Determinants of psychomotor speed among 61 pairs of adult male monozygotic twins.

BACKGROUND: Declining psychomotor speed is an indicator of the aging process, and it is influenced by genetics and environmental factors. The present study examined the relative effects of familial aggregation (reflecting a combination of genetics and early environmental influences), and occupational, lifestyle, and health factors on psychomotor speed. METHODS: Hand and foot psychomotor speed was studied with 61 pairs of monozygotic male twins aged 35-67 years from the population-based Finnish Twin Cohort. The determinants of visual simple and choice reaction times were analyzed with multiple regression analysis. RESULTS: Familial aggregation, reflecting genetic influences and shared environmental effects, explained in mean 47% of decision times, 31% of movement times, and 37% of response times (decision time and movement time combined). Age, cardiovascular morbidity, lifetime vigorous and frequent exercise participation, and mean lifetime daily hours sitting at work explained 0-19% of hand psychomotor speed and 0-10% of foot speed, depending on the outcome. The predicted increase in decision times due to the presence of cardiovascular morbidity was 11-35 ms. The predicted increase for hand and contralateral foot response times between ages 45 and 55 was 18-41 ms. Smaller effects were noted for each year of strenuous exercise and each hour/day of average lifetime sitting at work. CONCLUSIONS: Results indicate that cardiovascular status, age, strenuous exercise, and work play a role in psychomotor speed, but a rather minor one. In contrast, genetic and shared early environmental influences as revealed from familial aggregation were relatively strong, yet a major proportion of the variability in psychomotor speed remained unexplained.

The effect of lifelong exercise on psychomotor reaction time: a study of 38 pairs of male monozygotic twins.

PURPOSE: The aim was to study the effect of lifetime physical activity on psychomotor speed. METHODS: Foot and dominant hand visual simple and choice psychomotor reaction times were studied among monozygotic twins (38 pairs) aged 35-69, discordant for lifetime exercise histories. RESULTS: There was a trend that some components of psychomotor reaction time were faster for frequent than for occasional exercisers, but the findings were not consistent for the hand and feet. After controlling for occupational physical activity, only choice decision time for the hand (26 ms, P < 0.01) and choice reaction time for the contralateral foot (51 ms, P < 0.05) both remained 7% faster. There was no trend for systematic differences in reaction times between twins engaged in regular exercise versus their siblings exercising infrequently. CONCLUSIONS: Results suggest a somewhat smaller effect of exercise than reported in previous studies. Reaction time may be significantly affected only by vigorous, frequent exercise. Thus, health promotion through exercise may be unlikely to have notable effects on reaction time.

Differences in psychomotor reaction time in male monozygotic twins discordant for lifetime cigarette smoking.

The effects of long-term cigarette smoking on psychomotor reaction time were investigated among 8 pairs of monozygotic male twins highly discordant for lifetime smoking (means 32.4 versus 0.6 pack-years). The men had no diagnosed cardiovascular disease or other major diseases, musculoskeletal complaints, or vision problems that might interfere with reaction time testing. The twins had similar education, work, and exercise histories; alcohol and coffee consumption and exposure to solvents were examined as possible confounds. Direct comparison of cotwins also controlled for age, genetics, and possible early environmental factors. Simple and choice reaction time were measured in the dominant hand and in both feet. The decision-time component of total reaction time was of primary interest. On average, long-term smokers had slower decision times than their nonsmoking twins; however, the differences were small (5 to 14%) and were not statistically significant for four of the six decision-time measures, perhaps due to the lack of power with only eight twin pairs. Further study may confirm our evidence suggesting that long-term cigarette smoking impedes reaction time, a key measure of function of the central nervous system.

Comparison of foot and hand reaction times among men: a methodologic study using simple and multiple-choice repeated measurements.

The primary study goal was to compare visual simple and choice reaction times of the hand and foot to assess validity of measurements for evaluating subjects' ability to perform rapid, controlled movements. First, we examined the repeatability (N = 34) for four different data-sampling methods from a series of 12 trials within sessions and between two test sessions. Simple and choice reaction times with the preferred hand and both feet were then compared among 153 healthy male volunteers aged 35 to 67 years. Pearson correlations for hand and ipsilateral and contralateral foot reaction times on simple and choice tasks (.53 to .80, p < .001) showed that psychomotor foot reaction time is a valid method for study of neuromuscular control of lower extremities.

Factors associated with exercise lifestyle--a study of monozygotic twins.

Regular exercise is widely advocated for a broad range of health issues. Yet, the association of familial factors (i. e. both genetic and childhood environmental factors) and specific environmental factors (not shared by family members) as well as health behavior with lifelong exercise participation is currently poorly understood. A total of 117 monozygotic male twin pairs aged 35 - 69 y (mean age 49 y), recruited from the population-based Finnish Twin Cohort, were studied. A summary outcome exercise variable was created by calculating the mean hours of exercise per week from 18 y of age to present from data provided from a structured interview. Suspected factors associated with exercise were analyzed with linear regression, while pairwise relationships were analysed using polychoric correlations and structural equation modeling. There was substantial familial aggregation in adulthood exercise, accounting for 43 % of all variation in exercise using the LISREL model. Factors associated with enhanced adherence to exercise in adulthood were participation in exercise and competitive sports in adolescence (from age 12 to 18). Education, age, number of chronic diseases, smoking, alcohol use, marital status, number of children and number of changes in residence were not associated with exercise adherence in adulthood. Our results suggest that early childhood environmental factors strongly influence exercise level throughout the lifespan. Therefore, interventions aimed at enhancing lifelong exercise participation may achieve more beneficial long-term results by targeting families and other childhood and adolescent environments.

Differences in hand and foot psychomotor speed among 18 pairs of monozygotic twins discordant for lifelong vehicular driving.

The purpose of this study was to examine driving as a determinant of hand and foot psychomotor reaction times. Visual simple and choice hand and foot psychomotor reaction times were measured. The occupational driving contrast was determined by an interview reviewing every job held during each subject's lifetime. Comparison was made of psychomotor speed among 18 pairs of 39- to 62-year-old monozygotic male twins discordant for lifelong occupational driving. The mean discordance was the equivalent of 16 years of full-time driving. The twins who drove more tended to have slower hand simple and choice reaction times, although only the difference in hand-choice decision time was statistically significant (32 ms, P < 0.05). The drivers also had slower ipsilateral foot-choice decision times (21 ms, P < 0.01), but on average they had faster reaction times in 8 of the 12 ipsilateral and contralateral foot measurements. The slightly longer decision times could be related to some general harmful effects of driving, possibly whole-body vibration. Faster foot movement times of drivers may be affected by practice effects of rapid lower-extremity movements in driving.