Neurological Soft Signs and Psychopathology in Chronic Schizophrenia: A Cross-Sectional Study in Three Age Groups

Abstract

As established in a wealth of studies subtle motor and sensory neurological abnormalities or neurological soft signs (NSS) are frequently found in patients with schizophrenia at any stage of their illness. However, the potential impact of chronicity and age on NSS was scarcely investigated. Therefore, we assessed NSS in 90 patients with subchronic (n = 22) or chronic (n = 68) schizophrenia and in 60 healthy controls who were assigned to three age groups (18–29, 30–49, and +50 years). NSS were measured on the Heidelberg Scale, psychopathological symptoms including apathy were rated on established instruments. As demonstrated by analysis of variance, NSS scores in patients were significantly (p < 0.05) increased relative to healthy controls. Significant age effects arose in all NSS subscores, with older subjects scoring well above the younger ones. These age effects were more pronounced in patients than controls, indicating that NSS in chronic schizophrenia exceed age-associated changes. Moreover, the NSS scores in patients were significantly associated with duration of illness, thought disturbance, positive symptoms, and apathy. These results were confirmed after age/duration of illness and years of education were partialed out and via regression analyses. Our findings conform to the hypothesis that NSS are associated with chronicity of the disorder as indicated by the correlations of NSS with both, duration of illness and apathy. The correlations between NSS and positive symptoms/thought disturbance correspond to the fluctuation of positive symptoms during the course of the disorder. The significantly more pronounced age effects on NSS in patients may either point to ongoing cerebral changes or to a greater susceptibility of patients toward physiological age effects, which may be mediated among other factors by a lower cognitive reserve.

Neurological soft signs (NSS) and brain morphology in patients with chronic schizophrenia and healthy controls

“…Moreover, as in the present study we could not find significant correlations between antipsychotic dosage and NSS scores in a recent publication with 90 chronic schizophrenic patients [10]. Additionally, patients with extrapyramidal side effects, tardive dyskinesia, parkinsonian signs and abnormal involuntary movements were not included in the present study.…”

“…Moreover, none of the psychopathological indices correlated significantly to NSS total scores, except AES sumcores, which can be interpreted as reflection of the chronicity of the disorder in our sample. As apathy can arise in various severe neuropsychiatric disorders including schizophrenia, mild cognitive impairment and Alzheimer's disease [34,63] it can be seen as a much broader concept than negative symptoms [10].…”

“…The diminished and different correlation patterns between GM and NSS scores in our control group in contrast to the patients can be explained with their attenuated variance of NSS, which are rather low and stable over time. It has been shown that NSS in healthy controls may refer to age, level of education or less developed skills [10,21,36,80]. Further evidence that NSS in patients with schizophrenia and healthy controls may be based on different pathogenetic factors came from the Northern Finland 1966 general population birth cohort study: Infant motor development was rated at age 1 year and related to cerebral changes (MRI) at age 33-35 years.…”

“…Elevated levels of NSS are frequently found in patients with schizophrenia at any stage of their illness as well as-although to a lower extent-in relatives of patients with schizophrenia [3][4][5][6]. NSS are associated with negative symptoms and cognitive impairments, severity and persistence of psychopathological symptoms and poor social functioning, but seem to be relatively independent of antipsychotic medication [3,5,[7][8][9][10].…”

Patterns of co‐altered brain structure and function underlying neurological soft signs in schizophrenia spectrum disorders

“…In the present study, we have strictly matched the two groups according to age, because previous studies on age‐specific NSS level differences in schizophrenia showed contradictory results (Bombin, Arango, & Buchanan, ): While the majority of earlier studies could not identify any effects of age on NSS scores in SZ (Bartko, Zador, Horvath, & Herczeg, ; Buchanan & Heinrichs, ; Lane et al, ; Mohr et al, ), a number of studies showed that NSS levels might increase with age suggesting a progressive worsening of sensorimotor functioning (Cuesta, Peralta, & de Leon, ; Griffiths, Sigmundsson, Takei, Rowe, & Murray, ; Herold et al, ). Further, our study did not include duration of illness (DOI) as a covariate in the statistical analyses, because the question whether NSS are early markers of motor dysfunction preceding the illness onset or consequences of progressive worsening are not conclusively clarified yet.…”