Cognitive Impairment in Neurodegenerative Disorders

Neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease dementia, dementia with Lewy bodies and frontotemporal dementia are characterised by progressive loss of neurons and synaptic function, leading to deficits in memory, attention, executive function and visuospatial ability. Cognitive impairment emerges from multifactorial pathologies including protein misfolding, cholinergic and dopaminergic deficits, network desynchronisation and regional atrophy. Early stages often present as mild cognitive impairment (MCI), during which subtle alterations in brain activity and connectivity can be detected with neurophysiological and neuroimaging tools. As the disease advances, compensatory network changes become insufficient, yielding frank dementia. Advances in quantitative electroencephalography (QEEG), magnetic resonance imaging and fluid biomarkers have illuminated the dynamic interplay between neural oscillations, large-scale networks and neurotransmitter integrity, offering objective markers of disease progression. Improved characterisation of spectral slowing, network topology and cholinergic dysfunction promises earlier diagnosis, patient stratification and the design of targeted interventions such as neuromodulation and precision pharmacotherapy. The global ageing population underscores the urgent need for scalable, noninvasive biomarkers to identify at-risk individuals and to monitor therapeutic efficacy across diverse clinical settings.

Research from Nature Portfolio

Recent work has characterised alterations in large-scale network architecture by analysing minimum spanning tree (MST) metrics derived from resting-state electroencephalography. In patients with Lewy body dementia and Parkinson’s disease dementia, connectivity within alpha and high-theta bands was markedly reduced and MST topology became more random compared with healthy controls and Alzheimer’s disease, reflecting diminished network efficiency and impaired neural synchronisation. These alterations were observed in frontal, temporal and parietal regions and correlated with cognitive fluctuations, suggesting that network randomisation may serve as an electrophysiological signature distinguishing synucleinopathies from pure amyloid-tau pathology.

Cognitive Impairment in Neurodegenerative Disorders publication trend

The graph below shows the total number of articles in cognitive impairment in neurodegenerative disorders across all publications each year (not limited to Nature Index journals).

Technical terms

Neurodegenerative disorders: Conditions characterised by progressive loss of neuronal cells and synapses, leading to functional impairments in cognition and movement.

Cognitive impairment: Diminished capacity in domains such as memory, attention, language and executive function beyond that expected for age and education.

Mild cognitive impairment (MCI): A transitional cognitive state between normal ageing and dementia, marked by measurable deficits in one or more cognitive domains without significant impact on daily living.

Electroencephalography (EEG): A noninvasive technique that records electrical activity of the brain via scalp electrodes, used to assess neural oscillations.

Quantitative EEG (QEEG): Computational analysis of EEG signals to extract spectral power, connectivity and network metrics for objective assessment of brain function.

Functional connectivity: Statistical relationships or synchrony between neural signals from different brain regions, reflecting coordinated activity within networks.

Dominant frequency: The frequency band exhibiting the highest power in the EEG spectrum, often shifting toward slower rhythms in cognitive decline.

References

1. Resting-state EEG measures cognitive impairment in Parkinson’s disease. npj Parkinson's Disease (2024).
2. QEEG Signatures are Associated with Nonmotor Dysfunctions in Parkinson's Disease and Atypical Parkinsonism: An Integrative Analysis. Aging and Disease (2023).
3. Capturing the Abnormal Brain Network Activity in Early Parkinsons Disease With Mild Cognitive Impairment Based on Dynamic Functional Connectivity. IEEE Transactions on Neural Systems and Rehabilitation Engineering (2023).
4. Electroencephalographic derived network differences in Lewy body dementia compared to Alzheimer’s disease patients. Scientific Reports (2018).