Article

Reuters Health Information: June 2009


 

There were 1,640 cognitively normal subjects and 329 with mild cognitive impairment. Of the 329 subjects with mild cognitive impairment, 241 had amnestic impairment, and 88 had nonamnestic impairment. Overall, 183 subjects (9.3%) had a history of stroke.

In fully adjusted models with subjects free of dementia, an association was observed between a history of stroke and a higher odds ratio (OR) of nonamnestic mild cognitive impairment (OR, 2.85) than amnestic mild cognitive impairment (OR, 1.77). History of stroke was significantly associated with impaired function in each cognitive domain, with the exception of memory. The strongest association was found with decline in executive function (OR, 2.48).

The authors reported that APOE ε4 genotype was associated with amnestic mild cognitive impairment but not nonamnestic mild cognitive impairment, and with impaired memory function.

“There are several possible subclinical mechanisms that could account for the cumulative rather than apoplectic development of dementia due to cerebrovascular disease,” Dr. Knopman and colleagues explained.

“One is that prior strokes, in causing brain injury, reduce brain reserve, which allows the impact of subsequent diseases such as Alzheimer’s disease to be manifested clinically at an earlier time,” they pointed out.

“A second explanation posits that overt strokes are associated with progressive cerebral microvascular disease, with the latter leading to ongoing brain injury and eventually dementia.”

Arch Neurol. 2009;66(5):614-619.

Gene in Metabolic Disorder Linked to Parkinson’s Disease
NEW YORK, May 22 (Reuters Health) — Gene mutations responsible for a metabolic disorder called Gaucher’s disease may also play a role in the development of Parkinson’s disease, a Japanese study shows.

Gaucher’s disease is a rare hereditary disorder affecting the metabolism of a lipid composed of a ceramide and glucose. It occurs when mutations in the gene for glucocerebrosidase, or GBA, cause a deficiency of the enzyme needed to break down glucocerebroside, resulting in large accumulations of the lipid.

Dr. Tatsushi Toda from Osaka University Graduate School of Medicine, Japan, and colleagues conducted a detailed analysis of the GBA gene’s DNA sequence to identify all variants and investigated the association of these variants with Parkinson’s disease.

They found that 50 of 534 patients with Parkinson’s disease (9.4%) had detrimental variants of GBA, compared with only two of 544 subjects without Parkinson’s disease (0.37%). This represents a 28-fold increased risk of Parkinson’s disease among those with GBA mutations, the researchers reported in the May Archives of Neurology.

Furthermore, the onset of Parkinson’s disease occurred at a significantly younger age among patients with GBA variants than among those without GBA variants.

“This is the first robust susceptibility gene for Parkinson’s disease,” Dr. Toda commented. He added that the reason GBA variants lead to Parkinson’s will probably be uncovered soon, “since detailed functions of GBA have been established.”

Arch Neurol. 2009;66(5):571-576.

Learning Difficulties in Early and Late Perimenopause
NEW YORK, May 25 (Reuters Health) — Many women may not be able to learn as well shortly before menopause compared to other stages in life, according to a new study. After menopause, however, brain function improves to its premenopausal level.

The results of the study, which appear in the May 26 issue of the journal Neurology, also suggest that hormone therapy begun before the final menstrual period helps to boost cognitive function, while hormone therapy initiated after the last menstrual period may have a detrimental cognitive effect.

The findings stem from the Study of Women’s Health Across the Nation (SWAN), a four-year study looking at brain function during the menopause transition in 2,362 women.

The women were given tests of memory and a test that measured the speed at which they processed information throughout four stages of the menopause transition: premenopausal (no change in menstrual periods), early perimenopausal (menstrual irregularity but no “gaps” of three months), late perimenopausal (having no menstrual period for three to 11 months), and postmenopausal (no menstrual period for 12 months).

Taken together, the results suggest that during early and late perimenopause women do not learn as well as they do during other menopause transition stages.

“These perimenopausal test results concur with prior self-reported memory difficulties—60% of women state that they have memory problems during the menopause transition,” Dr. Gail Greendale from the University of California, Los Angeles, said in a statement.

As noted, the timing of hormone therapy initiation had an impact on cognitive performance. Taking estrogen or progesterone hormones before menopause helped memory and information-processing speed, but taking these hormones after the final menstrual period seemed to have a negative effect: postmenopausal women using hormones showed no improvement in either processing speed test scores or memory test scores, unlike postmenopausal women not taking hormones.

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