ABSTRACT. The effects of âMentatâ, an Ayurvedic herbal formulation, were examined on memory span, fluctuation of attention, galvanic skin resistance (GSR) ...
(Pharmacopsychoecologia (1990): 3, 39-42)
Effects of “Mentat” on Memory Span, Attention, Galvanic Skin Resistance (GSR) and Muscle Action Potential (EMG) among Normal Adults Aruna Agrawal, Manju Lata Dubey and G.P. Dubey Banaras Hindu University, Varanasi, India.
ABSTRACT The effects of “Mentat”, an Ayurvedic herbal formulation, were examined on memory span, fluctuation of attention, galvanic skin resistance (GSR) and muscle action potential (Electromyograph-EMG). Male and female university students served as subjects. A double blind procedure was adopted for drug administration. “Mentat” led to a statistically significant increase in memory span and GSR and a statistically significant decrease in fluctuation of attention and myographic potential (EMG), indicating multipoint effects of the herbal formulation. Key Words: Mental, memory span, attention, GSR, EMG. Anxiety and stress are the most common factors that affect memory adversely (see for reviews of such studies, Eysenck, 1977, 1981, 1982). Moreover, a progressive decline in memory with advancing age is also an established fact. The current research in this area focuses on finding ways to alter the neurochemical aspects of memory with a view to discovering a remedy that can overcome memory impairment. This research is based upon the assumption that some pharmacological formulation could be possible that might facilitate the neurotransmitters (such as acetylcholine, dopamine, serotonin, catecholamines etc.) presumed to play a vital role in the organisation of memory. The clinical neurophysiological evidence clearly indicates that the processes associated with recording and registration of information are hampered by anxiety and stress (Lance and McLeod, 1981). Grings and Dawson (1978) also point out that hyper-excitable individuals have a poor concentration ability probably due to sympathetic over activity. Such people have also reduced short term memory. In the recent times attention has been directed to search some drug remedy to increase the memory span for better mental performance. Ayurvedic literature mentions several herbs exerting favourable influence on brain function in general and memory in particular. “Mentat” is a herbal preparation containing several herbs like Hydrocotyle asiatica (Brahmi), Acorus calamus (Bachh), Withania somnifera (Ashvagandha), Tinospora cordifolia (Giloe), Evolvulus alsinoides (Shankhpushpi), Nardostachys (Jatamansi) in different doses. The combination of above herbs are processed according to the Ayurvedic principles. The present work has been designed to examine the effects of “Mentat” in normal student population. The physiological parameters like galvanic skin resistance (GSR) and muscle action potential (EMG) were utilised for the measurement of sympathetic activity. Since the memory impairment among students is a common problem, it was desirable to examine the effects of this preparation on memory and attention as well as galvanic skin resistance and electrical action muscle potentials of the occipito-frontalis muscle. Ayurvedic drugs are claimed to act through normal physiological mechanisms. There is a large variation in the memory span and attention in normal population. It was, therefore, decided to test the effects of “Mentat” in such a population.
MATERIAL AND METHODS Fifty adult students (28 males and 22 females), aged 19-26 years, from the faculty of science and technology provided data for the present study. None of the students reported any organic or psychological disorder in the recent past. Short-term memory span was measured by the method described by Strub and Black (1981). It was calculated in terms of scores out of the maximum possible score of 150. Fluctuation of attention was recorded by an electronic device (FM-1500). Galvanic skin resistance was measured by using a GSR feedback apparatus (GBF 2000, Medicaid System) at the sensitivity setting of 5 to 10 per second with a constant speed of 25 mm per second. Similarly, the occipito-frontalis potentials were recorded by placing electrodes on the occipitofrontalis muscle over forehead and with the help of an EMG feedback apparatus (MBF 4000, Medicaid System) at the sensitivity of 200 to 2000 microvolts with a constant chart speed of 25 mm per second. After initial investigations and necessary recordings for the basal state, “Mentat” was given at a dose of 2 tablets, b.i.d. to 18 male and 14 female students for a period of 3 months. Placebo was given in the same dose to 10 male and 8 female students for the same period, i.e. 3 months. The placebo tablets were prepared by using neutral substance like sugar identical to the “Mentat” tablets. All the investigations were repeated at monthly intervals upto 3 months. The initial values were compared with those at the end of 3 months. The ‘t’ test was used to test the significance of differences among the means of various psychological and physiological parameters. RESULTS The results of the study are presented in Tables 1 and 2. A significant increase in memory span and a significant decrease in fluctuation of attention was observed under the influence of “Mentat” at compared with placebo (Table 1). Similarly, the drug led to a significant increase in the GSR and a significant reduction in the occipito-frontalis electromyography (Table 2). Table 1: Effect of Mentat on memory span and fluctuation of attention in normal young adults Percent memory span Fluctuations of attention Mean ± SEM (per minute) Mean ± SEM Groups Sample size Initial 12 weeks Initial 12 weeks Placebo Male 10 87.81±6.58 89.78±7.29NS 16.74±3.12 17.89±2.98NS Female 8 89.02±7.97 92.50±8.39NS 16.22±3.87 17.98±3.68NS Mentat-treated Male 18 82.50±8.58 92.82±7.32* 16.11±2.76 13.98±2.48* Female 14 79.80±6.32 88.82±7.21 19.50±3.94 14.07±2.18** Memory span score of 150 is taken as 100%. The individual scores are converted to percentages and mean scores are given with standard errors. NS = Not significant * p
