The relation between depressive symptoms and semantic memory in amnestic mild cognitive impairment and in late-life depression

Determinants of semantic and episodic memory decline among older adults in Ghana: Evidence from the WHO study on global AGEing and adult health Ghana wave 2

Objective

Determined factors associated with semantic (SM) and episodic memory (EM) among older adults aged 50 years and older in Ghana.

Methods

Data from WHO Study on Global AGEing and Adult Health (SAGE) Ghana Wave 2 was used for this study. Semantic memory (SM) and Episodic memory (EM) were the main study outcomes separately. The study employed Nested Ordinary Least Square regression analysis by sequentially adding 6 blocks of variables and comparison tests between the nested models.

Results

The study involved 3575 adult Ghanaians aged 50 years and older with a mean ± standard deviation of 62.6 ± 18.4 years. The overall mean ± SD of EM and SM were 5.86 ± 2.51 and 11.69 ± 8.59 respectively. Overall, analysis from block 6 showed a significant variation in SM by approximately 16.9%(ΔR2 = 1.17%) where increasing age, never married (β = -1.55; 95% CI = -2.41-0.69), being resident in Greater Accra (regional disparity) (β = -3.45; 95% CI = -4.73-2.20), underweight (β = -0.81;95% CI = -1.34-0.27), and moderate self-rated health (SRH) (β = -0.98; 95% CI = -1.52-0.45) significantly decreased SM. Similarly, increasing age, separated/divorced (β = -0.22; 95% CI = -0.35-0.87), being resident in Greater Accra (β = -0.53; 95% CI = -0.80-0.26), and moderate SRH (β = -0.20; 95% CI = -0.36--0.04) significantly decrease EM with an overall significant variation of approximately 22.9%(ΔR2 = 2.7%).

Conclusions

Increasing age, sex, marital status, regional disparity, and poor SRH significantly decreased both Semantic memory and Episodic memory. Higher educational attainment and life satisfaction significantly influenced SM and EM. These provide pointers to important socio-demographic determinants of SM and EM with implications for the implementation of the Ghana national ageing policy 2010, 'ageing with security and dignity', and as a key consideration for healthy ageing towards 2030.

The role of semantic assessment in the differential diagnosis between late-life depression and Alzheimer's disease or amnestic mild cognitive impairment: systematic review and meta-analysis

OBJECT

The cognitive complaints encountered in late-life depression (LLD) make it difficult to distinguish from amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD) based on an analysis of neurocognitive disorders. The hypothesis of the early impairment of semantic memory in AD and aMCI is considered a potential differential cognitive clue, but the absence of this impairment has not yet been confirmed in  LLD.

METHOD

Based on the PRISMA method, we systematically seek neuropsychological assessments of individuals with LLD, the present study included 31 studies representing 3291 controls and 2820 people with LLD. Wherever possible, studies that tested simultaneously groups with LLD, AD (or aMCI) were also included. The results of the group of neuropsychological tasks relying on semantic memory were analyzed in two groups of tasks with high- or low-executive demand. The mean average effect of LLD was calculated and compared to the incremental effect of aMCI or AD on the scores. Linear regressions including education, age, and severity and type of depression were run to seek their power of prediction for the mean average effects.

RESULTS

LLD has a medium effect on scores at semantic and phonemic fluency and naming and a small average effect on the low-executive demand tasks. Differences in education is a predictor of the effect of LLD on phonemic fluency and naming but not on semantic fluency or on low-executive demand tasks. Except for semantic fluency, aMCI did not demonstrate an incremental effect on the scores compared to LLD, while AD did, for all the tasks except phonemic fluency.

CONCLUSION

Assessment of semantic memory can be a discriminating clue for the distinction between depression and Alzheimer's disease but some methodological variables are highly influential to the scores, especially education. However, high-executive semantic tasks alone do not allow us to clearly distinguish LLD from AD or aMCI, as both pathologies seem to have a largely dialectical influential relationship, but low-executive semantic tasks appear as more sensible to this pathological distinction.

Depressive symptoms may be associated with semantic memory decline in elderly adults

Depressive symptoms are associated with a decline of episodic memory, but the relationship with semantic memory remains unclear.

Evaluating the Real-World Representativeness of Participants with Mild Cognitive Impairment in Canadian Research Protocols: a Comparison of the Characteristics of a Memory Clinic Patients and Research Samples

Background

Studies of mild cognitive impairment (MCI) employ rigorous eligibility criteria, resulting in sampling that may not be representative of the broader clinical population.

Objective

To compare the characteristics of MCI patients in a Calgary memory clinic to those of MCI participants in published Canadian studies.

Methods

Clinic participants included 555 MCI patients from the PROspective Registry of Persons with Memory SyMPToms (PROMPT) registry in Calgary. Research participants included 4,981 individuals with MCI pooled from a systematic literature review of 112 original, English-language peer-reviewed Canadian studies. Both samples were compared on baseline sociodemographic variables, medical and psychiatric comorbidities, and cognitive performance for MCI due to Alzheimer’s disease and Parkinson’s disease.

Results

Overall, clinic patients tended to be younger, more often male, and more educated than research participants. Psychiatric disorders, traumatic brain injury, and sensory impairment were commonplace in PROMPT (up to 83% affected) but > 80% studies in the systematic review excluded these conditions. PROMPT patients also performed worse on global cognition measures than did research participants.

Conclusion

Stringent eligibility criteria in Canadian research studies excluded a considerable subset of MCI patients with comorbid medical or psychiatric conditions. This exclusion may contribute to differences in cognitive performance and outcomes compared to real-world clinical samples.

A Meta-Analysis of Semantic Memory in Mild Cognitive Impairment

Accumulating evidence over the past decade suggests that semantic deficits represent a consistent feature of Mild Cognitive Impairment (MCI). A meta-analysis was performed to examine if semantic deficits are consistently found in patients with MCI. Studies meeting all inclusion criteria were selected for the current meta-analysis. An effect size and a weight were calculated for each study. A random effect model was performed to assess the overall difference in semantic performances between MCI patients and healthy subjects. 22 studies (476 healthy participants, 476 MCI patients, mean Mini Mental Status Examination of the MCI patients: 27.05 ± 0.58) were included in the meta-analysis. Results indicate that MCI patients systematically performed significantly worse than healthy matched controls in terms of overall semantic performance (mean effect size of 1.02; 95% CI [0.80; 1.24]). Semantic deficits are a key feature of MCI. Semantic tests should be incorporated in routine clinical assessments.

An Exploratory Study of Pathways from White Matter Hyperintensities to Cognitive Impairment through Depressive Symptoms Using Structural Equation Modeling: A Cross Sectional Study in Patients with Dementia

OBJECTIVE

The aim of this study was to model the relationships among white matter hyperintensities (WMHs), depressive symptoms, and cognitive function and to examine the mediating effect of depressive symptoms on the relationship between WMHs and cognitive impairment.

METHODS

We performed structural equation modeling using cross-sectional data from 1158 patients from the Clinical Research for Dementia of South Korea (CREDOS) registry who were diagnosed with mild-to-moderate dementia. Periventricular white matter hyperintensities (PWMHs) and deep white matter hyperintensities (DWMHs) were obtained separately on the protocol of magnetic resonance imaging (MRI). Depression and cognitive function were assessed using the Korean Form of the Geriatric Depression Scale (KGDS) and the Seoul Neuropsychological Screening Battery (SNSB), respectively.

RESULTS

The model that best reflected the relationships among the variables was the model in which DWMHs affected cognitive function directly and indirectly through the depressive symptoms; on the other hand, PWMHs only directly affected cognitive function.

CONCLUSIONS

This study presents the mediation model including the developmental pathway from DWMHs to cognitive impairment through depressive symptoms and suggests that the two types of WMHs may affect cognitive impairment through different pathways.

Determining the effects of LLD and MCI on brain decline according to machine learning and a structural covariance network analysis

BACKGROUND

Late-life depression (LLD) and mild cognitive impairment (MCI) are risk factors for Alzheimer disease (AD). However, the interactive effect between LLD and MCI in the progression to AD remains unknown. The purpose of this research is to clarify whether this interaction exists and determined the characteristics of the structural change patterns in LLD and MCI.

METHOD

To address this question, a total 225 participants (91 with intact cognitive function (IC), 34 with MCI, 35 with LLD-IC, 47 with LLD-MCI and 18 with AD) were recruited for the current study and their T1 scanning were acquired. Machine learning was applied to estimate the brain's age gap according to grey matter information (thickness and volume was calculated based on the Human Connectome Project Multi-Modal Parcellation version 1.0 and the Desikan atlas). A structural covariance network (SCN) was constructed based on grey matter volume. Rich-club analysis, global network properties and the Jaccard distance were utilized to describe the topological features in each cohort. Their cognitive functions (executive function, processing speed and memory) were evaluated by a full-scale battery of neuropsychological tests.

RESULT

The interactive effect between LLD and MCI was detected through the brain age gap. The estimated age was positively correlated with processing speed and memory in LLD and non-LLD subjects. In the SCN analysis, the rich-club coefficient and global network properties were disrupted in the MCI group, but remained normal in the LLD-IC, LLD-MCI and AD groups. There was a significant discrepancy in brain structural change patterns between the AD and other cohorts by the Jaccard distance.

CONCLUSION

The application of machine learning reflects that synergies between LLD and MCI could increase the risk of developing AD. According to the SCN, the structural coordination was disrupted in MCI and was kept normal in the other cohorts, while the discrepancies in brain structural change patterns appeared in AD. Overall, the brain age gap could be a potential predictor of AD, and the Jaccard distance has the potential to be a new type of SCN analysis indicator.

Depression, Anxiety, and Apathy in Mild Cognitive Impairment: Current Perspectives

Objective: Mild cognitive impairment (MCI) is an important risk state for dementia, particularly Alzheimer's disease (AD). Depression, anxiety, and apathy are commonly observed neuropsychiatric features in MCI, which have been linked to cognitive and functional decline in daily activities, as well as disease progression. Accordingly, the study's objective is to review the prevalence, neuropsychological characteristics, and conversion rates to dementia between MCI patients with and without depression, anxiety, and apathy. Methods: A PubMed search and critical review were performed relating to studies of MCI, depression, anxiety, and apathy. Results: MCI patients have a high prevalence of depression/anxiety/apathy; furthermore, patients with MCI and concomitant depression/anxiety/apathy have more pronounced cognitive deficits and progress more often to dementia than MCI patients without depression/anxiety/apathy. Conclusions and Implications: Depression, anxiety, and apathy are common in MCI and represent possible risk factors for cognitive decline and progression to dementia. Further studies are needed to better understand the role and neurobiology of depression, anxiety, and apathy in MCI.

Characteristics of Cognitive Deficit in Amnestic Mild Cognitive Impairment With Subthreshold Depression

It is widely recognized that depression may precipitate the incidence of dementia in the elderly individuals and individuals with amnestic mild cognitive impairment (aMCI) in particular. However, the association between subthreshold depression (SD) and cognitive deficits in patients with aMCI remains unclear. To address this, we collected demographic information and conducted a battery of neuropsychological cognitive assessments in 33 aMCI participants with SD (aMCI/SD+), 33 nondepressed aMCI participants (aMCI/SD-), and 53 normal controls (NC). Both aMCI groups showed significantly poorer performance in most cognitive domains relative to the NC group (ie, memory, language, processing speed, and executive function). Notably, the aMCI/SD+ group showed significantly poorer attention/working memory compared with the aMCI/SD- group. Multiple linear regression analyses revealed a significant negative association between the severity of depressive symptoms and attention/working memory capacity (β = - .024, P = .024), accounting for 8.28% of the variations in this cognitive domain. All statistical analyses were adjusted by age, sex, and years of education. A logistic regression model had an accuracy of 72.4% in discriminating between the aMCI/SD+ and aMCI/SD- groups based on individual cognitive profiles over 6 domains. Our findings indicate that patients with aMCI with and without SD have distinct patterns of cognitive impairment. This finding may facilitate the diagnosis and treatment of SD in patients with aMCI.

Early Life Trauma Predicts Affective Phenomenology and the Effects are Partly Mediated by Staging Coupled with Lowered Lipid-Associated Antioxidant Defences

Background Early life trauma (ELT) may drive mood disorder phenomenology, nitro-oxidative pathways and impairments in semantic memory. There are no data regarding the impact of ELT on affective phenomenology and whether these pathways are mediated by staging or lowered lipid-associated antioxidant defences. Methods This study examined healthy controls (n=54) and patients with affective disorders including major depression, bipolar disorder and anxiety disorders (n=118). ELT was assessed using the Child Trauma Questionnaire. In addition, we measured affective phenomenology and assayed advanced oxidation protein products; malondialdehyde, paraoxonase 1 (CMPAase) activity, high-sensitivity C-reactive protein (hsCRP), and high-density lipoprotein (HDL) cholesterol. Results ELT was associated into with increased risk for mood and comorbid anxiety disorders and a more severe phenomenology, including staging characteristics, depression and anxiety severity, suicidal behaviours, type of treatments, disabilities, body mass index, smoking behaviour and hsCRP, as well as lowered health-related quality of life, antioxidant defences and semantic memory. The number of mood episodes and CMPAase/HDL-cholesterol levels could be reliably combined into a new vulnerability staging-biomarker index, which mediates in part the effects of ELT on affective phenomenology and oxidative stress. Moreover, the effects of female sex on mood disorders and affective phenomenology are mediated by ELT. Discussion The cumulative effects of different ELT drive many aspects of affective phenomenology either directly or indirectly through effects of staging and/or lipid-associated antioxidant defences. The results show that children, especially girls, with ELT are at great risk to develop mood disorders and more severe phenotypes of affective disorders.

Diagnostic Value of Time-Constrained Naming Test in Mild Cognitive Impairment

BACKGROUND

Naming difficulties have recently garnered more interest in elderly individuals with mild cognitive impairment (MCI). We anticipate that naming tests with the consideration of response time can provide more informative and distinct neuropsychological profiles of individuals with MCI.

METHODS

Naming tests were administered to 76 elderly individuals with MCI and 149 healthy elderly (HE). We analyzed the impact of MCI on naming performance and occurrence of "delayed" response. We also validated the predictive power of naming tests with a time-constrained scoring system.

RESULTS

MCI participants performed poorer on the noun naming test than HE participants (p = 0.014). MCI was significantly associated with the occurrence of "delayed" response on the noun (odds ratio [OR] = 3.57; 95% confidence interval [CI] = 1.78-7.17) and verb naming tests (OR = 4.66; 95% CI = 2.07-10.46). The time-constrained naming scores were significantly better able to distinguish the MCI from the HE group than the conventional spontaneous naming score on both the noun (p < 0.001) and verb (p = 0.002) naming tests.

CONCLUSIONS

Our findings broaden the knowledge related to the naming ability in individuals with MCI, with respect to the response time. We also confirmed the validity of the naming tests by applying the "delayed" responses as supplementary assessments in the diagnosis of MCI.

The reduction of adult neurogenesis in depression impairs the retrieval of new as well as remote episodic memory

Major depressive disorder (MDD) is associated with an impairment of episodic memory, but the mechanisms underlying this deficit remain unclear. Animal models of MDD find impaired adult neurogenesis (AN) in the dentate gyrus (DG), and AN in DG has been suggested to play a critical role in reducing the interference between overlapping memories through pattern separation. Here, we study the effect of reduced AN in MDD on the accuracy of episodic memory using computational modeling. We focus on how memory is affected when periods with a normal rate of AN (asymptomatic states) alternate with periods with a low rate (depressive episodes), which has never been studied before. Also, unlike previous models of adult neurogenesis, which consider memories as static patterns, we model episodic memory as sequences of neural activity patterns. In our model, AN adds additional random components to the memory patterns, which results in the decorrelation of similar patterns. Consistent with previous studies, higher rates of AN lead to higher memory accuracy in our model, which implies that memories stored in the depressive state are impaired. Intriguingly, our model makes the novel prediction that memories stored in an earlier asymptomatic state are also impaired by a later depressive episode. This retrograde effect exacerbates with increased duration of the depressive episode. Finally, pattern separation at the sensory processing stage does not improve, but rather worsens, the accuracy of episodic memory retrieval, suggesting an explanation for why AN is found in brain areas serving memory rather than sensory function. In conclusion, while cognitive retrieval biases might contribute to episodic memory deficits in MDD, our model suggests a mechanistic explanation that affects all episodic memories, regardless of emotional relevance.

Semantic memory and depressive symptoms in patients with subjective cognitive decline, mild cognitive impairment, and Alzheimer's disease

BACKGROUND

Semantic memory may be impaired in clinically recognized states of cognitive impairment. We investigated the relationship between semantic memory and depressive symptoms (DS) in patients with cognitive impairment.

METHODS

323 cognitively healthy controls and 848 patients with subjective cognitive decline (SCD), mild cognitive impairment (MCI), and Alzheimer's disease (AD) dementia were included. Semantic knowledge for famous faces, world capitals, and word vocabulary was investigated.

RESULTS

Compared to healthy controls, we found a statistically significant difference of semantic knowledge in the MCI groups and the AD group, respectively. Results of the SCD group were mixed. However, two of the three semantic memory measures (world capitals and word vocabulary) showed a significant association with DS.

CONCLUSIONS

We found a difference in semantic memory performance in MCI and AD as well as an association with DS. Results suggest that the difference in semantic memory is due to a storage loss rather than to a retrieval problem.

Memory for emotional images differs according to the presence of depressive symptoms in individuals at risk for dementia

BACKGROUND

Studies of amnestic mild cognitive impairment (aMCI) and late-life depression (LLD) have examined the similarities and differences between these syndromes, but few have investigated how the cognitive profile of comorbid aMCI and subclinical depressive symptoms (aMCI/D+) may compare to that of aMCI or LLD. Memory biases for certain types of emotional information may distinguish these groups.

METHODS

A total of 35 aMCI, 23 aMCI/D+, 13 LLD, and 17 elderly controls (CONT) rated the valence (positive, negative, or neutral) of 30 pictures from the International Affective Picture System. Mean percent positive, negative, and neutral images recalled was compared within groups immediately and 30 minutes later.

RESULTS

Overall memory performance was comparable in aMCI and aMCI/D+, and both recalled fewer items than CONT and LLD. Group differences emerged when valence ratings were considered: at immediate and delayed recall, positive and negative pictures were generally better-remembered than neutral pictures by CONT, aMCI, and LLD, but valence was not associated with recall in aMCI/D+. Follow-up analyses suggested that the perceived intensity of stimuli may explain the emotional enhancement effect in CONT, aMCI, and LLD.

CONCLUSIONS

Results support previous research suggesting that the neuropsychological profile of aMCI/D+ is different from that of aMCI and LLD. Although depressed and non-depressed individuals with aMCI recall comparable quantities of information, the quality of the recalled information differs significantly. On theoretical grounds, this suggests the existence of distinct neurobiological or neurofunctional manifestations in both groups. Practically, these differences may guide the development of personalized emotion-focused encoding strategies in cognitive training programs.

Characteristics of neurocognitive functions in mild cognitive impairment with depression

BACKGROUND

Previous studies suggest that there is a strong association between depression and cognitive decline, and that concurrent depressive symptoms in MCI patients could contribute to a difference in neurocognitive characteristics compared to MCI patients without depression. The authors tried to compare neurocognitive functions between MCI patients with and without depression by analyzing the results of neuropsychological tests.

METHODS

Participants included 153 MCI patients. Based on the diagnosis of major depressive disorder, the participants were divided into two groups: depressed MCI (MCI/D+) versus non-depressed MCI (MCI/D-). The general cognitive and functional statuses of participants were evaluated. And a subset of various neuropsychological tests was presented to participants. Demographic and clinical data were analyzed using Student t-test or χ 2 test.

RESULTS

A total of 153 participants were divided into two groups: 94 MCI/D+ patients and 59 MCI/D- patients. Age, sex, and years of education were not significantly different between the two groups. There were no significant differences in general cognitive status between MCI/D+ and MCI/D- patients, but MCI/D+ participants showed significantly reduced performance in the six subtests (Contrasting Program, Go-no-go task, Fist-edge-palm task, Constructional Praxis, Memory Recall, TMT-A) compared with MCI/D- patients.

CONCLUSIONS

There were significantly greater deficits in neurocognitive functions including verbal memory, executive function, attention/processing speed, and visual memory in MCI/D+ participants compared to MCI/D-. Once the biological mechanism is identified, distinct approaches in treatment or prevention will be determined.

Characterizing cognitive performance in a large longitudinal study of aging with computerized semantic indices of verbal fluency

A computational approach for estimating several indices of performance on the animal category verbal fluency task was validated, and examined in a large longitudinal study of aging. The performance indices included the traditional verbal fluency score, size of semantic clusters, density of repeated words, as well as measures of semantic and lexical diversity. Change over time in these measures was modeled using mixed effects regression in several groups of participants, including those that remained cognitively normal throughout the study (CN) and those that were diagnosed with mild cognitive impairment (MCI) or Alzheimer's disease (AD) dementia at some point subsequent to the baseline visit. The results of the study show that, with the exception of mean cluster size, the indices showed significantly greater declines in the MCI and AD dementia groups as compared to CN participants. Examination of associations between the indices and cognitive domains of memory, attention and visuospatial functioning showed that the traditional verbal fluency scores were associated with declines in all three domains, whereas semantic and lexical diversity measures were associated with declines only in the visuospatial domain. Baseline repetition density was associated with declines in memory and visuospatial domains. Examination of lexical and semantic diversity measures in subgroups with high vs. low attention scores (but normal functioning in other domains) showed that the performance of individuals with low attention was influenced more by word frequency rather than strength of semantic relatedness between words. These findings suggest that various automatically semantic indices may be used to examine various aspects of cognitive performance affected by dementia.

Semantic memory impairment for biological and man-made objects in individuals with amnestic mild cognitive impairment or late-life depression

OBJECTIVE

Amnestic mild cognitive impairment (aMCI) and late-life depression (LLD) both increase the risk of developing Alzheimer disease (AD). Very little is known about the similarities and differences between these syndromes. The present study addresses this issue by examining the nature of semantic memory impairment (more precisely, object-based knowledge) in patients at risk of developing AD.

METHODS

Participants were 17 elderly patients with aMCI, 18 patients with aMCI plus depressive symptoms (aMCI/D+), 15 patients with LLD, and 29 healthy controls. All participants were aged 55 years or older and were administered a semantic battery designed to assess semantic knowledge for 16 biological and 16 man-made items.

RESULTS

Overall performance of aMCI/D+ participants was significantly worse than the 3 other groups, and performance for questions assessing knowledge for biological items was poorer than for questions relating to man-made items.

CONCLUSION

This study is the first to show that aMCI/D+ is associated with object-based semantic memory impairment. These results support the view that semantic deficits in aMCI are associated with concomitant depressive symptoms. However, depressive symptoms alone do not account exclusively for semantic impairment, since patients with LLD showed no semantic memory deficit.

Frequency and severity of semantic deficits in a consecutive memory clinic cohort

BACKGROUND/AIM

Semantic memory deficits have been shown in dementia and mild cognitive impairment (MCI) by group comparisons. The aim of this study is to investigate the frequency of impairments on tests with semantic content in patients with dementia, MCI (amnestic and non-amnestic) and affective disorders.

METHODS

A Famous faces test, Boston Naming Test and Category fluency were applied in 114 consecutive memory clinic patients and 95 healthy participants (all participants were 60 years old or older; dementia/MCI patients had Mini-Mental State Examination scores ≥20).

RESULTS

Fifty-three patients were classified with dementia, 36 with MCI (14 amnestic, 22 non-amnestic) and 25 with affective disorders. Dementia and MCI patients differed significantly from the control group on all tests. Patients with dementia and MCI had impairments in about 40% of the cases (on the most sensitive tests). However, patients with affective disorders also had mild impairments on tests tapping semantic memory (25% were impaired on the most sensitive tests). Impairments on the Famous faces test were more frequently found in dementia and MCI as compared to patients with affective disorders.

CONCLUSION

Short tests with semantic memory content are sensitive to changes in dementia and MCI, but impairments on such tests may also be found in other diseases, e.g. affective disorders.

Cognitive differences among depressed and non-depressed MCI participants: a project FRONTIER study

OBJECTIVE

Depression is the most commonly reported psychiatric symptom in patients with mild cognitive impairment (MCI). However, more research is needed examining the impact of depression on cognitive functioning in MCI patients. The purpose of this study was to examine differences in cognitive functioning in a sample of community- based, depressed, and non-depressed MCI patients.

METHODS

One hundred and five participants with MCI were included in this study. Participants were recruited from Project FRONTIER, a study of rural health. Depression was assessed via the Geriatric Depression Scale (GDS-30), and cognition was measured using the Repeatable Battery for the Assessment of Neuropsychological Status.

RESULTS

The results indicated that depressed MCI participants performed significantly worse than their non-depressed counterparts on several cognitive measures. MCI participants with depression scored significantly lower on immediate memory (t = 3.4, p < 0.01) and delayed memory (t = 2.8, p < 0.01) indices than their non-depressed counterparts.

CONCLUSIONS

The results of this study indicated that MCI participants with depression experienced greater deficits in cognitive functioning than their non-depressed counterparts. Depressed MCI participants exhibited greater deficits in both immediate and delayed memory. Thus, identifying and treating depression in individuals with MCI may improve memory and cognitive functioning.

Distinguishing Alzheimer's disease from other major forms of dementia

Alzheimer's disease (AD) is the most common and most studied cause of dementia. Significant advances have been made since the first set of clinical criteria for AD were put forth in 1984 that are now captured in the new criteria for AD published in 2011. Key features include recognition of a broad AD spectrum (from preclinical to mild cognitive impairment to AD dementia) and requirement of AD biomarkers for diagnosis. Correctly diagnosing dementia type is increasingly important in an era when potential disease-modifying agents are soon to be marketed. The typical AD dementia syndrome has at its core, an amnestic syndrome of the hippocampal type, followed by associated deficits in word-finding, spatial cognition, executive functions and neuropsychiatric changes. Atypical presentations of AD have also been identified that are presumed to have a different disease course. It can be difficult to distinguish between the various dementia syndromes given the overlap in many common clinical features across the dementias. The clinical difficulty in diagnosis may reflect the underlying pathology, as AD often co-occurs with other pathologies at autopsy, such as cerebrovascular disease or Lewy bodies. Neuropsychological evaluation has provided clinicians and researchers with profiles of cognitive strengths and weaknesses that help to define the dementias. There is yet no single behavioral marker that can reliably discriminate AD from the other dementias. The combined investigation of cognitive and neurobehavioral symptoms coupled with imaging markers could provide a more accurate approach for differentiating between AD and other major dementia syndromes in the future.