Non-invasive Brain Stimulation: Probing Intracortical Circuits and Improving Cognition in the Aging Brain.

The impact of cognitive aging on brain function and structure is complex, and the relationship between aging-related structural changes and cognitive function are not fully understood. Physiological and pathological changes to the aging brain are highly variable, making it difficult to estimate a cognitive trajectory with which to monitor the conversion to cognitive decline. Beyond the information on the structural and functional consequences of cognitive aging gained from brain imaging and neuropsychological studies, non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) can enable stimulation of the human brain , offering useful insights into the functional integrity of intracortical circuits using electrophysiology and neuromodulation.

The effects of medication use in transcranial direct current stimulation: A brief review.

Background: There has been increased interest in the potential use of transcranial direct current stimulation (tDCS) as treatment for multiple conditions including depression, pain, and cognitive impairment. However, few studies account for the possible influence of comorbid medications when conducting tDCS research.

Objective/hypothesis: This literature review was conducted to examine what is currently known about the impact of medications on tDCS, provide recommendations for future research practices, and highlight areas where more research is needed.

Precuneus abnormalities in middle-aged to older adults with depressive symptoms: An analysis of BDI-II symptom dimensions.

We recently reported age-related increases in left precuneus cortical thickness (CT) in older adults with elevated total depressive symptoms. However, it is unclear whether abnormalities in precuneus surface area (SA) are also evident and whether specific symptom dimensions of depression moderated age effects on these measurements. Seventy-three adults completed the Beck Depression Inventory - 2nd edition (BDI-II) and underwent structural neuroimaging.

Vertex-wise examination of depressive symptom dimensions and brain volumes in older adults.

Differences in brain volumes have commonly been reported in older adults with both subthreshold and major depression. Few studies have examined the association between specific symptom dimensions of depression and brain volumes. This study used vertex-wise analyses to examine the association between specific symptom dimensions of depression and brain volumes in older adults with subthreshold levels of depressive symptoms.

Transcranial Direct Current Stimulation Use in the Treatment of Neuropsychiatric Disorders: A Brief Review.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has grown in popularity over the past two decades as an alternative treatment option for various neuropsychiatric disorders. tDCS modulates cortical excitability through the application of a weak direct current to the scalp via electrodes placed over cortical regions of interest. It has been shown to be a promising and relatively safe treatment tool with few adverse events.

Depressive symptoms modify age effects on hippocampal subfields in older adults.

Aim: Major depression is associated with hippocampal volume changes, especially in late-life depression. These changes usually consist of volume reductions, but depression-related increases in hippocampal volume have also been reported. Subfield analysis has identified structural changes primarily in the cornu ammonis (CA) 1, CA2-3 and subiculum of the hippocampus in individuals with major depression; however, it is unclear whether lower levels of depressive symptoms are also associated volume reduction, or if depressive symptoms interact with age to impact hippocampal subfields.

Anxiety Modifies the Association between Fatigue and Verbal Fluency in Cognitively Normal Adults.

Objective: In the present study, we examined the association between self-reported fatigue and verbal fluency in a sample of healthy adults. Given the co-occurrence of anxiety and depressive symptoms with fatigue, we examined whether these affective dimensions would modify this association.

Method: Fifty-nine cognitively normal adults took part in the study.

Factors Influencing Clinical Correlates of Chronic Traumatic Encephalopathy (CTE): a Review.

Chronic traumatic encephalopathy (CTE) is a neuropathologically defined disease reportedly linked to a history of repetitive brain trauma. As such, retired collision sport athletes are likely at heightened risk for developing CTE. Researchers have described distinct pathological features of CTE as well a wide range of clinical symptom presentations, recently termed traumatic encephalopathy syndrome (TES).

Effects of body mass index and education on verbal and nonverbal memory.

We previously reported that higher education protects against executive dysfunction related to higher body mass index (BMI) in younger, but not older, adults. We now extend the previous analyses to verbal and nonverbal memory. Fifty-nine healthy, dementia-free community-dwelling adults ranging in age from 18 to 81 years completed the Hopkins Verbal Learning Test - Revised (HVLT-R) and the Brief Visuospatial Memory Test - Revised (BVMT-R).

Age Differences in Prefrontal Surface Area and Thickness in Middle Aged to Older Adults.

Age is associated with reductions in surface area and cortical thickness, particularly in prefrontal regions. There is also evidence of greater thickness in some regions at older ages. Non-linear age effects in some studies suggest that age may continue to impact brain structure in later decades of life, but relatively few studies have examined the impact of age on brain structure within middle-aged to older adults.

Depressive symptom severity is associated with increased cortical thickness in older adults.

Objective: Structural neuroimaging studies in older adults have consistently shown volume reductions in both major and subthreshold depression. Cortical thickness, another measure of brain structure, has not been well studied in this population. We examined cortical thickness in older adults across a range of depressive symptom (DS) severity.

Impact of Education on Memory Deficits in Subclinical Depression.

Elevated depressive symptoms are associated with cognitive deficits, while higher education protects against cognitive decline. This study was conducted to test if education level moderates the relationship between depressive symptoms and cognitive function. Seventy-three healthy, dementia-free adults aged 18-81 completed neuropsychological tests, as well as depression and anxiety questionnaires.

Unique and interactive effect of anxiety and depressive symptoms on cognitive and brain function in young and older adults.

Objective: Depression and anxiety and are associated with cognitive deficits and brain changes, especially in older adults. Despite the frequent co-occurrence of these conditions, cognitive neuroscience studies examining comorbid depression and anxiety are limited. The goal of the present study was to examine the unique and combined effect of depressive and anxiety symptoms on cognitive and brain functioning in young and older adults.

Impact of aerobic exercise on neurobehavioral outcomes.

Numerous studies have examined the relationship between physical activity and cognitive function, demonstrating that greater physical activity is associated with lower incidence of cognitive impairment in later life. Due to an increasingly large number of older adults at risk for cognitive impairment, the relationship between physical activity and cognition has garnered increasing public health relevance and multiple randomized trials have demonstrated that exercise interventions among sedentary adults improve cognitive performance in multiple domains of function. This article will examine the relationship between physical activity and cognitive function by reviewing several different areas of literature, including the prevalence of cognitive impairment, assessment methods, observational studies examining physical activity and cognition, and intervention studies.