Enhanced slow wave activity has been found in stroke patients, schizophrenia, depression, Alzheimer's disease and post-traumatic stress disorder, but the relationship between slow wave activity and healthy aging is as yet unclear. We investigated the relationship between age and the frequency at which focal generators of delta waves appear in the healthy cerebral cortex, as well as whether this measure is associated with cognitive performance. Resting MEG was assessed in 53 healthy individuals aged 18-53. Focal slow wave generator dipole density decreased with age, but there was no relationship between dipole density and cognitive performance. These results emphasize the necessity of controlling for age in studies of slow wave activity in psychopathology.

BackgroundResting-state recordings are characterized by widely distributed networks of coherent brain activations. Disturbances of the default network - a set of regions that are deactivated by cognitive tasks and activated during passive states - have been detected in age-related disorders such as Alzheimer's or Parkinson's disease but alterations in the course of healthy aging still need to be explored.ResultsUsing magnetoencephalography (MEG), the present study investigated how age-related functional resting-state brain connectivity links to cognitive performance in healthy aging in fifty-three participants ranging in age from 18 to 89 years. A beamforming technique was used to reconstruct the brain activity in source space and the interregional coupling was investigated using partial directed coherence (PDC). We found significant age-related alterations of functional resting-state connectivity. These are mainly characterized by reduced information input into the posterior cingulum/precuneus region together with an enhanced information flow to the medial temporal lobe. Furthermore, higher inflow in the medial temporal lobe subsystem was associated with weaker cognitive performance whereas stronger inflow in the posterior cluster was related to better cognitive performance.ConclusionThis is the first study to show age-related alterations in subsystems of the resting state network that are furthermore associated with cognitive performance.

Abstract:We investigated the development of large-scale functional networks over the lifespan by examining resting MEG of 53 healthy participants aged 18-89. Results show differential developments across the lifespan for low and high frequency networks. Delta frequency (2-4 Hz) networks decrease in size, while beta/gamma frequency (16 Hz) networks increase in size with age. The right frontal lobe and bilateral temporal areas were found to be important relay stations in high frequency networks. Normal age-related declines in visual memory and visuoconstructive capabilities were associated with the age-related increase of functional connectivity in both temporal lobes.

BackgroundThe hippocampus is a brain region that is particularly affected by age-related morphological changes. It is generally assumed that a loss in hippocampal volume results in functional deficits that contribute to age-related cognitive decline. In a combined cross-sectional behavioural and magnetoencephalography (MEG) study we investigated whether hippocampal-associated neural current flow during a transverse patterning task - which requires learning relational associations between stimuli - correlates with age and whether it is modulated by cognitive competence.ResultsBetter performance in several tests of verbal memory, verbal fluency and executive function was indeed associated with higher hippocampal neural activity. Age, however, was not related to the strength of hippocampal neural activity: elderly participants responded slower than younger individuals but on average produced the same neural mass activity.ConclusionsOur results suggest that in non-pathological aging, hippocampal neural activity does not decrease with age but is rather related to cognitive competence.

Physiological β-amyloid autoantibodies (Aβ-autoantibodies) are currently investigated as potential diagnostic and therapeutic tools for Alzheimer’s disease (AD). In previous studies, their determination in serum and cerebrospinal fluid (CSF) using indirect ELISA has provided controversial results, which may be due to the presence of preformed Aβ antigen-antibody immune complexes. Based on the epitope specificity of the Aβ-autoantibodies, recently elucidated in our laboratory, we developed (a) a sandwich ELISA for the determination of circulating Aβ-IgG immune complexes and (b) an indirect ELISA for the determination of free Aβ-autoantibodies. This methodology was applied to the analysis of serum samples from healthy individuals within the age range of 18 to 89 years. Neuropsychological examination of the participants in this study indicated non-pathological, age-related cognitive decline, revealed especially by tests of visual memory and executive function, as well as speed-related tasks. The ELISA serum determinations showed significantly higher levels of Aβ-IgG immune complexes compared to free Aβ-autoantibodies, while no correlation with age or cognitive performance of the participants was found.

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Cognitive decline in aging has been associated with the combined effects of diminishing functions of peripheral senses and diminished cognitive activation. Both effects are associated with loss of neural adaptation and failure to exploit the potential for neuroplastic adaptation. Consequently, reduced or noisy processing, weakened neuromodulatory control and negative learning actively degrade the brain's circuitry and functional architecture. Previous attempts to prevent or delay cognitive decline in normal or pathological aging focused on higher cognitive processes like mnemonic strategies. Cognitive improvements were moderate and did not generalize to other cognitive domains. In contrast, recent studies suggest that neuroplastic remodeling of representational cortex in order to adjust to age-related alterations in sensory fidelity might prevent and even reverse central degradation.We describe the theoretical and scientific background of an innovative computer-based auditory discrimination training, which is based on the principles of cortical reorganization in order to renormalize functions degraded by noisy representations of sound and speech. Furthermore, we will illustrate the development of a German prototype and will give an outlook on a current study that evaluates the efficacy of this training program in attenuating or even reversing cognitive decline in people with mild cognitive impairment or mild Alzheimer's disease.

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