Identification of body parts in Alzheimer's disease: evidence for a body schema hypothesis

Differences by cognitive impairment in detailed processes for basic activities of daily living in older adults with dementia

BACKGROUND

Impairment of activities of daily living in patients with dementia has a fundamental and lasting impact on their quality of life and requires a detailed assessment. This study investigated to clarify characteristic of basic activities of daily living (BADL) processes with the severity of cognitive impairment in community-dwelling older adults with dementia using the Process Analysis of Daily Activity for Dementia (PADA-D).

METHODS

Participants were recruited from outpatient departments of 24 hospitals, daycare centres, and home rehabilitation services in Japan. The severity of cognitive impairment was determined using the Mini-mental State Examination (mild: score ≥ 20; moderate: 10 ≤ score < 20; severe: score < 10). Patient's BADL were assessed according to the PADA-D by observation of the occupational therapist and interviews with family members. Basic information and the scores of BADL items of the PADA-D were compared between the three groups. Subsequently, we compared the percentage of independent or non-independent processes included in the sub-items of BADL in the PADA-D.

RESULTS

A total of 143 patients were included in the analysis. Performance on BADL was shown to decrease significantly with increasing severity of cognitive impairment. The percentage of all BADL processes performed ranged from 58% to 100% in mild, 38% to 97% in moderate, and 0% to 88% in severe. Some of the processes included in BADL of PADA-D showed no significant differences in independence between the three groups.

DISCUSSION/CONCLUSION

Most BADL processes differed with respect to different independence rates depending on the severity of cognitive impairment of the older adults with dementia. However, some BADL processes were not associated with the severity of cognitive impairment. Our findings may suggest that a detailed BADL assessment of patients with dementia is useful in terms of caregiver education to avoid excessive caregiving and in predicting BADL impairment.

Body representation in patients after vascular brain injuries

Neuropsychological literature suggests that body representation is a multidimensional concept consisting of various types of representations. Previous studies have demonstrated dissociations between three types of body representation specified by the kind of data and processes, i.e. body schema, body structural description, and body semantics. The aim of the study was to describe the state of body representation in patients after vascular brain injuries and to provide evidence for the different types of body representation. The question about correlations between body representation deficits and neuropsychological dysfunctions was also investigated. Fifty patients after strokes and 50 control individuals participated in the study. They were examined with tasks referring to dynamic representation of body parts positions, topological body map, and lexical and semantic knowledge about the body. Data analysis showed that vascular brain injuries result in deficits of body representation, which may co-occur with cognitive dysfunctions, but the latter are a possible risk factor for body representation deficits rather than sufficient or imperative requisites for them. The study suggests that types of body representation may be separated on the basis not only of their content, but also of their relation with self. Principal component analysis revealed three factors, which explained over 66% of results variance. The factors, which may be interpreted as types or dimensions of mental model of a body, represent different degrees of connection with self. The results indicate another possibility of body representation types classification, which should be verified in future research.

Processing of Self versus Non-Self in Alzheimer's Disease

Despite considerable evidence for abnormalities of self-awareness in Alzheimer's disease (AD), the cognitive mechanisms of altered self-processing in AD have not been fully defined. Here we addressed this issue in a detailed analysis of self/non-self-processing in three patients with AD. We designed a novel neuropsychological battery comprising tests of tactile body schema coding, attribution of tactile events to self versus external agents, and memory for self- versus non-self-generated vocal information, administered in conjunction with a daily life measure of self/non-self-processing (the Interpersonal Reactivity Index). Three male AD patients (aged 54-68 years; one with a pathogenic mutation in the Presenilin 1 gene, one with a pathogenic mutation in the Amyloid Precursor Protein gene, and one with a CSF protein profile supporting underlying AD pathology) were studied in relation to a group of eight healthy older male individuals (aged 58-74 years). Compared to healthy controls, all patients had relatively intact tactile body schema processing. In contrast, all patients showed impaired memory for words previously presented using the patient's own voice whereas memory for words presented in other voices was less consistently affected. Two patients showed increased levels of emotional contagion and reduced perspective taking on the Interpersonal Reactivity Index. Our findings suggest that AD may be associated with deficient self/non-self differentiation over time despite a relatively intact body image: this profile of altered self-processing contrasts with the deficit of tactile body schema previously described in frontotemporal dementia associated with C9orf72 mutations. We present these findings as a preliminary rationale to direct future systematic study in larger patient cohorts.