INTRODUCTION:

Throughout the globe, it is estimated that nearly one among three older adults experience falls each year. The above mentioned point is for those who are considerably healthy and active . The most common reason of falls in these masses is due to stepping and tripping over an obstacle¹. As the age increases, there is deterioration in the cognition and so performing dual tasks at a time becomes very difficult.

It is noted that old adults with age related reduced cognition tend to struggle while they are subjected to perform dual tasks.². There are various causes identified by the researchers in clinical practice which predispose to falls.

In countries like USA, where people live a luxurious life are always at the brink of such health problems .One reason behind his may be the reduced reactance of individuals with environment. India is the second most populous country consisting of 7.7% of total world population. Unlike, certain developed countries like USA, Indian population have a considerable reaction with the environment related falls. Hence, it is considered as one of the major problems of the elderly and thus tends to pose a great threat to the society ³.

It is imperative to know what actually fallers do in order to revert a fall. There are certain strategies taken up by the old adults in order to avoid a fall. Since, the well known reason predisposing to a fall is by tripping and falling over an obstacle, it would be very interesting to observe the kind of strategies assumed by the elderly they tend to adapt to certain rigid postures while they have to negotiate obstacles ⁴. Two important techniques are being used by the elderly in order to avoid obstacles are to either go around the obstacle or step over the obstacles⁵. By stepping over the obstacles, the individuals tend to alter their foot trajectories. In addition to these techniques adopted commonly, one such strategy is also used. Walking is an inevitable activity which is a part of the lifecycle of the human beings. Different individuals possess different strides on various surfaces. Some old adults tend to walk with short steps in order to make an effort to negotiate an obstacle ⁶. Environment serves as a potent threat to the olds who are frequent fallers or for those who are at the risk to experience falls ⁷.

Cognitive interference may influence obstacle crossing but the strength and nature of this influence is unclear. With advancements in age walking becomes challenging among old adults. They tend to overestimate heir fitness which forces them to land their foot in wrong trajectories⁸. Simple tasks however do not cause much difference in normal walking, however, complex tasks while walking can lead to falls. Subjects of old age with compromised neuromuscular system are at high risk to experience a fall. While normal walking subjects always have to undergo dual task scenarios. Certain obstacle avoidance tasks and self efficacy is required to deal with these situations⁹.

There is a phenomenon which enhances the cognition which is called the divided attention. It refers to performance of several simple to complex tasks at a time .Attention can be divided in many ways; however in young adults it may not cause any significant performance impairment. But in old adults, walking with attention division or with a dual task scenario tends to interfere with the former. When an obstacle is projected in the way of old adults they tend to take an increased time to negotiate the same¹⁰. There are certain studies being conducted to evaluate the diminished cognition of the olds. In daily life, people have to walk on many surfaces, precisely obstacles of various properties.¹¹.

Tripping over obstacles and imbalance during gait was reported as two of the most common causes of falls in the elderly. Imbalance of the whole body during obstacle crossing may cause inappropriate movement of the lower extremities and result in foot-obstacle contact. It is also noted that dual task related gait changes also lead to falls.¹². Hence, when old adults are forced to dynamic activities, they must control their momentum while approaching the object.

Walking while talking is an everyday phenomena in the normal life. However, adults with diminished cognition can feel challenging to do so., those people cannot cope up with the attention demands and thus it results in falls.^13,14It is also noted that when subjects fail to generate words ,while walking, they may also possess a diminished cognition.

In this study, thirty considerably healthy old adults were recruited. They were of similar age groups so the comparison becomes a significant one because there was no point comparing young and olds as they may have contrasting features. Subjects had to negotiate obstacles under single task and dual task in the form of walking along with verbal fluency. .Thus, the idea was to compare performance impairments when their attention was divided while they negotiated virtual obstacles.

METHODS:

PARTICIPANTS:

Sixty community dwelling individuals were recruited from 70 volunteers based on the inclusion criteria. They were divided into two groups. Group A comprised of 30 subjects aged between 51-60 years, young olds (mean=54.2, SD=2.89). Group B comprised of another 30 subjects aged between 61-70 years, olds (mean= 64.8, SD=3.26). Inclusion criteria were the ability of the subjects to walk normally without any walking aids such as crutches, canes etc., normal cognition and a significant neuromuscular co-ordination. All participants attained a Mini mental state examination score> 25. After collecting the basic demographic data’s, the subjects were fully explained about the benefits of participating in the study and asked to fill the consent form in acceptance with participation of the study which is duly signed by the participants and the researcher. There were no significant differences in the scores among the two groups. All subjects gave written informed consent prior to data collection.

MATERIALS:

All participants walked along a 10 metre pathway at a comfortable gait speed. The pathway comprised of chalk markings in every two metres. Red and green torch lights were used as virtual obstacles which were projected in the pathway as the subjects walked. The performance of the subjects was recorded using a camera. The pathway was resilient and hassle free so that the subjects walked comfortably along the same.

PROCEDURE:

The intervention was conducted in three trials, i). Normal walk without obstacle negotiation ii). Normal walk with obstacle negotiation iii) Normal walk with obstacle negotiation in concurrence with word generation task. The first trial lasted for a minute for which gait speed of the subjects was recorded. The second trial lasted for three minutes for which subjects underwent attention division task in the form of obstacle negotiation. Red and green lights were projected in their way. The subjects were instructed to avoid red light and step upon the green light. Success and failure levels were recorded. In case of red light, success level referred to the avoidance of the light whereas failure level referred to the acceptance of the same. In case of green light, success level referred to the stepping upon the light whereas the failure level referred to the avoidance of the same. Gait speed of the subjects was recorded at the end of the trial. The third trial lasted for three minutes in which the subjects underwent attention division in concurrence with word generation.

Image(1) Subject avoids red light, (2) Subject steps upon green light.

VERBAL FLUENCY:

Verbal fluency is the ability to produce novel and context related responses to a given topic. It is traditionally examined using Controlled Oral Word Association Test (COWAT). The subjects were instructed to speak aloud as many words as possible that begin with the letters F, A, S for a minute each along with obstacle negotiation. In this test, valid words include proper English words and invalid words include plurals of the same and repetitions or other nonsense words.

BLINDING:

The statistician who conducted analyses was blinded to the group allocation by renaming the groups with numbers.

DATA COLLECTION AND ANALYSIS:

The age, sex, gait speed in subsequent trials, success and failure levels were tabulated. The gait speed of the subjects was compared statistically using T-Test for independent samples. The obtained tabulations and graphical representations are given below

Fig 1: Graph showing mean of the gait speed in all three trials

Fig 2.

Fig 3.

Fig 2, 3 Graphical representation showing means of the success and failure levels in second and third trials during obstacle negotiation

The above values were obtained by summing up the words generated by each subject and tabulating them. Thus, the mean,, standard deviation, p value at a 0.05 level of significance were calculated. The p value, 0.0233 obtained is less than 0.05 significance level. Hence, it can be inferred that there was a significant difference among the two groups while they generated words. The olds encountered a great challenge while performing attention division task in concurrence with word generation task.

RESULTS:

Table 1; Mean and Standard Deviation of the Gait Speed in all 3 trials

TRIAL	GROUP A		GROUP B		P VALUE	SIGNIFICANCE LEVEL
TRIAL	MEAN	SD	MEAN	SD	P VALUE	SIGNIFICANCE LEVEL
1	56.07	4.37	52.39	4.65	0.0170	0.05
2	46.63	5.39	42.24	5.55	0.0182	0.05
3	37.21	8.16	30.15	7.64	0.0105	0.05

In the first trial, (p value 0.0170), both young olds and olds were quite comfortable as they were walking at a normal gait speed without any divided attention task. However, the gait speed of young olds was more than that of the olds.

In the second trial, (p value 0.0182), the subjects faced a considerable challenge while walking as they were instructed to negotiate the obstacles simultaneously. The olds assumed a posture prote3ctive method to avoid red obstacle. However, the young olds had minimal performance impairments when compared to those of olds.

Table 2; Mean And Standard Deviation Of Word Generation Task

	Group A	Group B
Mean	20.733	16.467
Standard deviation	6.341	4.734
P value; 0.0233	Significance level; 0.05

In the third trial, (p value 0.0105) the subjects underwent both attention division along with word generation tasks. The words generated by the subjects had no relations with their age as both groups generated some valid words with some exception. However, the olds faced a greater challenge when the demands for attention increased.

DISCUSSION:

The main aim of the study was to determine whether divided attention would affect olds more than young olds in their abilities to negotiate obstacles. However it was noticed that both the age groups negotiated obstacles in a different way. The subjects of the greater age group that is between 61 to 70 years assumed a Posture- protective strategy to negotiate obstacles. They did this by shortening those steps. This type of pattern was recorded in the literature. Adults of Higher age groups deal with the obstacles mainly by two ways. On seeing an obstacle the subjects tend to either step aside or step over the obstacle¹⁵. They also tend to shorten their steps when they have to deal with the obstacles. However in this study it was noted that the subjects stopped as soon as they saw the virtual obstacle in their path. To be precise the subjects between 65 to 70 years stopped as soon as they appreciated the virtual obstacle. However some of the subjects stepped aside or stepped over the red light. While doing this the subjects also hesitated on seeing the green light. That is why when the subjects stopped near the green light for a second but stepped on it, it was recorded as a failure level.

In the first trial, the subjects walked with a comfortable gait speed. Their gait speed was somehow not altered when they were supposed to negotiate obstacles in the second trial. A significant difference was noted in their gait speed while performing third trial. The possible reason maybe an increase in the attention demands¹⁶. In the third trial, the subjects did not negotiate obstacles while generating words. Due to an increase in the demand of cognition the subjects could perform either the divided attention task or the word generation task¹⁷. There were also certain instances in which the subjects did not walk at all unless they generated few novel words.

Among the two virtual obstacles one being red and the other being green, the red light was supposed to be avoided where as the green light was supposed to be stepped on. Few subjects were quite comfortable with obstacle avoidance where as the others were comfortable with obstacle stepping^{18, 19}. Due to this, few of the subjects committed pattern of errors where as other subjects did not commit such pattern of errors. Interestingly, some subjects were very tentative regarding obstacle avoidance, hence while avoiding red obstacle they also avoided the green obstacle²⁰. On the contrary, the subjects who were comfortable with obstacle stepping stepped on both green and red obstacles. These patterns of errors were quite interesting to view upon.

Surprisingly, the gait speed did not sufficiently depend on the age as the subjects of higher age walked at a considerably brisk pace. However, there was a significant reduction in their performance as they underwent both divided attention and word generation tasks simultaneously²¹. Whenever the subjects committed an error while obstacle negotiation, they were notified regarding the same. Few subjects assumed a tentative approach towards the obstacles while the others were quite confident to look out for those virtual obstacles.

In concurrence to attention division, the subjects were instructed to generate English words starting from letters, F, A and S for one minute each in the third trial. Proper nouns and repetition of words were not accepted. In case the subjects did so, they were notified. Numbers of valid words were recorded. Words such as ‘sun’ and ‘son’ were accepted when the subjects specified those words. It was observed that, there was no considerable impairment in the cognition of both age groups as they were successful to generate valid words with some exceptions. Word generation did not correspond to the age. Subjects with a decreased command over the language also generated acceptable valid words.

CONCLUSION:

Both young olds and olds had a significantly increased risk of obstacle contact while negotiating obstacles when their attention was divided, but dividing attention reduced obstacle avoidance abilities of the old significantly more than it did in the young. Diminished abilities to respond to physical obstacles present in the environment when attention is divided elsewhere may partially account for high rates of falls among the elderly. As the age increases, there is a reduction in cognition and neuromuscular co-ordination which tends to increase a greater risk of falls among the elderly while negotiating physical obstacles or hazards in the environment.

ACKNOWLEDGEMENT:

I would like to thank the authorities of Dr. MGR Educational and Research Institute, for providing me with facilities required to conduct the study.

Ethical Considerations:

The manuscript is approved by the Institutional Review board of faculty of physiotherapy. All the procedures were performed in accordance with the ethical standards of the responsible ethics committee both (Institutional and national) on human experimentation and the Helsinki Declaration of 1964 (as revised in 2008).

CONFLICT OF INTEREST:

Conflicts of interest: none'

FUNDING:

This is a self-funded study.

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Received on 23.04.2018 Modified on 11.06.2018

Research J. Pharm. and Tech 2018; 11(11): 5024-5028.

DOI: 10.5958/0974-360X.2018.00916.2