Significant cognitive improvements can arise from a relatively brief dietary intervention, and the improvements from a high soya diet are not restricted to women or to verbal tasks.

The N-methyl D-aspartate receptor complex is involved in the mechanism of long-term potentiation, which is thought to be the biological basis of learning and memory. This complex can be manipulated in a number of ways, one of which is through the strychnine-insensitive glycine receptor coagonist site. The effects of Bioglycin(Konapharma, Pratteln, Switzerland), a biologically active form of the amino acid glycine, were therefore studied in healthy students (mean age, 20.7 years) and middle-aged men (mean age, 58.9 years) with tests that measured attention, memory and mood, using a double-blind, randomized, crossover design. Compared with the young group, the middle-aged group had significantly poorer verbal episodic memory, focused, divided, and sustained attention; they also differed in their subjective responses at the end of testing. Bioglycin significantly improved retrieval from episodic memory in both the young and the middle-aged groups, but it did not affect focused or divided attention. However, the middle-aged men significantly benefited from Bioglycin in the sustained-attention task. The effects of Bioglycin differed from those of other cognitive enhancers in that it was without stimulant properties or significant effects on mood, and it primarily improved memory rather than attention. It is likely to be of benefit in young or older people in situations where high retrieval of information is needed or when performance is impaired by jet lag, shift work, or disrupted sleep. It may also benefit the impaired retrieval shown in patients with schizophrenia, Parkinson's disease, and Huntington's disease.

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In an open study, self-ratings of bodily symptoms, mood (before and after stress), and cognitive performance were investigated in 25 women (aged 54-66 years) who for approximately 10 years had been taking an oral preparation of hormone replacement therapy (HRT), tibolone (Livial; 2.5 mg/ day). Tibolone has a unique profile, with estrogenic, progestogenic, and androgenic actions. The control group of 25 women had never taken HRT. Each woman in this group was pair-matched to one in the tibolone group on age, years since menopause, IQ, years of secondary education, and occupation. The groups were matched on their anxiety and depression scores on the Hospital Anxiety and Depression rating scale. Exclusion criteria were scores on this scale in the clinical range and any current illness or recent use of psychoactive medication. The women who were taking tibolone felt significantly less clumsy and had less severe palpitations than the control group. After exposure to a mildly stressful test, the control group felt more anxious, but this change was not seen in the group receiving tibolone. The group taking tibolone had significantly better semantic memory (memory for facts), as assessed in a category generation task, but they did not differ in tests of episodic memory (memory for events). An unexpected finding was that the tibolone group performed significantly worse on a sustained attention task and a planning task, tasks that are associated with frontal lobe function. Our results suggest that the effects of HRT on cognition may be influenced by the type of HRT, the duration of treatment, the nature of the tests, and the brain region controlling the cognitive function.

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