2.2. Assessment Instruments

Patients were classified according to Hoehn–Yahr (H&Y) stage [51] by a movement disorder specialist. Disease duration was calculated as years since onset of cardinal motor symptoms. LEDDs were calculated according to the standard formula [52].

Two instruments were used to assess the SC domains of emotional processing, social reasoning, ToM, and decision-making [6–9, 53].

The COGSOC battery [10, 54] was created to provide a clinical instrument for assessment of SC in adults with a range of neurodegenerative and neuropsychiatric conditions. This instrument comprises seven subtests: five original subtests including two causal relationships comprehension tasks (causes and consequences), a visual absurdities identification task, a social judgment ability task, and a decision-making scale completed by caregivers and two known SC paradigms: denomination of Ekman's Pictures of Facial Affect (POFA) and a physical adaptation of the Iowa gambling task (IGT) according to the specifications of Bechara et al. [53]. The battery assesses three SC domains (i.e., emotional processing, social reasoning, and decision-making). The reliability coefficient (α) for the battery is 0.9, and for the subtests, it ranges between 0.7 and 0.9. The COGSOC construct validity was analyzed through exploratory factor analysis, which demonstrated that causal relationships comprehension (causes and consequences), visual absurdities identification, and social judgment tasks were grouped as one factor (social reasoning); POFA remained alone as a factor (emotional processing), and finally, the IGT and the decision-making scale was grouped in a third factor (decision-making). The battery was created for use in Mexican adult population and its psychometric properties, including difficulty level, discrimination capacity, and reliability of each item, and subtest has been tested [54]. Table 1 provides further information on the purpose and characteristics of the battery's subtests. Figure 1 provides examples of the illustrations used in the causal relationships comprehension, visual absurdities identification, and social judgment ability subtests. The subtests are purposely designed to present most stimuli through thematic illustrations, reducing the load on short-term and working memory, which is deemed important when assessing PD population.

Examples of the COGSOC illustrations used in the causal relationships comprehension, absurdity identification, and social judgment ability subtests. The illustrations presented to patients are in color. (a) Causal relationships comprehension part A-causes: participants are asked “what has most probably happened immediately before this scene?” (b) Causal relationships comprehension part B-consequences: participants are asked “what has most probably happened immediately after this scene?” (c) Absurdity identification: participants are requested to find everything they consider wrong, nonsensical, or absurd. (d) Social judgment: in this item, participants were told “this is a fast cashier line and the lady at the front of the line has more items than that are permitted in her cart, what is the best course of action for the people in line?”

Description of the assessment instruments.

COGSOC, social cognition battery; SC, social cognition; POFA, Pictures of Facial Affect; ToM, theory of mind; IGT, Iowa gambling task; RME, reading the mind in the eyes.

The revised version of the “Reading the Mind in the Eyes” (RME) test in Spanish [58, 59] was used to assess ToM. The instrument was created to assess subtle changes in ToM capacity in adults and is considered an advanced ToM test. It has been used widely to measure affective ToM in the PD population [28, 61, 62] because it requires inference of what a person is feeling rather than the person's beliefs or motivations.

Although the POFA and RME tests could seem similar, it is important to consider that the POFA test measures the ability to perceive basic emotions, which are considered universal, are biologically determined, and can be automatically appraised or perceived [55]. In contrast, emotions included in the RME test are secondary or “high-order” emotions. To recognize secondary emotions, one requires cognitive elaboration of a social context and an inference of what the person is feeling. These secondary emotions arise from subtle combination of basic emotions and are considered “complex mental states” [58].