Population studied

During the period March 1991 to December 1997, 506 children and adults with autistic spectrum disorders were referred to the Elliot House Centre for Social and Communication Disorders, which is the National Autistic Society's tertiary referral centre and accepts referrals from anywhere in the UK or overseas. The majority (94%) of these were seen at Elliot House for diagnostic assessment. The remainder were seen where they were currently living: in residential homes, hospitals or, in a few cases, their parents' homes.

The Elliot House team tends to see children and adults presenting complicated diagnostic problems. The fact that the staff members have a particular interest in catatonia has also become known and probably influences the pattern of referrals.

Criteria for catatonia

There are no generally accepted standardised criteria for diagnosing catatonia. In this study, a diagnosis of catatonia was given when exacerbation of certain features of behaviour occurred in sufficient degree to interfere with movement and everyday functions of self-care, education, occupation and leisure. The essential features were:

1. (a) increased slowness affecting movements and verbal responses;

2. (b) difficulty in initiating and completing actions;

3. (c) increased reliance on physical or verbal prompting by others; and

4. (d) increased passivity and apparent lack of motivation.

Other abnormalities of behaviour often associated were:

1. (e) reversal of day and night;

2. (f) Parkinsonian features: tremor, eyerolling, dystonia, odd stiff posture, freezing in postures, etc.;

3. (g) excitement and agitation; and

4. (h) increase in repetitive, ritualistic behaviour.

Clinical assessment

For those seen at Elliot House, information was collected from an appropriate informant, usually one or both parents, using the Diagnostic Interview for Social and Communication Disorders (DISCO; further details available from the first author upon request). This is a semi-structured interview that enables the interviewer to obtain, in a systematic fashion, details concerning the medical history and the pattern of development from birth of a wide range of skills and atypical behaviour. It contains a section on associated psychiatric disorders and another on catatonic phenomena.

When the assessments were carried out in other locations, the same procedures were adopted as far as possible. In some cases, the diagnosis of an autistic spectrum disorder had already been firmly established. For these individuals, the purpose of the consultation was to consider how to manage challenging behaviour, sometimes including difficulties due to catatonic features. Relevant diagnostic information was collected from case notes, supplemented by informants. For the 14 individuals (2.8%) about whose early history no informant was available, as much information as possible was obtained from past case records. In all cases, the DISCO was used as the framework for recording details.

A study of interrater agreement has recently been completed for the DISCO, with the participation of parents of children who had not been seen at Elliot House. For over 80% of all the developmental and behavioural ratings made (515), kappa was equal to, or better than, 0.75 or, for the few ratings where kappa was not appropriate, agreement was 90% or above (further details available from the first author upon request).

Psychological assessment

Although associated cognitive deficits of any level of severity are very common, autistic spectrum disorders can occur in individuals of average or superior cognitive ability on formal intelligence tests (Reference RutterRutter, 1970; Reference Wing and GouldWing & Gould, 1979; Reference WingWing, 1996). Assessments of cognitive skills were carried out, using standardised tests appropriate for age and ability to cooperate. The subjects were observed in structured and unstructured situations. Because of the difficulties of testing individuals with catatonia, for this group the estimates of cognitive ability were based on performance before the onset of catatonia, using information obtained from case records and interviews with parents or care-givers. For the comparison group, the estimate was based on the findings when seen and assessed by the Elliot House team.

Type of residence

At the time when they were seen and assessed, individuals in the study were in four different types of residence: living independently; at home with parents; in a small residential home in the community; or in a hospital ward.

Statistical analysis

A one-way analysis of variance was used to compare ages. Otherwise, Pearson's χ² tests were used.

Prevalence among referrals

A total of 30 individuals with autistic spectrum disorders (6% of all referrals) met the above criteria for catatonia. Their ages when seen at Elliot House ranged from 15 to 50 years. Table 1 shows the numbers and percentages of these with catatonia among all referrals, by age group when seen. All of those with catatonia were aged 15 or above at referral. They represented 17% of all referrals in that age range.

Table 1 Ages when seen at Elliot House

Age group (years)	Total seen n	With catatonia
		n	(%)
1-4	90	-	(-)
5-9	159	-	(-)
10-14	82	-	(-)
15-19	65	12	(17)
20-24	48	8	(17)
25-29	19	3	(16)
30-34	20	5	(25)
35+	23	2	(9)
Total	506	30	(6)

A further eight individuals (five males (one with Down's syndrome) and three females, aged 10-36 years when seen) had occasionally had problems crossing thresholds and/or freezing during activity, but were not disabled enough to be included in the catatonic group. In two of these, the brief catatonic episodes had occurred only in early or middle childhood. In one, catatonic features were seen at school but not at home.

Characteristics of the group with catatonia

Age of onset

The ages of onset of the current episode of catatonia, obtained from the recollections of informants, are given in Table 2. For four individuals, the ages of onset could not be ascertained. For the rest, the majority started the current episode between 10 and 19 years of age. Five individuals had had brief episodes of slowness and freezing during childhood, before age 10.

Table 2 Ages of onset of catatonia

Age group (years)	n
1-4	-
5-9	-
10-14	7
15-19	16
20-24	2
25-29	1
Not known	4
Total	30

Manifestations of catatonic behaviour

The most common manifestations of catatonic behaviour seen in the group, each affecting seven or more individuals, are listed in Table 3. Most of the abnormalities of movement resulted in slowing or stopping activities, but episodes of excitement and sudden impulsive actions also occurred. Some could not stop actions once started. Incontinence resulted when the individual concerned did not initiate the movement needed to reach the toilet.

Table 3 Most frequent manifestations of catatonia

Catatonic manifestations	Feature present n
Essential criteria (slowness, difficulty initiating movements, needs prompts, passive)	30
Odd gait	27
Odd, stiff postures	19
Freezing	17
Impulsive acts	16
Difficulty crossing lines	16
Bizarre/psychotic	12
Sleep problems	10
Incontinence	10
Cannot stop actions	7
Excited phases	7

As shown in Table 3, 12 individuals showed bizarre behaviour that could not be classified under other headings. For example, two individuals would never use one arm and hand (the left in one case and the right in the other), although no physical reason could be found. One man walked the same route to the same destination each day in order to stand motionless, staring for 2 hours at a spot where a building used to be before it was pulled down. Others had occasional visual hallucinations or paranoid ideas that did not fit any particular diagnosis.

According to the accounts given by relatives or other carers, none had ever had the first-rank symptoms of schizophrenia. All showed abnormalities of speech, but these were indistinguishable from those found in autistic disorders. The quantity of speech was in all cases markedly reduced or absent when catatonia was present.

Comparison with a group without catatonia

The comparison group comprised 115 individuals with autistic spectrum disorders whose age range (when they were seen at Elliot House) was the same as that of those with catatonia (15 years and above), and whose clinical details were entered into a computer file. Twenty-two individuals in the same age range were excluded because they were not in the computer file for administrative reasons, not due to any bias in their clinical pictures. The eight with mild or previous catatonia mentioned above were also excluded.

Gender

There was an expected excess of males in both groups, somewhat more marked among those with catatonia. The difference between groups was not significant (see Table 4).

Table 4 Characteristics of the catatonia and comparison groups

Variable	Catatonia group (n 30)		Comparison group (n 115)		P
	n	(%)	n	(%)
Gender
Male	28	(93)	91	(79)	NS
Female	2	(7)	24	(21)
Diagnostic subgroup
Autism	11	(37)	32	(28)	NS
Atypical autism	5	(17)	8	(7)
Asperger syndrome	14	(47)	75	(65)
Social interaction
Aloof	5	(17)	18	(16)	<0.001
Passive	15	(50)	19	(17)
Active/odd	10	(33)	77	(67)
Level of cognitive ability
Severe learning disability	9	(30)	22	(19)	NS
Mild learning disability	9	(30)	19	(17)
Borderline/average	12	(40)	74	(64)
Expressive language
Impaired	16	(43)	30	(26)	0.008
Not impaired	14	(57)	85	(74)
Residence
Parents' home	9	(30)	70	(61)	<0.001
Own home	-	(-)	16	(14)
Care home	12	(40)	13	(11)
Hospital	9	(30)	16	(14)

Prevalence

As previously noted, the number of individuals with catatonia, as defined above, among Elliot House referrals was probably unusually high. The proportion of individuals with this type of deterioration in skills and behaviour should not, without further investigation, be considered as typical of autistic disorders in general. It is also possible that the factors found to be significantly associated with catatonia can be explained by referral bias. Nevertheless, the comparisons between those with and those without catatonia remain valid.

Factors involved in the development of catatonia

Catatonia was seen more often in those who had impaired expressive language, and those who were passive in social interaction, before the onset of catatonia. Within the group of those who developed catatonia, however, the number of catatonic features and the degree to which the catatonia limited everyday activities had no significant relationship to expressive language ability or type of social interaction.

In the majority of individuals in this study, the onset of severe catatonia occurred in the years from 10 to 19, although a few had also had brief episodes of freezing, or difficulty crossing thresholds, in childhood. Adolescence is associated with physical and psychological stresses. However, in more than half of the group studied, no particular precipitating cause could be identified, although they may have experienced stresses that were idiosyncratic to the individuals concerned but were not evident to the care-givers. Most adolescents with autistic disorders do not develop catatonia, although they too are likely to meet the same kinds of difficulties associated with growing up. It is possible that some individuals have an inherent vulnerability to developing catatonia, which becomes overt in response to stress.

Autistic disorders, catatonia and related motor disorders

The terms ‘catatonia’ and ‘autistic spectrum disorder’ refer to clusters of behavioural features. They can each be associated with a range of physical and psychological conditions. They are best regarding as effects of underlying causes and not as causal entities. They share the fuzziness inherent in concepts defined only by a mix of behavioural features, even when operational criteria have been standardised, as with the ICD-10 classification. Nevertheless, they are useful concepts in clinical practice. It is necessary to use appropriate methods of management and treatment of the overt behaviour when, as in the group described here, a treatable underlying cause cannot be identified.

Autistic conditions are developmental disorders present from birth or early in life. The concept of catatonia was developed in relation to behaviour observed in adults. However, there is a marked overlap of the behavioural features of the two disorders. For example, motor stereotypies, mannerisms, rituals, mutism, echolalia and negativism, among others, are described in catatonia (Reference Joseph, Joseph and YoungJoseph, 1992; Reference Bush, Fink and PetridesBush et al, 1996) as well as in autistic spectrum disorders (Rutter, Reference Rutter, Rutter and Schopler1978, Reference Rutter, Rutter and Hersov1985; Reference WingWing, 1996). This overlap in the clinical pictures, as well as the findings reported here, raises the question of the nature of the relationship between the two disorders.

In this context it is relevant to note that the manifestations of catatonia that were most common in the group described here overlap with those found in parkinsonism. Damasio & Maurer (Reference Damasio and Maurer1978) discussed the similarities between the motor phenomena of autism and of parkinsonism. Rogers (Reference Rogers1992) considered that a rigid division of motor disorders into ‘catatonic’ (psychiatric) and extrapyramidal (neurological) was not appropriate because of the high correlation between scores in the same individuals on the relevant scales. He concluded that there seems to be a continuously distributed array of disorders of movement, volition and behaviour, ranging from the relatively simple disorders of dyskinesia and parkinsonism to the complex disturbances of catatonia, all of which can be related to the extrapyramidal system. Lishman (Reference Lishman1997) described the clinical manifestations of encephalitis lethargica, the condition that was pandemic towards the end of the First World War and the 1920s. Lishman noted that catatonic phenomena could occur, and he mentioned all the behavioural features listed in the present paper.

The tendency to passivity in social interaction seen in some individuals before the onset of catatonia is, perhaps, a precursor of the lack of ability to initiate voluntary movement, which is typical of catatonia and parkinsonism. However, the findings do not corroborate the view of Leary & Hill (Reference Leary and Hill1996) that autism is a purely motor problem. The social and cognitive disabilities are as important as the motor aspects and cannot be explained away.

Other disorders affecting movement that can co-occur with autistic disorders include the pictures resembling obsessive-compulsive disorder (Reference Rutter, Rutter and HersovRutter, 1985), Tourette's syndrome (Reference Realmuto and MainRealmuto & Main, 1982) and attention-deficit hyperactivity disorder (Reference GillbergGillberg, 1992; Reference WingWing, 1996). The relationship between all these conditions and autistic disorders suggests that they have some aspect of their neuropathology in common.

Implication for care, treatment and research

Severe catatonia adds considerably to the difficulties of caring for individuals with autistic spectrum disorders, as shown by the numbers with catatonia who were in hospital placements. Admission was the result and not the cause of the catatonia.

It is important for clinicians to be aware of the possibility of catatonia when investigating reasons for deterioration in skills and behaviour occurring in adolescents and adults with autistic spectrum disorders. Conversely, the possibility of an underlying autistic disorder should be considered if an individual presents with catatonia. Possible physical or psychological causes should be investigated, and treated if found. In the absence of a treatable cause, there is no known cure for catatonia, but appropriate care and environmental management can help to alleviate the problems for the individual concerned and for their care-givers (further details available from the first author upon request).

Subjects for future research include investigation of the neuropathology, identification of early signs of vulnerability to exacerbation of catatonic features, the role of environmental stress, and methods of management and treatment.

CLINICAL IMPLICATIONS

• ▪ Catatonia develops in adolescence in a small proportion of individuals with autistic spectrum disorders.

• ▪ Recognition of catatonia in individuals with autistic spectrum disorders is necessary in order to institute appropriate management and care.

• ▪ The presence of an undiagnosed autistic spectrum disorder should be considered in any individual presenting with catatonia.

LIMITATIONS

• ▪ The prevalence rate of catatonia was based on referrals to a specialist clinic and is likely to be higher than that for a total population.

• ▪ The study was cross-sectional and does not provide information on future course and prognosis.

• ▪ Profiles based on all clinical features were not examined in the catatonic and comparison groups.