Age-related alterations in inhibitory control investigated using the minimally delayed oculomotor response task

Are you more impulsive with age? Examining age, marital status, and gender on cognitive ageing

Understanding non-pathological cognitive aging processes remains a public health goal and research priority. Age-associated cognitive aging is a normal human process, however, individual differences may aid in the mitigation of cognitive aging. Assessing the role of certain protective factors (i.e., age, marital status, and gender) that influence age-related cognitive aging is imperative to slow down the progression of unwarranted cognitive aging. Participants aged over 18 (N = 123; 97 females and 26 males) recruited from Sydney, New South Wales, and Gold Coast, Queensland, completed an online neuropsychological test battery with computer-administered tasks, assessing impulsivity and working memory, which were entered as dependent variables. A 3(Age Group: 18-27 years; 28-61 years; 62+ years) x2(Marital Status: married; single) x2(Gender: male; female) Multivariate Analysis of Covariance (MANCOVA) design was used to examine the relationship between age, marital status, and gender (entered as independent variables) on cognitive aging. Participants' total scores from psychometrically sound measures assessing depressive symptomology, personal wellbeing, resilience, and social network engagement, were entered as covariates. No significant effects were found from the independent variables included in the MANCOVA. A significant covariate effect for resilience and depressive symptomology on impulsivity was found. A multiple regression analysis was performed on the significant covariates, and revealed increased resilience and depressive symptomology to significantly predict greater impulsivity.

Antisaccade error rates and gap effects in psychosis syndromes from bipolar-schizophrenia network for intermediate phenotypes 2 (B-SNIP2)

BACKGROUND

Antisaccade tasks can be used to index cognitive control processes, e.g. attention, behavioral inhibition, working memory, and goal maintenance in people with brain disorders. Though diagnoses of schizophrenia (SZ), schizoaffective (SAD), and bipolar I with psychosis (BDP) are typically considered to be distinct entities, previous work shows patterns of cognitive deficits differing in degree, rather than in kind, across these syndromes.

METHODS

Large samples of individuals with psychotic disorders were recruited through the Bipolar-Schizophrenia Network on Intermediate Phenotypes 2 (B-SNIP2) study. Anti- and pro-saccade task performances were evaluated in 189 people with SZ, 185 people with SAD, 96 people with BDP, and 279 healthy comparison participants. Logistic functions were fitted to each group's antisaccade speed-performance tradeoff patterns.

RESULTS

Psychosis groups had higher antisaccade error rates than the healthy group, with SZ and SAD participants committing 2 times as many errors, and BDP participants committing 1.5 times as many errors. Latencies on correctly performed antisaccade trials in SZ and SAD were longer than in healthy participants, although error trial latencies were preserved. Parameters of speed-performance tradeoff functions indicated that compared to the healthy group, SZ and SAD groups had optimal performance characterized by more errors, as well as less benefit from prolonged response latencies. Prosaccade metrics did not differ between groups.

CONCLUSIONS

With basic prosaccade mechanisms intact, the higher speed-performance tradeoff cost for antisaccade performance in psychosis cases indicates a deficit that is specific to the higher-order cognitive aspects of saccade generation.

Confirmation of age-related alterations in inhibitory control using a modified minimally delayed oculomotor response (MDOR) task

Considerable effort has been made to measure and understand the effects of ageing on inhibitory control using a range of behavioural tasks. In the minimally delayed oculomotor response (MDOR) task, participants are presented with a simple visual target step with variable target display duration (TDD), and instructed to saccade to the target not when it appears (a prosaccade response), but when it disappears (i.e., on target offset). Using this task, we recently found higher error rates and longer latencies for correct responses in older compared to younger participants. Here we have used a modified MDOR task, in which participants were presented with static placeholders identifying potential target positions (increasing spatial information), and three TDDs rather than two (reducing temporal predictability). We found that the yield of analysable trials was generally higher with this modified task and in 28 older (mean ± SD age: 65 ± 7 y) and 25 younger (26 ± 7 y) participants the total overall error rate was again higher in the older group (30 ± 18% vs. 16 ± 11%). An analysis of the temporal distribution of responses demonstrated a pronounced peak in error production around 150 ms (young) or 200 ms (old) after target onset. When we recalculated the error rate focusing on these errors, it was again significantly higher in the older group. The latency of correct responses (to offsets) was significantly increased in the older group, although much of this increase was accounted for by expected age-related visuomotor slowing. However, both latency and distribution data suggested that while older participants could generate increased levels of inhibition, they could not maintain these levels as efficiently as the younger participants. In 24 participants (15 old, 9 young) who completed both versions of the MDOR task, neither latency nor error rates differed significantly between versions. These results confirm an inhibitory control deficit in healthy older participants, and suggest that the dynamics of inhibitory control are also affected by ageing. The modified MDOR task yields more data while not altering basic performance parameters.