Alexithymia in people with subjective cognitive decline, mild cognitive impairment, and mild Alzheimer's disease

The role of cognitive flexibility on higher level executive functions in mild cognitive impairment and healthy older adults

BACKGROUND

Mild Cognitive Impairment (MCI) is a preclinical condition between healthy and pathological aging, which is characterized by impairments in executive functions (EFs), including cognitive flexibility. According to Diamond's model, cognitive flexibility is a core executive function, along with working memory and inhibition, but it requires the development of these last EFs to reach its full potential. In this model, planning and fluid intelligence are considered higher-level EFs. Given their central role in enabling individuals to adapt their daily life behavior efficiently, the goal is to gain valuable insight into the functionality of cognitive flexibility in a preclinical form of cognitive decline. This study aims to investigate the role of cognitive flexibility and its components, set-shifting and switching, in MCI. The hypotheses are as follows: (I) healthy participants are expected to perform better than those with MCI on cognitive flexibility and higher-level EFs tasks, taking into account the mediating role of global cognitive functioning; (II) cognitive flexibility can predict performance on higher-level EFs (i.e., planning and fluid intelligence) tasks differently in healthy individuals and those diagnosed with MCI.

METHODS

Ninety participants were selected and divided into a healthy control group (N = 45; mean age 64.1 ± 6.80; 66.6% female) and an MCI group (N = 45; mean age 65.2 ± 8.14; 40% female). Cognitive flexibility, fluid intelligence, planning, and global cognitive functioning of all participants were assessed using standardized tasks.

RESULTS

Results indicated that individuals with MCI showed greater impairment in global cognitive functioning and EFs performance. Furthermore, the study confirms the predictive role of cognitive flexibility for higher EFs in individuals with MCI and only partially in healthy older adults.

Emotional and Neuropsychiatric Disorders Associated with Alzheimer's Disease

Alzheimer's disease is associated with impairments in emotional communication including comprehension and production of facial emotional expressions, comprehension of affective prosody, and alexithymia. It is also associated with disorders of emotional experience including mood disorders (depression and anxiety), agitation/aggression, and psychosis. Agitation/aggression and psychosis are particularly disruptive, are associated with earlier institutionalization, and pose a major challenge to institutional management. Treatment of disorders of emotional experience has been primarily pharmacologic (reviewed here in detail) and has relied heavily on antipsychotic medications despite the small effect sizes demonstrated in a large number of randomized controlled trials and the prevalence of serious side effects associated with these drugs. Recent studies suggest that treatment with pimavanserin, an antipsychotic without activity at dopamine receptors, may represent an important advance for treatment of psychotic manifestations, even as the drug appears to pose significant risk. Dextromethorphan/quinidine may represent an important advance in the treatment of agitation/aggression. There is also compelling evidence that sleep disorders, which are common among patients with Alzheimer's disease and are readily treatable, may potentiate psychotic manifestations and agitation/aggression, but further studies are needed.

Association of Anxiety Awareness with Risk Factors of Cognitive Decline in MCI

Studies demonstrate that anxiety is a risk factor for cognitive decline. However, there are also study findings regarding anxiety incidence among people with mild cognitive impairment (MCI), which mostly examined general anxiety evaluated by subjective questionnaires. This study aimed to compare subjective and objective anxiety (using autonomic measures) and anxiety as a general tendency and anxiety as a reaction to memory examination. Participants were 50 adults aged 59–82 years who were divided into two groups: MCI group and control group, according to their objective cognitive performance in the Rey Auditory Verbal Learning Test. Objective changes in the anxiety response were measured by skin conductivity in all tests and questionnaires. To evaluate subjective anxiety as a reaction to memory loss, a questionnaire on “state-anxiety” was used immediately after completing memory tests. Our main finding was that although both healthy and memory-impaired participants exhibited elevations in physiological arousal during the memory test, only healthy participants reported an enhanced state anxiety (p = 0.025). Our results suggest that people with MCI have impaired awareness of their emotional state.

Alexithymia in Alzheimer's Disease

Alexithymia is widely recognized as the inability to identify and express emotions. It is a construct which consists of four cognitive traits such as difficulty in identifying feelings, describing feelings to others, externally oriented thinking, and limited imaginative capacity. Several studies have linked alexithymia to cognitive functioning, observing greater alexithymia scores associated with poorer cognitive abilities. Despite Alzheimer's disease (AD) being a neurodegenerative pathology characterized by cognitive troubles from the early stages, associated to behavioral and emotional disturbances, very few investigations have studied the alexithymia in AD. These studies have shown that alexithymia scores-assessed with Toronto Alexithymia Scale (TAS)-were greater in AD patients than healthy participants. The objective of the study was to investigate if the alexithymia was present in patients with mild AD. We hypothesized that the AD group would show more alexithymia features than the control group. We evaluated 54 subjects, including 27 patients diagnosed with mild AD and 27 normal healthy controls, using the Shalling Sifneos Psychosomatic Scale (SSPS-R) and a neuropsychological test battery. Using non-parametric statistical analyses-Wilcoxon and Mann-Whitney U tests-we observed that the SSPS-R scores were similar in the AD and control groups. All participants showed SSPS-R scores below to 10 points, which means no-alexithymia. We did not find significant correlations between SSPS-R scores and cognitive variables in both groups (p > 0.22), but we observed a negative association between name abilities and alexithymia, but it does not reach to significance (p = 0.07). However, a significant correlation between SSPS-R score and mood state, assessed using Zerssen Rating Scale, was found in both groups (p = 0.01). Because we did not find a significant difference in the alexithymia assessment between both subject groups, pot hoc analyses were computed for each item of the SSPS-R. We made comparisons of alexithymic responses percentages in each SSPS-R item between AD and control groups, using Fisher's test. We observed that AD patients produced more alexithymic responses in some items of SSPS-R test than the control group, particularly about difficulties to find the words to describe feelings, as well as difficulties of imagination capacity and externally oriented thinking. The present results do not confirm our hypothesis and they do not support the results of previous studies revealing great alexithymia in AD.

Alexithymia is a non motor symptom of essential tremor regardless of the presence of depression and anxiety

OBJECTIVE

Essential tremor (ET) is one of the most common movement disorders. Aside from tremor, patients may exhibit other motor features as well as non-motor features, including neuropsychiatric symptoms. The cerebellum and cerebellar connections are thought to play a key role in the pathophysiology of ET. Cognitive and affective disturbances can occur in the context of cerebellar disease. Our aim was to study the prevalence and clinical correlates of alexithymia and its relationship to depression and anxiety in ET patients and control subjects (CS).

METHOD

We enrolled 100 ET patients and 100 age- and gender-matched CS. The Toronto Alexithymia Scale-20 (TAS-20), the Beck depression inventory-II and the Beck anxiety inventory were administered.

RESULTS

Alexithymia levels were significantly higher in ET patients than CS (respective mean TAS-20 scores = 50.63 ± 9.79 vs. 44.05 ± 12.51, p < 0.001).  There were robust associations between alexithymia, depressive symptoms, and anxiety but, after excluding the ET patients and the CS who had moderate or severe depression or who had moderate or severe anxiety, the total alexithymia score remained significantly higher in the ET than the CS group (46.78 ± 9.19 vs. 41.18 ± 11.79, p ≤ 0.01).

CONCLUSION

This study suggests that prevalence of alexithymia is significantly higher in ET patients. Alexithymia might be another non-motor neuropsychiatric symptom of the disease.  Further studies are needed to confirm and expand upon our findings.

Neuropsychiatric Symptoms and Risk Factors in Mild Cognitive Impairment: A Cohort Investigation of Elderly Patients

BACKGROUND

Neuropsychiatric symptoms (NPS) have been shown to affect the progression and development of Alzheimer's disease (AD) in the elderly. However, the published data are still controversial and limited in large cohort-based NPS study.

AIM

To explore the potential relationship between NPS and mild cognitive impairment (MCI) among the elderly of Chinese community.

METHODS

A total of 465 Chinese community-dwelling elderly (age ≥ 60 years) with mild cognitive impairment (MCI) were recruited into this investigation. At baseline, enrolled participants were assessed for Clinical Dementia Rating (CDR), mini-psychiatric examination. They were also subjected to categorical language fluency test, list learning and delayed recall. We assessed the NPS severity by Neuropsychological Inventory (NPI). The global cognitive status (GCS) of the participants at the end of the 3-year study period were measured with the CDR.

RESULTS

Approximately 41.6% of subjects had 1 or more NPS (total NPI score ≥ 1) at baseline. The most common NPSs were nocturnal behavior (20.8%), depression (17.3%), apathy (12.7%) and anxiety (13.2%). At the end of 3-year follow-up, 26.9% of baseline depressed patients developed AD, while 15.2% of baseline non-depressed patients developed AD (χ2 = 4.86, P=0. 04). Abnormal motor behavior was significantly correlated with cognitive deterioration as well (χ2 = 5.75, P=0. 03). Logistic regression analysis revealed that depression was considered as a risk factor for AD progression at baseline (95% CI: 1.12-5.67, OR=2.37, P=0.03).

CONCLUSIONS

Depression may be an independent factor representing early neurodegeneration in elder patients with MCI. Further studies are warranted to assess whether effective management of NPS promotes the cognitive functions.

An Initial Study of Alexithymia and Its Relationship With Cognitive Abilities Among Mild Cognitive Impairment, Mild Alzheimer's Disease, and Healthy Volunteers

The present study examined the degree to which alexithymia is greater in mild Alzheimer's disease (AD) and mild cognitive impairment (MCI) relative to healthy volunteers (healthy comparison [HC]), and investigated relationships between alexithymia and cognition. Eighty-five participants (MCI = 30, AD = 21, HC = 34) underwent a comprehensive neuropsychological examination and completed the 20-item Toronto Alexithymia Scale (TAS-20). Relative to HC, MCI and AD reported greater alexithymia total scores and higher scores on the TAS factor difficulty in identifying feelings (DIF). The remaining two factors, difficulty in describing feelings (DDF) and externally oriented thinking showed no significant group differences. In MCI, TAS-20 and DIF were negatively correlated with working and long-term verbal memory. In AD, TAS-20 was negatively correlated with general cognition, attention, memory, and visual spatial constructive and executive abilities. Also in AD, DIF was negatively correlated with general cognition, memory, and executive abilities. The correlation between DIF and long-term verbal memory in both MCI and AD suggests a potential common mechanism for alexithymia in these neurocognitive disorders. Declines in verbal memory may hinder a patient's ability to recall an association between a given sensation and the episodic experience of that sensation, thus leading to difficulty identifying feelings, as measured by the DIF factor of the TAS-20.