P. M. Doraiswamy

Default mode network connectivity in stable vs progressive mild cognitive impairment

Objective: Dysfunction of the default mode network (DMN) has been identified in prior cross-sectional fMRI studies of Alzheimer disease (AD) and mild cognitive impairment (MCI); however, no studies have examined its utility in predicting future cognitive decline. Methods: fMRI scans during a face–name memory task were acquired from a cohort of 68 subjects (25 normal control, 31 MCI, and 12 AD). Subjects with MCI were followed for 2.4 years (±0.8) to determine progression to AD. Maps of DMN connectivity were compared with a template DMN map constructed from elderly normal controls to obtain goodness-of-fit (GOF) indices of DMN expression. Indices were compared between groups and correlated with cognitive decline. Results: GOF indices were highest in normal controls, intermediate in MCI, and lowest in AD (p < 0.0001). In a predictive model (that included baseline GOF indices, age, education, Mini-Mental State Examination score, and an index of DMN gray matter volume), the effect of GOF index on progression from MCI to dementia was significant. In MCI, baseline GOF indices were correlated with change from baseline in functional status (Clinical Dementia Rating–sum of boxes) (r = −0.40, p < 0.04). However, there was no additional predictive value for DMN connectivity when baseline delayed recall was included in the models. Conclusions: fMRI connectivity indices distinguish patients with MCI who undergo cognitive decline and conversion to AD from those who remain stable over a 2- to 3-year follow-up period. Our data support the notion of different functional brain connectivity endophenotypes for “early” vs “late” MCI, which are associated with different baseline memory scores and different rates of progression and conversion.

Posterior fossa abnormalities in major depression: a controlled magnetic resonance imaging study

High‐field magnetic resonance (MR) images were used to study posterior fossa morphology in 27 patients with major depression and 36 normal control subjects. Depressed patients demonstrated smaller brain stem and cerebellar vermis than controls. These differences were highly significant for the anterior cerebellar vermis and medulla. There was also a striking age‐related decline in midbrain size in depressed patients as well as in controls. Our results are consistent with several lines of evidence implicating a role for the cerebellar vermis in affective disorders and, in addition, provide the first MR documentation of the differential effects of aging on posterior fossa morphology in normal subjects compared with patients with major depression.

Effects of Donepezil on Cortical Activation in Mild Cognitive Impairment: A Pilot Double-Blind Placebo-Controlled Trial Using Functional MR Imaging

BACKGROUND AND PURPOSE: Cholinesterase-inhibitor therapy is approved for treatment of Alzheimer disease; however, application in patients with mild cognitive impairment (MCI) is still under active investigation. The purpose of this study was to determine the effect of such therapy on the neural substrates underlying memory processing in subjects with MCI by using functional MR imaging (fMRI). MATERIALS AND METHODS: Thirteen subjects with MCI (mean age, 68 ± 6.9 years) enrolled in a multicenter double-blind placebo-controlled trial testing the clinical efficacy of the cholinesterase-inhibitor, donepezil, were studied with fMRI at baseline and following 12 or 24 weeks of therapy (single-site pilot study). The cognitive paradigm was delayed-response visual memory for novel faces. Within-group 1-sample t tests were performed on the donepezil and placebo groups at baseline and at follow-up. A repeated-measures analysis of variance design was used to look for a Treatment Group × Time interaction showing a significant donepezil- but not placebo-related change in blood oxygen level–dependent response during the course of the study. RESULTS: At baseline, both groups showed multiple areas of activation, including the bilateral dorsolateral prefrontal cortex, fusiform gyrus, and anterior cingulate cortex. On follow-up, the placebo group demonstrated a decreased extent of dorsolateral prefrontal activation, whereas the donepezil group demonstrated an increased extent of activation in the ventrolateral prefrontal cortex. Interaction demonstrated significant donepezil- but not placebo-related change in the left inferior frontal gyrus. CONCLUSIONS: Despite the limitations inherent to a pilot study of a small sample, our results point to specific cortical substrates underlying the actions of donepezil, which can be tested in future studies.

Dissecting the gene dose-effects of the APOE ε4 and ε2 alleles on hippocampal volumes in aging and Alzheimer's disease.

Objective To investigate whether there is a specific dose-dependent effect of the Apolipoprotein E (APOE) ε4 and ε2 alleles on hippocampal volume, across the cognitive spectrum, from normal aging to Alzheimer’s Disease (AD). Materials and Methods We analyzed MR and genetic data on 662 patients from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database–198 cognitively normal controls (CN), 321 mild-cognitive impairment (MCI) subjects, and 143 AD subjects–looking for dose-dependent effects of the ε4 and ε2 alleles on hippocampal volumes. Volumes were measured using a fully-automated algorithm applied to high resolution T1-weighted MR images. Statistical analysis consisted of a multivariate regression with repeated-measures model. Results There was a dose-dependent effect of the ε4 allele on hippocampal volume in AD (p = 0.04) and MCI (p = 0.02)–in both cases, each allele accounted for loss of >150 mm3 (approximately 4%) of hippocampal volume below the mean volume for AD and MCI subjects with no such alleles (Cohen’s d = −0.16 and −0.19 for AD and MCI, respectively). There was also a dose-dependent, main effect of the ε2 allele (p<0.0001), suggestive of a moderate protective effect on hippocampal volume–an approximately 20% per allele volume increase as compared to CN with no ε2 alleles (Cohen’s d = 0.23). Conclusion Though no effect of ε4 was seen in CN subjects, our findings confirm and extend prior data on the opposing effects of the APOE ε4 and ε2 alleles on hippocampal morphology across the spectrum of cognitive aging.

Diagnostic utility of the Quick Inventory of Depressive Symptomatology (QIDS‐C16 and QIDS‐SR16) in the elderly

Doraiswamy PM, Bernstein IH, Rush AJ, Kyutoku Y, Carmody TJ, Macleod L, Venkatraman S, Burks M, Stegman D, Witte B, Trivedi MH. Diagnostic utility of the Quick Inventory of Depressive Symptomatology (QIDS‐C16 and QIDS‐SR16) in the elderly.

Donepezil Treatment in Patients With Depression and Cognitive Impairment on Stable Antidepressant Treatment: A Randomized Controlled Trial

OBJECTIVE Depression and cognitive impairment are often comorbid in older adults, but optimal treatment strategies remain unclear. In a two-site study, the efficacy and safety of add-on donepezil versus placebo were compared in depressed patients with cognitive impairment receiving stable antidepressant treatment. METHODS A randomized, double-blind, placebo-controlled trial was conducted in older adults with depression and cognitive impairment (https://clinicaltrials.gov/ct2/show/NCT01658228; NCT01658228). Patients received open-label antidepressant treatment for 16 weeks, initially with citalopram and then with venlafaxine, if needed, followed by random assignment to add-on donepezil 5-10 mg daily or placebo for another 62 weeks. Outcome measures were neuropsychological test performance (Alzheimers Disease Assessment Scale-Cognitive subscale [ADAS-Cog] and Selective Reminding Test [SRT] total immediate recall) and instrumental activities of daily living (Functional Activities Questionnaire). RESULTS Of 81 patients who signed informed consent, 79 patients completed the baseline evaluation. Open antidepressant treatment was associated with improvement in depression in 63.93% responders by week 16. In the randomized trial, there were no treatment group differences between donepezil and placebo on dementia conversion rates, ADAS-Cog, SRT total immediate recall, or FAQ. Neither baseline cognitive impairment severity nor apolipoprotein E e4 genotype influenced donepezil efficacy. Donepezil was associated with more adverse effects than placebo. CONCLUSION The results do not support adjunctive off-label cholinesterase inhibitor treatment in patients with depression and cognitive impairment. The findings highlight the need to prioritize discovery of novel treatments for this highly prevalent population with comorbid illnesses.