Effects of diphenylhydantoin on mental abilities in the elderly

An assessment was made of the effects of diphenylhydantoin (DPH) on the mental functions of clinically normal elderly persons. Their basic intelligence levels ranged between normal and bright-normal and they represented middle and lower-upper socio-economic group. The 10 subjects, 4 male and 6 female volunteers (average age, 69.3 years), were given pretrial intelligence tests, repeated twice during a double-blind, cross-over study of drug and placebo effects. Each cross-over period lasted three weeks. The dosage of DPH (Dilantin) was 100 mg twice daily, and placebo capsuales of identical appearance were given on the same schedule. The Wechsler Intelligence Scale series in three alternate forms was used to measure specific mental functions. The weighted scores of the altervate forms were directly compared to measure the difference between drug and placebo conditions. Significant increases in favor of DPH were observed in the Information, Comprehension, and Digit Symbol subtests, and in the Verbal Scale and Full Scale Intelligence Quotients. The first two measures indicated significant improvement in long-term memory and social comprehension. The third reflected an increase in the ability to learn new material and increased speed in visual-motor coordination. The fourth and fifth showed the effectiveness of DPH in improving general mental functioning. Apparently the underlying factor synthesizing these general DPH-associated improvements is mental concentration.