Mind-wandering is defined as a spontaneous shift of attention away from the external environment to inner thoughts. With mind-wandering being a ubiquitous phenomenon, there has been increasing interest in examining the role these spontaneous, and often unintentional, thought processes may have for metrics of cognitive and psychological health. However, much of this literature is mired with inconsistencies, potentially stemming from the use of variegated experimental methods and quantification of mind-wandering through different metrics. For example, mind-wandering has been investigated through endorsement of self-report probes embedded in tasks of sustained attention, with participants asking to endorse whether they were engaging in task-unrelated thoughts or task-related, but evaluative thoughts about the task (task-related interference). Other studies have instead focused on behavioral metrics of task performance, like omission and commission errors, the variability in response time (RTCV), and speeding or slowing prior to errors to quantify mind-wandering. In this study, employing a large sample of older adults, and implementing the novel technique of partial least squares regression, we examined the combined and simultaneous effect of different mind-wandering metrics in explaining variance in fluid cognition and psychological health in older adults.

One hundred and fifty older adults with normal cognition or mild cognitive impairment were administered a Go/No-Go Task (GNG) with embedded mind-wandering probes, the Conners CPT-3, the NIH Toolbox-Cognition Battery, and the WHO Quality of Life Assessment Brief Version at baseline in a clinical trial examining the impact of two mind-body interventions on aging. Based on previous research, the following variables were considered behavioral measures of mind-wandering: quantity of omission and commission errors, RTCV, pre-error speeding, and post-error slowing. Percentage of self-reported task-related interference (i.e. evaluating current performance) and task-unrelated thoughts were included as self-report measures of mind-wandering. These mind-wandering measures, along with demographic variables (age, sex, and education), were regressed using Partial Least Squares Regression to determine the impact of mind-wandering measures on fluid cognition (NIHT-CB) and perceived psychological well-being (WHOQOL-BBREF). Validation tests were completed to assess model fit.

A single latent factor explained 26% of the variance in fluid cognition (p=0.0001). Higher levels of age, errors of omission on both tasks, and task-related interference were all associated with worse fluid cognition, whereas task-unrelated thoughts were associated with better fluid cognition.

A two-factor latent model explained 12% of the variance in perceived psychological well-being (p=0.0004). Age and task-unrelated thoughts were positively associated with psychological well-being. In contrast, errors of omission on both tasks, response time variability on the CPT, and task-related interference were negatively associated with perceived psychological well-being.

Mind-wandering is associated with fluid cognition and perceived psychological well-being in older adults. Select behavioral measures were better than self-report measures at linking mind-wandering to fluid cognition and perceived psychological well-being. Interestingly task-unrelated thoughts, but not task-related interference, was positively associated with fluid cognition, supporting the cognitive resource-based account of mind-wandering. The result of our study provides novel insights into differential relationships between various metrics of mind-wandering and cognitive and psychological health.

The Weigl Colour-Form Sorting Test is a brief, widely used test of executive function. So far, it is unknown whether this test is specific to frontal lobe damage. Our aim was to investigate Weigl performance in patients with focal, unilateral, left or right, frontal, or non-frontal lesions.

We retrospectively analysed data from patients with focal, unilateral, left or right, frontal (n = 37), or non-frontal (n = 46) lesions who had completed the Weigl. Pass/failure (two correct solutions/less than two correct solutions) and errors were analysed.

A greater proportion of frontal patients failed the Weigl than non-frontal patients, which was highly significant (p < 0.001). In patients who failed the test, a significantly greater proportion of frontal patients provided the same solution twice. No significant differences in Weigl performance were found between patients with left versus right hemisphere lesions or left versus right frontal lesions. There was no significant correlation between performance on the Weigl and tests tapping fluid intelligence.

The Weigl is specific to frontal lobe lesions and not underpinned by fluid intelligence. Both pass/failure on this test and error types are informative. Hence, the Weigl is suitable for assessing frontal lobe dysfunction.

In schizophrenia, relative stability in the magnitude of cognitive deficits across age and illness duration is inconsistent with the evidence of accelerated deterioration in brain regions known to support these functions. These discrepant brain–cognition outcomes may be explained by variability in cognitive reserve (CR), which in neurological disorders has been shown to buffer against brain pathology and minimize its impact on cognitive or clinical indicators of illness.

Age-related change in fluid reasoning, working memory and frontal brain volume, area and thickness were mapped using regression analysis in 214 individuals with schizophrenia or schizoaffective disorder and 168 healthy controls. In patients, these changes were modelled as a function of CR.

Patients showed exaggerated age-related decline in brain structure, but not fluid reasoning compared to controls. In the patient group, no moderation of age-related brain structural change by CR was evident. However, age-related cognitive change was moderated by CR, such that only patients with low CR showed evidence of exaggerated fluid reasoning decline that paralleled the exaggerated age-related deterioration of underpinning brain structures seen in all patients.

In schizophrenia-spectrum illness, CR may negate ageing effects on fluid reasoning by buffering against pathologically exaggerated structural brain deterioration through some form of compensation. CR may represent an important modifier that could explain inconsistencies in brain structure – cognition outcomes in the extant literature.

Working memory (WM) performance is often decreased in older adults. Despite the growing popularity of WM trainings, underlying mechanisms are still poorly understood. Resistance to proactive interference (PI) constitutes a candidate process that contributes to WM performance and might influence training or transfer effects. Here, we investigated whether PI resistance can be enhanced in older adults using a WM training with specifically increased PI-demands. Further, we investigated whether potential effects of such a training were stable and entailed any transfer on non-trained tasks.

Healthy old adults (N = 25, 68.8 ± 5.5 years) trained with a recent-probes and an n-back task daily for two weeks. Two different training regimens (high vs. low PI-amount in the tasks) were applied as between-participants manipulation, to which participants were randomly assigned. Near transfer tasks included interference tasks; far transfer tasks assessed fluid intelligence (gF) or speed. Immediate transfer was assessed directly after training; a follow-up measurement was conducted after two months.

Both groups similarly improved in PI resistance in both training tasks. Thus, PI susceptibility was generally reduced in the two training groups and there was no difference between WM training with high versus low PI demands. Further, there was no differential near or far transfer on non-trained tasks, neither immediately after the training nor in the follow-up.

PI-demands in WM training tasks do not seem critical for enhancing WM performance or PI resistance in older adults. Instead, improved resistance to PI appears to be an unspecific side-effect of a WM training.

We recently demonstrated that decline in fluid intelligence is a substantial contributor to frontal deficits. For some classical ‘executive’ tasks, such as the Wisconsin Card Sorting Test (WCST) and Verbal Fluency, frontal deficits were entirely explained by fluid intelligence. However, on a second set of frontal tasks, deficits remained even after statistically controlling for this factor. These tasks included tests of theory of mind and multitasking. As frontal dysfunction is the most frequent cognitive deficit observed in early Parkinson's disease (PD), the present study aimed to determine the role of fluid intelligence in such deficits.

We assessed patients with PD (n=32) and control subjects (n=22) with the aforementioned frontal tests and with a test of fluid intelligence. Group performance was compared and fluid intelligence was introduced as a covariate to determine its role in frontal deficits shown by PD patients.

In line with our previous results, scores on the WCST and Verbal Fluency were closely linked to fluid intelligence. Significant patient–control differences were eliminated or at least substantially reduced once fluid intelligence was introduced as a covariate. However, for tasks of theory of mind and multitasking, deficits remained even after fluid intelligence was statistically controlled.

The present results suggest that clinical assessment of neuropsychological deficits in PD should include tests of fluid intelligence, together with one or more specific tasks that allow for the assessment of residual frontal deficits associated with theory of mind and multitasking.