Cognitive functioning throughout the treatment history of clinical late-life depression

Does depression in mid-life predispose to greater cognitive decline in later life in the Whitehall II cohort?

BACKGROUND

Later-life depression appears to have different symptomatology and possibly underlying pathology to younger adults. Depression is linked to dementia but whether it is a risk factor or an early sign of dementia remains unclear. Neuroinflammation is increasingly recognised in both conditions.

AIMS

To investigate the link between depression, inflammation and dementia. We hypothesised that recurrent depression increases the rate of cognitive decline in older adults and that this effect is modified by anti-inflammatory medication.

METHODS

We used data from Whitehall II including cognitive test results and reliable measures to assess depression. Depression was defined as a self-reported diagnosis or a score of ≥20 on the CESD. The presence/absence of inflammatory illness was assessed using a standardised list of inflammatory conditions. Individuals with dementia, chronic neurological and psychotic conditions were excluded. Logistic and linear regression was used to examine the effect of depression on cognitive test performance and the effect of chronic inflammation.

LIMITATIONS

Lack of clinical diagnoses of depression.

RESULTS

There were 1063 individuals with and 2572 without depression. Depression did not affect deterioration in episodic memory, verbal fluency or the AH4 test at 15-year follow up. We found no evidence of an effect of anti-inflammatory medication. Depressed individuals had worse cross-sectional performance on the Mill Hill test and tests of abstract reasoning and verbal fluency at both baseline and 15-year follow-up.

CONCLUSIONS

Using a UK based study with a long follow-up interval we have shown that depression in individuals aged >50 is not associated with increased cognitive decline.

Between-person and within-person effects in the temporal relationship between depressive symptoms and cognitive function

BACKGROUND

e aimed to disentangle within-person and between-person effects in the temporal relationship between depressive symptoms and cognitive function.

METHODS

We performed a prospective population-based cohort study on participants of the Survey of Health, Ageing and Retirement in Europe. Cognitive function was assessed by tests on verbal fluency, immediate recall and delayed recall. Depressive symptoms were measured with EURO-D scale. To determine the temporal order of the association between cognitive function and depressive symptoms, we employed the fully saturated cross-lagged panel model (between-person effects), and random intercept cross-lagged panel model (within-person effects).

RESULTS

In 59,311 participants (mean age 65, ranging 46-100), between-person effects showed a bi-directional relationship that could be seen in three stages: First, the effect of cognitive function on depressive symptoms was initially slightly stronger than vice versa. Second, the effect of depressive symptoms on cognitive function became stronger during the follow-up. Third, all effects were small and no direction dominated. Within-person effects, however, revealed a dominant effect from depressive symptoms on cognitive function. Some effects from cognitive function on depressive symptoms were apparent only in older adults, in particular men. All effects were small and strongest for individuals aged 65 years and above.

LIMITATIONS

The sample is healthier than general population and thus not fully representative. A comprehensive cognitive battery was not available.

CONCLUSIONS

Long-term relationship between depressive symptoms and cognitive function is bi-directional. However, to achieve improvement in an individual in the short-term, the focus should be on decreasing depressive symptoms to improve cognitive function.

Depression and memory function - evidence from cross-lagged panel models with unit fixed effects in ELSA and HRS

BACKGROUND

Individuals with depression are often found to perform worse on cognitive tests and to have an increased risk of dementia. The causes and the direction of these associations are however not well understood. We looked at two specific hypotheses, the aetiological risk factor hypothesis and the reverse causality hypothesis.

METHOD

We analysed observational data from two cohorts, English Longitudinal Study of Ageing (ELSA) and Health and Retirement Study (HRS), using cross-lagged panel models with unit fixed effects. Each model was run once with depression and repeated with cognition as the dependent variable and the other variable as the main explanatory variable. All models were estimated separately for contemporaneous effects and lagged effects up to 8 years in the past. We contrasted the results with models making the random effects assumption.

RESULTS

Evidence from the fixed effects models is mixed. We find no evidence for the reverse causality hypothesis in ELSA and HRS. While there is no evidence for the aetiological risk factors hypothesis in ELSA, results from HRS indicate some effects.

CONCLUSION

Our findings suggest that current levels of cognitive function do not influence future levels of depression. Results in HRS provide some evidence that current levels of depressive symptoms influence future cognition.

Risk Assessment During Longitudinal Progression of Cognition in Older Adults: A Community-based Bayesian Networks Model

BACKGROUND

Cognitive dysfunction, particularly in Alzheimer's disease (AD), seriously affects the health and quality of life of older adults. Early detection can prevent and slow cognitive decline.

OBJECTIVE

This study aimed at evaluating the role of socio-demographic variables, lifestyle, and physical characteristics in cognitive decline during AD progression and analyzing the probable causes and predicting stages of the disease.

METHODS

By analyzing data of 301 subjects comprising normal elderly and patients with mild cognitive impairment (MCI) or AD from six communities in Taiyuan, China, we identified the influencing factors during AD progression by a Logistic Regression model (LR) and then assessed the associations between variables and cognition using a Bayesian Networks (BNs) model.

RESULTS

The LR revealed that age, sex, family status, education, income, character, depression, hypertension, disease history, physical exercise, reading, drinking, and job status were significantly associated with cognitive decline. The BNs model revealed that hypertension, education, job status, and depression affected cognitive status directly, while character, exercise, sex, reading, income, and family status had intermediate effects. Furthermore, we predicted probable cognitive stages of AD and analyzed probable causes of these stages using a model of causal and diagnostic reasoning.

CONCLUSION

The BNs model lays the foundation for causal analysis and causal inference of cognitive dysfunction, and the prediction model of cognition in older adults may help the development of strategies to control modifiable risk factors for early intervention in AD.

Geriatric Depression and Cognitive Impairment-An Update

BACKGROUND

Depression and cognitive impairment often coexist in older adults. The relation between depression and cognitive impairment is complex. The objective of this article is to review recent literature on cognitive impairment in older adults with depression and provide clinicians an update.

METHODS

We searched PubMed, Google Scholar, Science Direct, and Psych Info for the articles published in the English language related to late-life depression (LLD)/geriatric depression and cognitive impairment. We considered original research articles, relevant systematic reviews, chapters, and important conceptual articles published in the last 9 years (2011-2019). We selected relevant articles for this narrative review.

CONCLUSION

The concept pseudodementia, indicating depression with cognitive impairment mimicking dementia, is now seen only as a historical concept. The current literature strongly agrees with fact that cognitive deficits often exist in LLD. The cognitive deficits in depression were initially seen as trait marker; however, some recent studies suggest that cognitive deficits persist even in the remission phase. There is heterogeneity among the studies in terms of the nature of the cognitive deficits, but higher number of studies reported impairment in attention and executive function. LLD with cognitive deficits is at a higher risk of progression to dementia. In older adults, depression with cognitive impairments requires a comprehensive evaluation. Electroencephalography, event-related potentials, fluorodeoxyglucose-positron emission tomography, amyloid positron emission tomography, and CSF amyloid will supplement clinical evaluation in differentiating functional depressive disorder with cognitive impairment from depression with an underlying degenerative condition.

The Effect of Cognitive Impairment on the Prognosis of Major Depressive Disorder

The study recruited 168 patients diagnosed with major depressive disorder (MDD). The nine-item Patient Health Questionnaire (PHQ-9) and Perceived Deficits Questionnaire for Depression (PDQ-D) were lower and the Digit Symbol Substitution Test (DSST) was higher in the community volunteers than those in MDD patients. Depression-related scores (17-item Hamilton Depression Rating Scale [HAMD-17], Clinical Global Impressions-Severity of Illness Scale [CGI-S], and PHQ-9), functioning-related scores (Sheehan Disability Scale [SDS]), and Work Efficiency and Activity Damage-Specific Health Problems questionnaire work productivity loss were decreased, and the quality of life-related scores (European Quality of life-5 Dimensions [EQ-5D] utility score) were increased in the MDD patients. PDQ-D was decreased and DSST was increased with the increase of follow-up time. Linear regression indicated that cognitive symptoms (PDQ-D and DSST) improved more slowly than depressive symptoms (PHQ-9). At baseline, PDQ-D was related with functioning (SDS and work productivity loss). PDQ-D and DSST were related with EQ-5D utility score. In addition, at month 6, PDQ-D was related with functioning (SDS and work productivity loss) and EQ-5D utility score. Cognitive impairment might be a risk for MDD and MDD-related changes in the functioning and quality of life.

Effects of between-person differences and within-person changes in symptoms of anxiety and depression on older age cognitive performance

BACKGROUND

Anxiety and depression are both important correlates of cognitive function. However, longitudinal studies investigating how they covary with cognition within the same individual are scarce. We aimed to simultaneously estimate associations of between-person differences and within-person variability in anxiety and depression with cognitive performance in a sample of non-demented older people.

METHODS

Participants in the Lothian Birth Cohort 1921 study, a population-based narrow-age sample (mean age at wave 1 = 79 years, n = 535), were examined on five occasions across 13 years. Anxiety and depression were measured with the Hospital Anxiety and Depression Scale (HADS) and cognitive performance was assessed with tests of reasoning, logical memory, and letter fluency. Data were analyzed using two-level linear mixed-effects models with within-person centering.

RESULTS

Divergent patterns were observed for anxiety and depression. For anxiety, between-person differences were more influential; people who scored higher on HADS anxiety relative to other same-aged individuals demonstrated poorer cognitive performance on average. For depression, on the other hand, time-varying within-person differences were more important; scoring higher than usual on HADS depression was associated with poorer cognitive performance relative to the average level for that participant. Adjusting for gender, childhood mental ability, emotional stability, and disease burden attenuated these associations.

CONCLUSIONS

The results from this study highlight the importance of addressing both between- and within-person effects of negative mood and suggest that anxiety and depression affect cognitive function in different ways. The current findings have implications for assessment and treatment of older age cognitive deficits.

The relationship between cognition and depressive symptoms, and factors modifying this association, in Alzheimer's disease: A multivariate multilevel model

OBJECTIVES

To examine whether there was a bidirectional association between cognition and depressive symptoms in Alzheimer's disease (AD), and to explore the role of socio-demographic factors and daily performance in this association.

METHODS

We conducted a longitudinal study of 104 community-dwelling patients with confirmed AD from Taiyuan, China. We assessed cognition and depressive symptoms (dependent variables) with the Montreal Cognitive Assessment (MoCA) and the Geriatric Depression Scale-30 (GDS-30), respectively. Socio-demographic information and daily performance were treated as explanatory variables. A multivariate multilevel model was built to investigate the interrelationship between patients' cognition and depression, as well as the effect of related factors on both outcomes.

RESULTS

MoCA scores were negatively correlated with GDS-30 both at the subject level (correlation coefficient r₃=-0.68, χ²=19.26, P<0.001) and time point level (r₂=-0.35, χ²=35.68, P<0.001) in patients with AD. Multivariate analysis showed several significant factors for cognitive function, including educational level, personality, hobbies, exercise, reading, aluminum utensil use, dietary restriction and hypertension (regression coefficients: 0.60, 0.52, 0.51, 0.48, 0.45, -0.48, 0.67, and -0.74, respectively). Significant factors for depressive symptoms included family status, employment before retirement, homemaking, reading, aluminum utensil use, dietary restriction, and hypertension (regression coefficients: 3.09, -1.33, -1.62, -1.31, 0.96, -1.15, and 1.14, respectively).

CONCLUSION

These findings indicated that cognition was negatively associated with depression in patients with AD, and both were influenced by reading, aluminum utensil use, dietary restriction, and hypertension. Considering patient factors may help to slow the progression of dementia.

Elucidating the link between the modifiable risk factors of Alzheimer's disease and neuroinflammation

Increased worldwide longevity through medical interventions, although beneficial, has allowed the age-related Alzheimer's disease (AD) to become an epidemic of the 21st century. AD pathology involves adverse activation of microglia, the immune cells of the brain and resulting chronic neuroinflammation. Certain diets, physical inactivity and Type 2 diabetes mellitus have been identified as the risk factors for developing AD, which may increase the risk of AD by neuroimmune mechanisms primarily through the overactivation of microglia. Thus, modifying these risk factors may represent an alternative therapeutic strategy for lowering the incidence of AD. We highlight the link between select modifiable risk factors and neuroimmune mechanisms, and demonstrate that by controlling microglial activation and neuroinflammation the prevalence of AD may be decreased.