This new Lille Apathy Rating Scale (LARS) was built on the conceptual basis of Marin's apathy evaluation scale (AES) but sought to remove various practical difficulties in using the latter. In particular, we have noticed first, a lack of standardisation in the administration and scoring procedures (because of the semistructured nature of the AES); second, variations in interpretation owing to multiple sources of informants; and third, possible sources of error because of fluctuation in the positive/negative orientation of questions. Moreover, we have also noticed a heterogeneous weighting of the items in relation to the main psychological domains. In order to enhance standardisation, improve stability, and reduce subjective interpretations during scoring, we adopted a dichotomous scale. Moreover, the nine domains of interest were equally weighted in the final score, enabling the generation of subject profiles. Question by question examination did not reveal floor or ceiling effects or extremely low or high inter‐item correlations that would indicate incongruence or redundancy. This internal consistency was reinforced by relatively high reliability coefficients, suggesting that the scale indeed deals with a single, coherent construct.
In addition to the global assessment of apathy, the LARS also revealed a structure whose factors were interpreted as representing intellectual curiosity, action initiation, emotion, and self awareness. In fact, several studies2,4,6,17,18
have proposed definitions which incorporate distinct components of apathy (behavioural, cognitive, and emotional) and our results agree with and reinforce these suggestions, as these same three realms emerged from our analysis. Nevertheless, our data also generated a fourth factor, representing a reduction in self awareness and impaired behavioural adjustment to social life. This factor seemed to emerge in relation to certain specific characteristics of patients with cognitive decline.
Discriminating between depression and apathy has always been a tricky issue. Nevertheless, some studies have addressed this problem. For instance, Marin et al19
evaluated apathy and depression in patients with either Alzheimer's disease, stroke, or major depression. Although apathy and depression generally correlated within the groups, absolute scores varied considerably (and independently) between groups. Levy et al20
found the same disease specific relation using the NPI and concluded that the presence of one condition did not predict the presence of the other. Pluck and Brown3
drew very similar conclusions: although the symptoms can dissociate within individual patients, comorbid depression and apathy appeared to have an additive effect on symptoms such as cognitive dysfunction. Our data seem to be compatible with published reports: the correlation between LARS and MADRS scores is clearly explained by the latter's dysphoric apathy subscale, which covaries with the LARS IC dimension (and, to a lesser extent, with AI). Moreover, the simultaneous presence of these two symptoms indicated the Parkinson's disease patients with the worst scores on the LARS. In practical terms, distinguishing apathy from depression implies that one should consider both the LARS and the MADRS scores: extremely low scores on both scales indicate patients with little suspicion of either condition; extremely high scores on both scales indicate patients with a high suspicion of both conditions; depressed patients should present a relatively high MADRS score with a relative low LARS score, whereas a relatively low MADRS score and a relatively high LARS score predict the presence of apathy in the absence of depression.
The main goal of this study was to provide a useful tool (meeting the usual psychometric prerequisites) for the assessment of apathy. We demonstrated that the LARS has very satisfactory inter‐rater and test–retest reliability. Moreover, the establishment of excellent concurrent and criterion related validity was a major step in proving the value of LARS as a screening test. Furthermore, we proposed several cut off scores with good specificity and sensitivity. The comparison with Marin's AES criterion related validity was arduous, because we found several proposed AES cut off values.3,21,22
However, by opting for a cut off value corresponding to the mean AES score for the normal control group minus 2.5 SD, our sensitivity and specificity values showed that the LARS provided slightly more reliable validity. Finally, the four‐class severity system may provide greater sensitivity by enabling precise measurements in treatment efficacy studies or, more generally, during patient follow up.
In the current version of the LARS, all input information is obtained from the patient. In patients with anosognosia (who may thus underrate their symptoms), this may constitute a limitation. It is useful to obtain information from an informant in such cases, and we are currently working on an informant version of the LARS.
Our results showed that apathy is frequent in Parkinson's disease and that higher apathy levels are observed in patients with cognitive complications. The observed prevalence of 29% was within the range of previously reported values.3,7,8
The LARS is a reliable and practical instrument for assessing the multiple dimensions of apathetic syndrome. Its psychometric qualities appear to make it particularly suitable for assessing changes in the manifestations of apathy: in the future, the scale could thus constitute an interesting outcome variable for evaluating the efficacy of potential apathy treatments. Further studies will have to demonstrate the ability of the LARS to specify the apathy profile of different patient groups in relation to a given disease aetiology or severity level.