Neuropsychological functioning in children of patients with schizophrenia

 

1. Dr. S. Anuradha M.A., Ph.D, Psychologist*,
Schizophrenia Research Foundation, Chennai.
2. Dr. Latha Srinivasan, Ph.D. Psychologist
Hunter New England Area Health Service,
391-393, Main Road, Cardiff, NSW 2308, Australia.
3. Dr. R. Padmavati, MD, DPM Psychiatrist
Schizophrenia Research Foundation, Chennai

 

 

Summary :

Introduction: Neurobehavioral deficits in children have been hypothesized as indicators of development of schizophrenia in children at genetic risk. A wide array of neuropsychological and behavioral problems has been identified as vulnerability markers. Literature on children at risk from India is limited.

Aims: This study aimed at identifying children within a risk group, who are at high risk of developing schizophrenia.

Methods: The study subjects comprised of children whose one or both parent was diagnosed as schizophrenia. Neuropsychological assessments, using standardized tests were used to assess cognitive functioning in the children. The tools included the Weschler’s Memory scale, the Trail Making tests, the Category Fluency test and the Pin Test. Information on behavioral problems was obtained from a detailed interview with parents and on observation at clinical settings. The subjects were compared to controls, matched to subjects on age, gender and socio-economic status.

Results: Children at risk of developing schizophrenia showed significant attentional, visuomotor and memory deficits when compared to the children from the control group. The children at risk also showed a greater frequency of behavioral problems when compared to controls.

Conclusions: This study reconfirms presence of neurocognitive and behavioral deficits occurring more frequently in children at risk of developing schizophrenia than in children born to parents who do not suffer from schizophrenia. This delineation of children at a high risk of developing the illness would enable planning regular follow up and implementation of specific intervention strategies to prevent progression to psychosis.

Introduction :

Neurobehavioral deficits in children of persons with schizophrenia have been viewed as indicators of development of schizophrenia in subjects at genetic risk. Identification of areas of dysfunction, which are manifested in the individual’s interpersonal behavior and functioning, is critical to secondary prevention of the illness. Although risk is increased for the biological offspring of parents with schizophrenia, most children never develop schizophrenia. This underscores the need to identify those individuals within “at risk” groups, who are at highest risk for disorder.

A wide array of neurocognitive deficits has been identified as vulnerability markers. Several studies have demonstrated that poor attention skills in preteens to early teenage years highly correlated with the development of schizophrenia spectrum disorders in early adulthood (Erlenmeyer-Kimling et al, 1978; Rutchman et al, 1986; Mirsky et al, 1988; Mirsky et al, 1991). Children at risk showed poor visual motor coordination and were more distractible in the performance of an attention-cancellation task than the controls (Neuchterlain et al, 1983; Lifshitz, 1995). Deficits in attention, motor speed and information processing were noted in studies assessing neurobehavioral deficits (Cornblatt et al, 1985; Marcus et al, 1993). Short term verbal memory was impaired in 83% of offsprings who later developed schizophrenia (Mirsky et al, 1995).

Disturbances in social behavior such as impairment in interpersonal functioning, social withdrawal and aggressive behavior have been reported in several studies (Watt et al, 1982; Auerbach, 1993; Hans, 2000). Children at risk for schizophrenia, were also noted to behave differently at school as compared to other children, in that they presented greater disharmony, less scholastic motivation and more emotional instability than comparison subjects (Watt et al, 1982; Dworkin et al, 1994; Hans, 2000)

Literature on children at risk is sparse in India. In a study of school age offsprings, it was found that children at risk had poorer attention span, longer auditory and visual reaction times than controls (Shah et al, 2003). The same study also reported social problems in children such as getting teased, acting young, and not getting along with other kids, being clumsy and overweight.

Materials and Aims :

The current study was undertaken with an aim to identify individuals within a risk group, who were at high risk of developing schizophrenia. The study compared neuropsychological functioning in children at risk with normal children born to normal parents. Information was also elicited on behavioral problems in the two groups, to ascertain if the group at risk had a higher occurrence of such problems. Children at risk were defined as “those at genetic risk for schizophrenia by virtue of having one or more parents with schizophrenia”. The Institutional Review Board of the organisation approved this study.

Sample: A total of 100 children, whose one or both parent, had a diagnosis of schizophrenia according to DSM IV were recruited as cases, or children at risk. These children were identified from in-patients and outpatients, taking treatment at the Schizophrenia Research Foundation a non-governmental organisation, which offers treatment and rehabilitation for persons suffering from schizophrenia

The control group comprised of hundred children of parents who had no history of schizophrenia or other psychiatric problems. The children did not have any historical evidence to suggest a diagnosable psychiatric illness. Also, there were no psychiatric problems in any first degree relative. The controls, identified from the neighborhood of the children at risk, or from the same class at school, were matched with the children at risk group for age gender and socioeconomic status.

In both the groups, the children who had completed basic primary level education in order to perform the neuropsychological tests were included. Children with a diagnosis of DSM IV mental disorders, mental retardation, epilepsy, head injury with loss of consciousness, substance abuse and other disorders that might cause neuro- psychological impairment were excluded. The process of testing was explained to all the children, in the presence of the parents. Informed consent was obtained from the parents, before the children participated in the study.

Instruments :

The following neuropsychological tests, which have been standardized for the Indian population, were used to assess various cognitive dysfunctions in the subjects
1. Weschler Memory Scale - WMS (Weschler, 1987): This is a test of verbal and nonverbal memory. This scale consists of separate subscales including mental control, logical memory, visual memory and paired associate learning. The dependent measure is an overall memory quotient.
2. Category fluency test (Lezak, 1983): This is a test of verbal fluency. It involves verbal recall of items that fall in a particular category within a time limit of 1 minute. The total number of responses given by the subject would be the dependent measure
3. Pin test (Satz and Elia, 1989): This test measures fine motor control, speed and dexterity. The subjects are required to punch as many holes on a paper for 30 seconds. Subjects do this task twice with each hand. The average number of holes punched by each hand would be the dependent measure.
4. Trial making test A (TMT-A) and Trial making test B (TMT-B) (Reitan, 1955): These tests are part of the Halstead-Reitan battery, used as measure of visual searching, visual sequencing, perceptuo-motor speed, and the ability to make alternating conceptual shifts efficiently. This test assesses psychomotor speed and mental flexibility.

Methods:

All children underwent neuropsychological assessment, administered by a single rater (SA). The entire battery took about one and half to two hours. In both groups, qualitative information on the child’s behavior was obtained from the parents. Behavior during the interview was observed and documented. The data obtained was analysed using the SPSS version 10.

Results:

A total of 200 subjects, 100 each in cases and controls were assessed. There were 52 boys and 46 girls amongst cases and 48 boys and 54 girls in the control group. The mean ages of the groups were 15.41 (s.d.5.27) in the study group, and 14.72 (s.d.1.88) in the controls. The age range was 10-18 years. Majority of the children were in the higher secondary school. There were no statistical differences between the cases and controls
on gender, age and socioeconomic status

Most of the tests on neurocognitive functioning showed that children at risk performed poorly when compared to the controls. Table 1 shows the findings on the different subscales of the Weschler’s Memory Scale. The mean scores for children at risk in each subscale were lower than the control group. Using the Student’s t-test, the differences in the mean scores were statistically significant. Similar findings were seen for the Trail Making tests and Category Fluency test. No differences were seen for the mean scores of the Pin test. (Table 2).

Qualitative information and observations on behavior revealed that children at risk showed poorer social adjustment, more problems in peer relationships, greater frequency of adamant behaviors and aggression than in the control group. Problems reported at home included poor personal care, faulty eating habits, and excess hours of television viewing, refusal to comply with parental requests/demands, disobedience and hostility against members of the family or excess use of mobile phones. At school, there were consistent complaints of inadequate performance, poor attention and difficult behaviors like failure/ refusal to adhere school rules, aggressiveness with classmates or distracting other students in class. Some children were noted to be shy, clumsy, and prone to be teased by other children.

Children in the study group showed occurrence of antisocial behaviors. Some of the behaviors noted were thieving, business relationships with persons involved in illegal businesses such as dealing stolen goods, acting as messengers for drug users, involving in gang wars. These behaviors were not reported in any of the children in the control group.

Discussion:

The findings of the present study indicate the presence of neurocognitive dysfunctions in children at risk to develop schizophrenia. It also throws light on the behavioral problems observed in the study group.

The battery of neurocognitive tests used in the present study has shown that the children of schizophrenia patients scored poorer in attention, concentration, memory, problem solving skills and perceptual motor skills. This has been amply supported in a number of studies of populations at genetic risk for schizophrenia (Nagler et al, 1985; Mirsky et al, 1986; Mirsky et al, 1992). Impairment in these essential cognitive functions is seen not only as a core factor in the etiology of the disorder (Marcus, 1985; Erlenmeyer-Kimling, 1993) but also as a significant predictor of who will actually develop a schizophrenia spectrum illness.

Attentional skills as demonstrated by WMS digits forward and backward tests and TMT A & B, were poorer in the study group as compared to normal. Several studies have shown poor attention skills in preteens to early teenage years and this finding has also correlated highly with the development of schizophrenia spectrum disorders in early adulthood (Erlenmeyer-Kimling et al 1978; Rutchman et al, 1986; Mirsky et al, 1988; Mirsky et al, 1991; Erlenmeyer-Kimling, 1993; Shah et al, 2003). These studies suggested that impaired attention in high risk children might represent a biobehavioral marker for the disorder. Analyses with adult outcome measures in the Jerusalem Infant Development Study suggested that attentional dysfunction measured in childhood by Digit span subtest may be associated with later non – paranoid psychoses (Marcus, 1985). Early injury to the brain stem integrating systems that regulate motor, sensory and arousal functions may contribute to the attentional disturbances seen in children at risk (Erlenmeyer-Kimling, 1993).

The present study did not show any statistical difference in speed and motor dexterity, as assessed by the Pin Test, between the two groups. It is likely that this test may not have been sensitive to identify difference in motor dexterity between the children at risk and those not at risk. Significantly poorer visual motor coordination deficits as identified by the TMT-B, in subjects as compared to the children in the control group found in the present study replicates the findings of other studies (Silverton, 1988; Mirsky, 1995). Previous studies hypothesized that these deficits could represent the squeal of early injury to the brain stem integrating systems that regulate motor, sensory and arousal functions. They also suggested that this might represent a biobehavioral marker for the disorder.

Although this study did not adopt standardized scales for assessing behavioral problems, qualitative information on behavioral problems noted poorer social adjustment, more problems in peer relationships, greater frequency of adamant behaviors and aggression than in the control group. This was keeping with a similar study (Auerbach et al, 1993) which noted that the strongest discrimination of the children of schizophrenia patients from the comparison groups lay in social withdrawal, and the effect was strongest in the males. Our study however did not show any gender differences in aggressive or withdrawn behavior in the children in the study group.

Our study showed that antisocial behaviors were reported in children from the study group. Some of the behaviors like, thieving, involving in relationships with people in illegal businesses such as selling stolen cell phones, lap tops and other such valuables, selling drugs, involving in “gang wars”, could be explained by a failure to develop healthy interpersonal relationships. It was noted that the children in the study group had more social problems in terms of not getting along with other kids, often getting teased by other children and being clumsy. The findings replicate those reported in other studies (Dworkin et al 1994; Hans et al, 2000; Shah et al, 2003) These studies have reported that adolescents at risk for schizophrenia showed problems in social adjustment especially in the area of quality of relations with other young people and failure to relate in age typical ways. Data from several studies support the view that social impairments and behavior problems may be vulnerability markers.

Conclusion: Using standardized neurocognitive assessments, this study has been able to identify significant attentional, visuomotor and memory deficits in children with parents having schizophrenia as compared to children of mentally healthy parents. Although standardised methods of eliciting information on behavioral problems were not adopted, this study provides insights into the nature of behavioral problems that are exhibited by children at high risk. These findings may be clinically relevant for the identification of children within a risk group, who may be at a higher risk of developing schizophrenia. The findings also imply the need to plan specific intervention strategies to prevent progression to psychosis. Future studies need to focus on sensitive neurocognitive testing methods and standardized behavior checklists to help identification of children with a greater chance of developing Schizophrenia.

Table I : WESCHLER’S MEMORY SCALE

 

	Study	Control	t- value	Significance
Personal and current information	4.24 (+ 1.2)	5.18 (+.9)	6.154	.000
Orientation	4.45 (+.7)	4.90 (+.3)	5.522	.000
Mental Control	7.74 (+1.5)	8.25 (+1.5)	2.392	.018
Logical Memory	9.78 (+2.9)	12.69 (+3.3)	6.500	.000
Digit Forward	6.26 (+1.1)	7.01 (+.9)	5.075	.000
Digit Backward	4.59 (+1.1)	5.53 (+1.1)	5.974	.000
Visual Reproduction	9.92 (+2.5)	11.41(+1.7)	4.829	.001
Associate Learning	15.27 (+3.6)	18.06 (+3.0)	5.852	.000

 

Table II: Comparison of performance on Pin Test, Trail Making, and Category Fluency test

Scale	Sample	Normal	T-value	Significant
Pin Test (Right hand)	40.61 + 9.42	39.66 ± 7.51	0.793	NS
Pin Test (Left hand)	32.10 ± 7.48	31.51 ± 7.01	0.576	NS
Trail Making A	54.32 ± 24.06	40.38 ± 17.89	-4.650	.000
Trail Making B	120.87 ± 46.06	91.28 ± 41.81	-4.756	.000
Category Fluency (Number of items)	10.86 ± 3.45	14.35 ± 4.30	6.314	.000
Category Fluency Categorisation	7.01 ± 2.43	8.87 ± 2.12	5.747	.000

Acknowledgements :
This study was undertaken with help of a grant from the Sir Dorabjee Tata Trust Mumbai, India. We thank all the subjects who were recruited into the study, especially the children who comprised normal controls.

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* Address for Correspondence:
Dr S.Anuradha
Schizophrenia Research Foundation
R/7 A North Main Road
Anna Nagar West
Chennai - 600 101

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