Code for: Arithmetic deficits in Parkinson’s Disease? – A Registered Report

Neurodegenerative diseases such as Parkinson’s Disease (PD) have a huge impact on patients, caregivers, and the health care system. Until now, diagnosis of mild cognitive impairments in PD has been established based on domain-general functions such as executive functions, attention or working memory. However, specific numerical deficits observed in clinical practice have not yet been systematically investigated. PD-immanent deterioration of domain-general functions and domain-specific numerical areas suggests mechanisms of both primary and secondary dyscalculia. The current study systematically investigated basic number processing performance in PD patients for the first time, targeting domain-specific cognitive representations of numerosity and the influence of domain-general factors. The overall sample consisted of patients with a diagnosis of PD, according to consensus guidelines, and healthy controls. PD patients were stratified into patients with normal cognition (PD-NC) or mild cognitive impairment (level I-PD-MCI based on cognitive screening). Basic number processing was assessed using transcoding, number line estimation, and (non-) symbolic number magnitude comparison tasks. Discriminant analysis was employed to assess whether basic number processing tasks can differentiate between a healthy control group and both PD groups. All participants were subjected to a comprehensive numerical and a neuropsychological test battery, as well as sociodemographic and clinical measures. Results indicate a profile of preserved (verbal representation) and impaired (magnitude representation, place × value activation) function in PD-MCI, hinting at basal ganglia dysfunction affecting numerical cognition in PD. Numerical deficits could not be explained by domain-general cognitive impairments, so that future research needs to incorporate domain-specific tasks of sufficient difficulty.

Elderly people and patients with neurodegenerative diseases such as Parkinson’s Disease (PD) immensely rely on arithmetic skills to lead an independent life. Activities such as medication management, financial transactions or using public transport require intact abilities to manipulate numbers with different arithmetic operations. However, research on cognitive deficits in PD has been focussing on domain-general functions such as executive functions, attention or working memory so far – largely neglecting potential domain-specific aspects of numerical cognition (e.g., carry or problem size effect). These aspects should be addressed, as PD-immanent deterioration of domain-specific numerical areas and domain-general functions suggests mechanisms of both primary and secondary (mediated by other cognitive deficits) arithmetic deficits, respectively. The current study systematically investigated arithmetic performance and effects in PD patients differing in cognitive impairment for the first time, targeting domain-specific cognitive representations of arithmetic as well as the influence of domain-general factors. Besides healthy controls (HC), PD patients with normal cognition (PD-NC) and PD patients with mild cognitive impairment (PD-MCI) were compared in arithmetic performance in the four basic operations (addition, subtraction, multiplication, division). The deficits consisted of problems in two-digit addition and subtraction and PD-MCI, as well as delayed arithmetic fact retrieval for single-digit multiplication and division in PD-NC and PD-MCI. Deficits were not domain-specific, as arithmetic effects (problem size, carry, and borrow effects) did not differ between the groups. Discriminant analyses showed that performance in addition, multiplication and division tasks could differentiate between PD-NC and PD-MCI. The study results help us to understand the underlying mechanisms of arithmetic deficits faced by PD patients in daily life.

Elderly people and patients with neurodegenerative diseases such as Parkinson’s Disease (PD) immensely rely on arithmetic skills to lead an independent life. Activities such as medication management, financial transactions or using public transport require intact abilities to manipulate numbers with different arithmetic operations. However, research on cognitive deficits in PD has been focussing on domain-general functions such as executive functions, attention or working memory so far – largely neglecting potential domain-specific aspects of numerical cognition (e.g., carry or problem size effect). These aspects should be addressed, as PD-immanent deterioration of domain-specific numerical areas and domain-general functions suggests mechanisms of both primary and secondary (mediated by other cognitive deficits) arithmetic deficits, respectively. The current study systematically investigated arithmetic performance and effects in PD patients differing in cognitive impairment for the first time, targeting domain-specific cognitive representations of arithmetic as well as the influence of domain-general factors. Besides healthy controls (HC), PD patients with normal cognition (PD-NC) and PD patients with mild cognitive impairment (PD-MCI) were compared in arithmetic performance in the four basic operations (addition, subtraction, multiplication, division). The deficits consisted of problems in two-digit addition and subtraction and PD-MCI, as well as delayed arithmetic fact retrieval for single-digit multiplication and division in PD-NC and PD-MCI. Deficits were not domain-specific, as arithmetic effects (problem size, carry, and borrow effects) did not differ between the groups. Discriminant analyses showed that performance in addition, multiplication and division tasks could differentiate between PD-NC and PD-MCI. The study results help us to understand the underlying mechanisms of arithmetic deficits faced by PD patients in daily life.