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Memory & Cognitive function, focus & ADHD
Cognitive function in untreated hypothyroidism and hyperthyroidism.
Samuels MH. Curr Opin Endocrinol Diabetes Obes. 2008 Oct;15(5):429-33. Links
Oregon Health & Science University, Portland, Oregon 97239, USA. samuelsm@ohsu.edu
PURPOSE OF REVIEW: The brain is an important target organ for thyroid hormone, and alterations in mood and cognition may occur with thyroid dysfunction. Recent advances in the field of cognitive neurosciences have allowed more sensitive and focused testing of cognitive domains in patients with altered thyroid function.
RECENT FINDINGS: Based on recent population-based studies, there do not appear to be major deficits in cognitive functioning in overt or subclinical thyroid disease. However, interventional and functional imaging studies suggest that subtle deficits in specific cognitive domains probably do exist. The most commonly affected domains are working memory and executive function. Also present are alterations in mood, manifested by increased rates of depressive and anxiety symptoms.
SUMMARY: Patients with overt or subclinical thyroid dysfunction commonly complain of decrements in cognitive function, but studies suggest that such decrements are most likely to be minor or not related to the thyroid dysfunction. More common are mood alterations, which often improve with treatment.
"Brain-specific" nutrients: a memory cure?
McDaniel MA, Maier SF, Einstein GO.
Department of Psychology, University of New Mexico, Albuquerque, New Mexico 87131, USA. mcdaniel@umn.edu Nutrition. 2003 Nov-Dec;19(11-12):957-75
OBJECTIVE: We review the experimental evaluations of several widely marketed nonprescription compounds claimed to be memory enhancers and treatments for age-related memory decline. We generally limit our review to double-blind placebo-controlled studies. The compounds examined are phosphatidylserine (PS), phosphatidylcholine (PC), citicoline, piracetam, vinpocetine, acetyl-L-carnitine (ALC), and antioxidants (particularly vitamin E).
RESULTS: In animals, PS has been shown to attenuate many neuronal effects of aging, and to restore normal memory on a variety of tasks. Preliminary findings with humans, though, are limited. For older adults with probable Alzheimer's disease, a single study failed to demonstrate positive effects of PS on memory performance. For older adults with moderate cognitive impairment, PS has produced consistently modest increases in recall of word lists. Positive effects have not been as consistently reported for other memory tests. There is one report of consistent benefits across a number of memory tests for a subset of normal adults who performed more poorly than their peers at baseline. The choline compounds PC and citicoline are thought to promote synthesis and transmission of neurotransmitters important to memory. PC has not proven effective for improving memory in patients with probable Alzheimer's disease.
The issue remains open for older adults without serious degenerative neural disease. Research on citicoline is practically nonexistent, but one study reported a robust improvement in story recall for a small sample of normally aging older adults who scored lower than their peers in baseline testing. Animal studies suggest that piracetam may improve neuronal efficiency, facilitate activity in neurotransmitter systems, and combat the age-related decrease in receptors on the neuronal membrane. However, for patients with probable Alzheimer's disease, as well as for adults with age-associated memory impairment, there is no clear-cut support for a mnemonic benefit of piracetam.
Vinpocetine increases blood circulation and metabolism in the brain. Animal studies have shown that vinpocetine can reduce the loss of neurons due to decreased blood flow. In three studies of older adults with memory problems associated with poor brain circulation or dementia-related disease, vinpocetine produced significantly more improvement than a placebo in performance on global cognitive tests reflecting attention, concentration, and memory. Effects on episodic memory per se have been tested minimally, if at all.
ALC reverses the age-related decline in the number of neuron membrane receptors
ALC participates in cellular energy production, a process especially important in neurons, and in removal of toxic accumulation of fatty acids. Animal studies show that ALC reverses the age-related decline in the number of neuron membrane receptors. Studies of patients with probable Alzheimer's disease have reported nominal advantages over a range of memory tests for ALC-treated patients relative to placebo groups. Significant differences have been reported rarely, however. Whether ALC would have mnemonic benefits for aging adults without brain disease is untested as far as we know.
Antioxidants help neutralize tissue-damaging free radicals, which become more prevalent as organisms age. It is hypothesized that increasing antioxidant levels in the organism might retard or reverse the damaging effects of free radicals on neurons. Thus far, however, studies have found that vitamin E does not significantly slow down memory decline for Alzheimer's patients and does not produce significant memory benefits among early Parkinson's patients. Neither did a combination of vitamins E and C significantly improve college students' performance on several cognitive tasks.
CONCLUSIONS: In sum, for most of the "brain-specific" nutrients we review, some mildly suggestive effects have been found in preliminary controlled studies using standard psychometric memory assessments or more general tests designed to reveal cognitive impairment. We suggest that future evaluations of the possible memory benefits of these supplements might fruitfully focus on memory processes rather than on memory tests per se.
Efficacy and tolerability of a Rhodiola rosea extract in adults with physical and cognitive deficiencies.
Fintelmann V, Gruenwald J. Adv Ther. 2007 Jul-Aug;24(4):929-39.
Carl Gustav Carus Akademie Hamburg e. V., Hamburg, Germany.
During a 12-wk drug monitoring study, the efficacy and safety of a Rhodiola rosea extract given in combination with vitamins and minerals (vigodana(R)) were tested in 120 adults (83 women and 37 men, ages 50-89 y) with physical and cognitive deficiencies. Two different dosage regimens were chosen. One group of 60 patients (group 1) took 2 capsules orally in the morning after breakfast, and the other group (group 2) took 1 capsule after breakfast and 1 after lunch. Three medical examinations were performed during the course of the study (at baseline, after 6 wk, and after 12 wk).
The evaluated symptoms were divided into physical disturbances such as exhaustion, decreased motivation, daytime sleepiness, decreased libido, sleep disturbances, and cognitive complaints (eg, concentration deficiencies, forgetfulness, decreased memory, susceptibility to stress, irritability).
A statistically highly significant improvement (P<.001) in physical and cognitive deficiencies was observed in the overall group, as well as in the separately evaluated groups 1 and 2. In addition, the time needed to complete a digit connection test decreased significantly in all groups (P<.001). Improvements in group 1 were more pronounced than in group 2, however, indicating that the intake of 2 capsules after breakfast is more effective than the intake of 1 capsule after breakfast and 1 after lunch. Global assessment of efficacy revealed that treatment was "very good" or "good" for 81% of patients, as reported by physicians, and for 80%, as reported by patients.
Ninety-nine percent of patients and physicians rated safety as "good" or "very good." No adverse events occurred during the course of the study. The results of this drug monitoring study are very promising, but they still need to be corroborated by future placebo-controlled clinical trials.
Studies:
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