As it follows from our research, the patients with Asperger's syndrome and depression had the highest sense of loneliness, the lowest sense of purpose, the lowest sense of coherence, the lowest sense of control over life, and the highest values in existential vacuum. Both the autism spectrum and mood disorders have a dysfunctional effect on the broadly understood sense of self-efficacy. The autism spectrum is characterized by difficulties in establishing social relationships (25). Establishing relationships is also hindered by the impaired functioning of the so-called theory of mind in people on the autism spectrum, as described by Baron Cohen (26). The lack of the theory of mind makes it difficult to understand the intentions of another person, which results in difficulties in establishing relationships. On the other hand, withdrawal from social relations, anhedonia, and in extreme cases loss of the sense of meaning in life that may end in a suicide attempt are the features of a depressed mood (27). However, it is not known whether the co-occurrence of Asperger's syndrome and depression is an independent product of events, or whether Asperger's syndrome promotes the development of depression (28). Impaired ability to establish social contacts may, at least theoretically, contribute to the development of reactive mood disorders (29). Exploration of the link between depression and autism is hampered by the lack of validated psychometric tools to identify mood problems in people on the autism spectrum (30). The risk factors for mood disorders in people with autism are considered to largely overlap with those identified in the general population. However, they are probably exacerbated by the experience of autism and susceptibility to chronic stress associated with difficulties in social communication and sensory hypersensitivity typical of autism. Therefore, we assume that the studied group of people with Asperger's syndrome and depression may be more sensitive to rejection than people with Asperger's syndrome without depression. Hence, in the group of people with Asperger's syndrome and depression, we obtained lower values in terms of sense of meaning in life and low values within the range of scales measured by the LAP-R questionnaire. The distinction between depressive symptoms and autism spectrum symptoms is blurred by the recently discovered fact that the function of the mind is also disturbed in depression (31).
Based on the analysis of works from the PubMed database, our publication is probably one of the first to address the problem of the sense of meaning in life in people with Asperger's syndrome. However, articles on the problem of loneliness in people with Asperger's syndrome have already been published (14). One of these studies evaluated the relationship between friendship, loneliness and depressive symptoms in 35 people with Asperger's syndrome and 35 control subjects. People with Asperger's Syndrome reported poorer quality of best friendships and less motivation to develop them compared to the control group (14). They were also characterized by a higher sense of loneliness and more severe depressive symptoms. The authors of the discussed work suggest that an increased level of negative affect may be associated with the poor quality of social relationships in the studied group of people. However, the authors do not propose a psychological model of the correlation between the observed variables. A 2015 review of studies preliminarily indicates that group interventions in well-functioning people on the autism spectrum reduce the feelings of loneliness and alleviate the co-occurrence of other psychopathological symptoms, including depressive symptoms (32). Studies on the effectiveness of the UCLA PEERS program also demonstrated on a sample of 22 well-functioning adults with autism an improvement in social relationships and a reduction in feelings of loneliness in people participating in this program (33).
In all four groups we studied, loneliness and all dimensions of the LAP-R scale, except the death acceptance dimension, correlated positively with the severity of depression (BDI-II). The coefficients of these correlations reached relatively high values at p < 0.001. The above means that the psychological construct of depression is similar to the psychological construct of the sense of loneliness and lack of meaning in life. It is puzzling that acceptance of death does not correlate with the results of the Beck Depression Inventory. This fact is explained by the well-known clinical observation that not every depressed patient has suicidal ruminations and acceptance of non-existence associated with the end of existence. A large proportion of patients with depression are afraid of death. Suicidal thoughts occur in severe depression, in exacerbations, and only patients in a stable state of mood disorders were qualified for our study. Our study should probably be repeated in a clinical ward where patients with suicidal ideations are hospitalized.
Due to the insufficient number of women representing the group with Asperger's syndrome and depression (N = 12), as well as with Asperger's syndrome (N = 3), statistical analysis could not be performed.
Due to the very similar age of all participants in the study, in all 4 groups, the results of the analysis of the correlation between the DJGLS scales and dimensions in the LAP-R scale and age were statistically insignificant, or statistically significant, but poorly correlated (Table S5 in the Supplement).
Limitations of the study
Too small group of people participating in the study prevented us from analyzing the studied variables in terms of gender and age, although Asperger's syndrome is believed to be several times more common in men than in women (34). In the Polish population of people in the late adult phase, the estimated diagnosis of autism spectrum disorder is significantly underestimated, because the psychiatrists’ awareness of the existence of autism spectrum disorders appeared with the introduction of the ICD-10 classification in Poland. Seniors on the autism spectrum were usually classified as having intellectual disabilities. Therefore, our study involved only young adults diagnosed in childhood after the introduction of ICD-10 in Poland. What is missing from our paper is the reference to other research using psychometric tools such as DJGLS and LAP-R to study people on the autism spectrum and mood disorders. Such works either do not exist or are not available in English-language literature.
The selection of patients for individual groups was deliberate and was not random. It is interesting whether we would get similar results in large-population studies where patient selection would be random.