9, 13, 15, and 17 whose

Yule�s Q stayed fairly constant throughout Months 2–6; and (3)

participants 2, 5, 6, 11, 16, and 22 whose Yule�s Q decreased in

Months 2–5.

4. Discussion

The aim of this study was to explore whether the

response of adults with severe learning disabilities and

high-frequency epileptic seizures to receipt of attention

from carers could be used as a sensitive means of rep-

resenting their responsiveness to the environment when

change in antiepileptic medication was undertaken to

review the effectiveness of seizure control. Sequentialanalysis was used to calculate the likelihood of partici-

pant engagement in activity following receipt of carer

attention, using a variant of the odds ratio, Yule�s Q.

The analyses showed a number of interpretable findings

that chime with clinical experience.

First, participant responsiveness after drug review

overall was similar to baseline, while the decrease in the

number of seizures participants experienced was signif-icant. This suggests that successful seizure reduction

following drug review was achieved with no loss of re-

sponsiveness. It is important to emphasize here that

treatment effectiveness need not result in an increase in

responsiveness among people whose responsiveness

is already high. The value of the behavioral analysis is

in providing a means of monitoring that there is not

an undue deterioration in functioning when medicationis changed.

Second, there was no association overall between

measures of responsiveness and seizure frequency but an

association was found for certain individuals. For peo-

ple regarded as having threshold levels of mental illness

and challenging behavior, reduced seizure frequency was

associated with increased responsiveness. Given that

these may be additional indicators of neurological ab-normalities, this finding is worth further investigation.

Third, the three patterns of change in responsiveness

and seizure frequency demonstrated reflect clinical ex-

perience. Responsiveness appeared lowered among

people with very frequent seizures refractory to treat-

ment. Drug change brought temporary beneficial change

to both quantities. However, improvements had disap-

peared by the sixth month. Responsiveness was at ceil-ing levels among people with infrequent seizures.

Change in medication did not affect either quantity.

Responsiveness was at a slightly lower level for people

experiencing an intermediate level of seizures. Increasing

control over seizures following medication change ap-

peared to be associated with a short-term deterioration

in responsiveness.

This methodology may be useful in the future in re-search studies aimed at differentiating effectiveness and/

or side effects of drugs or other therapeutic interventions

in people with severe communication problems. It,

however, has a number of limitations currently for

routine clinical practice: the volume of direct behavioral

observation is considerable and its analysis is time

consuming despite the availability of custom-made


computer programs. The lag analyses performed hererequire a certain minimal level of carer interactions from

which the conditional probability of participant re-

sponse can be calculated. Rather than relying on the

vagueries of natural environment assessment, it may be

possible to achieve this with a much lower level of ob-

servation by structuring a clinical assessment in such a

way as to ensure that the required carer interactions

occur. A more definitive demonstration of the method-ology utility would be required for such a development

to be worthwhile.

In conclusion, this study sought to demonstrate how

a behavioral measure can be employed to investigate

maintenance of behavioral functioning after antiepilep-

tic drug change in patients with intellectual disabilities.

In the past, measures such as seizure diaries and seizure

severity scales have made it comparatively easy to judgewhether improvements have occurred in the number and

level of seizures a person is experiencing. However, as-

sessing well-being and state of mind in this population

has typically been a problem. This study has shown that

a measure of behavioral responsiveness may be a useful

aid to interpretation when antiepileptic drug change is

undertaken in this population. Moreover, this investi-

gation has the validity associated with being conductedwithin normal clinical practice. What may work in this

context may prove more powerful in more tightly con-

trolled situations.

Acknowledgment

This study was funded by Wellcome Trust ProjectGrant #M/98/366.

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