Emotional Lability in MND: Relationship to cognition and psychopathology and impact on caregivers

Abstract

Emotional Lability (EL) is a well recognized symptom of cortico-bulbar pathway dysfunction in Motor Neuron Disease/Amyotrophic Lateral Sclerosis (MND/ALS), and is reported to occur in 19-49% of patients. The Emotional Lability Questionnaire (ELQ), is specifically designed to detect EL as reported by MND patients and as observed by their carers. The aims of this study were to 1) validate the Italian version of the ELQ; 2) investigate the relationship between EL and presence of cognitive dysfunction; 3) investigate the relationship between EL and presence of psychopathology. Forty one MND patients, 39 caregivers and respective control groups composed of 39 subjects and 39 partners/friends were tested. The Italian version of the ELQ was found to have good psychometric properties. Seventy-one per cent of patients reported suffering from EL. Correlations were found between bulbar involvement and EL, and between bulbar involvement and low performance on tests of fluid intelligence and working memory. However, the cognitive profile did not correlate with any aspect of EL. The findings suggests that damage to different neurological pathways underlie cognitive change and EL, which supports the concept of MND/ALS as a multisystem disorder. Moreover the outcomes suggest that EL affects patients' everyday life with the increased anxiety and emotional frailty. The findings suggest that those involved in the care of MND patients should be more aware of the effects of EL in the management of the disease.

Introduction

Emotional Lability (EL), is the involuntary occurrence of laughter and crying in the absence of a corresponding change in affect. It was first reported in Motor Neuron Disease (MND) in the last century and was found to occur in 19%-49% of Amyotrophic lateral Sclerosis (ALS) patients [1], [2], the most common form of MND. EL is most often present in patients who have pseudo-bulbar symptomatology [1], [3]. Nevertheless, few studies have undertaken a systematic investigation of this phenomenon and hence it remains poorly understood.

In 1997 Moore and colleagues validated the CNS-LS (Centre of Neurological Study-Lability Scale) in ALS patients; a seven-item, self report measure of affective lability composed of two subscales measuring labile laughter and labile tearfulness [4]. The CNS-LS represents a good clinical instrument, but lacks the details necessary to permit a thorough exam of the nature and the pervasiveness of emotional lability in the MND population. More recently, Newsom-Davies and colleagues [3] developed the Emotional Lability Questionnaire (ELQ), a measurement scale specifically designed to assess MND patients which includes a self-rated version for patients and independent-rated version for caregivers. The ELQ was modified from the Pathological Laughter and Crying scale [5] which was first developed for stroke patients. The ELQ presents good psychometric properties and in depth exploration of emotion and expression, such as the introduction of the ‘abnormal smiling’ subscale. We set out to validate an Italian version of the ELQ, to produce a measure able to detect lability in an Italian population of MND patients, and to distinguish between pathological laughing, crying and smiling.

A second aim of this study was also to investigate the relationship between EL and cognitive deficits, which are found in some patients with MND. Although EL can be found in patients with frontal and temporal lobe involvement, the traditional view is that EL is due to damage to pathways that arise in the motor areas of the cerebral cortex and descend to the brainstem and inhibit putative centres for laughter and crying. Recent neuroanatomical findings suggest that the critical areas are in the cerebro-ponto-cerebellar pathways [6], [7]. The abnormal cognitive profile found in MND/ALS is well-known, and consists of predominant executive dysfunction and in some cases language and memory dysfunction [8], [9], [10], [11], [43], [44], [45], [46], [47]. Visuospatial functions appear well preserved. This profile of impairment is consistent with frontotemporal involvement as found in neuroimaging studies of MND patients [12], [13], [14]. In one of the largest studies of cognition in ALS to date [15], 47% of patients showed executive dysfunction, and 15% of them had severe cognitive impairment with features that were consistent with fronto-temporal dementia. The presence of cognitive impairment in MND appears more prominent in patients with pseudo-bulbar palsy [10], [16]. In previous studies emotional lability was also found to significantly correlate with bulbar scores [3]. However, the relationship between EL and cognitive dysfunction in MND has received little attention other than a small study reported by McCullagh et al. [17] in which a difference was found between 8 ALS patients with EL and 10 patients without, in errors on Wisconsin Card Sorting Test.

Moreover, the relationship between EL and psychopathology has not previously been investigated in MND. Estimated prevalence rates for depression or mild depressive-symptomatology has appeared low, between 0-44% in MND populations [18], [19], [20], [21]. In recent studies depression has appeared to be relatively more common (prevalence rates up to 50%), as were other forms of psychological distress, and was not associated with illness severity and functional status [22]. Estimated prevalence rates for anxiety have ranged 11-30% [23], [24], [25]. A number of studies have shown the importance of including patients' families in psychological research on MND. Social factors have been reported to be the best predictor of ALS patients' self-esteem during the disease [26]. In addition Gauthier et al. [27] found that patients' level of disability and caregivers' depression were related with caregivers' perception of burden. While Goldstein [23] showed that carers also demonstrated signs of anxiety and depression, with the latter correlating with aspects of the patients' functional impairment. Carers depression and strain appeared to be related to their attributional style and perceived strain was greater in carers who viewed their partners' illness as having a more global impact on their lives [28]. Hence, our third aim was to investigate the relationship between EL and psychological status in patients and their caregivers.