ABSTRACT

Insulin and insulin resistance likely play a significant role in the pathophysiology and cognitive decline associated with Alzheimer's disease (AD). Insulin, insulin receptors, and insulin-sensitive glucose transporters are selectively localized the brain, including medial temporal areas that support memory. Raising brain insulin levels can facilitate memory and increase cerebrospinal fluid levels of β-amyloid (Aβ) and inflammatory markers. Insulin's effects on cognition may reflect normal regulation of glucose metabolism, long-term potentiation, and neurotransmitter levels. Consequently, insulin abnormalities may disrupt normal memory functioning and promote pathophysiological processes observed in patients with neurodegenerative disorders. Conversely, restoring normal insulin activity may exert a beneficial effect on pathophysiological processes. For example, peroxisome proliferator-activated receptor (PPAR)-gamma agonists (insulin sensitizing agents used to treat type 2 diabetes mellitus) modulate neuronal cell survival, inflammatory responses, mitochondrial functioning, and possibly Aβ processing and deposition. One PPAR-gamma agonist, rosiglitazone, facilitates memory and modulates plasma Aβ levels in patients with AD. Likewise, a healthy diet and regular exercise may improve insulin sensitivity and decrease the risk for both AD. Furthermore, intranasal insulin administration rapidly delivers insulin to the brain without altering plasma insulin or glucose levels. Studies to date suggest that this procedure can facilitate memory and modulate plasma Aβ levels in memory-impaired adults. Interestingly, the adverse effects of insulin abnormalities and the beneficial effects of improving insulin sensitivity may differ by apolipoprotein E (APOE) genotype, an established risk factor for AD. Patients who do carry lower doses of the APOE e4 allele have an enhanced risk for insulin abnormalities and are also more responsive to the memory enhancing effects of both rosiglitazone and intranasal insulin administration, relative to other patients. Therefore, future therapeutic trials should consider the moderating effects of APOE genotype.

ABSTRACT

Background: Antidepressant effects have been demonstrated with both high-frequency left-sided repetitive transcranial magnetic stimulation (rTMS) (HFL-TMS) and low-frequency stimulation to the right prefrontal cortex (LFR-TMS). However, doubts remain about the extent of these reported treatment effects. Design and Methods: The study was a 6 week double-blind randomized sham-controlled trial of sequential bilateral rTMS (SBrTMS) in depression. The method consisted of 3 trains of LFR-TMS of 140 s duration at 1 Hz being applied daily followed immediately by 15 trains of 5 s duration of HFL-TMS at 10 Hz. Sham stimulation was applied using identical parameters, but with the coil angled at 45 degrees from the scalp resting on the side of one wing of the coil. Results: There was a significant difference in response between the two groups at the 2-week time-point (F(1,25) = 25.5, p < 0.001) and for the full duration of the study (F(5,44) = 3.9, p = 0.005). A significant proportion of the active study group met response (11/25) and remission criteria (9/25) by study end compared to the sham group (2 and 0/22). Interpretation: Bilateral rTMS treatment, involving the sequential application of both HFL-TMS and LFR-TMS, has substantial treatment efficacy in patients with treatment-resistant depression. The treatment response is clinically significant following 4–6 weeks of active treatment. Therefore this novel style of bilateral rTMS has the potential to become a substantive clinical intervention, although the study requires replication.

ABSTRACT

Background: Tramiprosate (3-amino-1-propanesulfonic acid, 3APS, ALZHEMED™) is an investigational product candidate that is believed to reduce amyloid deposition in the brain by binding to soluble Aβ, thereby slowing or halting the progression of Alzheimer Disease (AD). Design and Methods: We assessed the safety, tolerability, and pharmacokinetic/pharmacodynamic profiles of tramiprosate in a randomized, double-blind, placebo-controlled Phase II study in which 58 subjects with mild-to-moderate AD were randomly assigned to receive placebo or tramiprosate 50, 100, or 150 mg BID for 3 months. At the end of the double-blind study, 42 of these patients entered an open-label extension study in which they received tramiprosate 150 mg BID for an additional 17 months. Assessments included plasma and CSF tramiprosate concentrations, CSF Aβ42 concentrations, and psychometric tests (Alzheimer's Disease Assessment Scale – cognitive subscale, Mini-Mental State Examination, and Clinical Dementia Rating Scale – Sum of Boxes). Results: Tramiprosate had no significant impact on vital signs or laboratory test values. The most frequent side effects were nausea, vomiting, and diarrhea, which were intermittent and mild-to-moderate in severity. Overall, six tramiprosate-treated patients discontinued because of side effects (all causalities) and there were no drug-related serious adverse events. Tramiprosate crossed the blood–brain barrier and dose-dependently reduced CSF Aβ42 levels after 3 months of treatment. There were no psychometric score differences between treatment groups after 3 months of double-blind treatment. However, psychometric score changes over the 17-month open-label extension study are consistent with a slowing of cognitive and clinical decline, particularly in mild subjects. Interpretation: Long-term administration of tramiprosate is safe and tolerated in patients with mild-to-moderate AD. The short-term reduction of CSF Aβ42 levels and the long-term open-label cognitive and clinical assessments are consistent with disease-modification.

ABSTRACT

A key obstacle to the development of new drugs to treat the cognitive deficits of schizophrenia was the absence of a standard by which to measure their efficacy. Before granting approval for any new drug for this condition, the US Food and Drug Administration wanted a standard cognitive endpoint based on a broad consensus-based method. To address this obstacle, the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) intiative oversaw a process to develop a consensus neurocognitive battery. Its development included a ten-step process that is described in this article.