WEBVTT Kind: captions Language: en 00:00:09.920 --> 00:00:14.240 okay uh good morning um i want to begin by uh thanking my 00:00:14.240 --> 00:00:18.560 colleagues today um you know certainly i think uh Joan 00:00:18.560 --> 00:00:20.800 set the tone when she asked if you know if 00:00:20.800 --> 00:00:24.960 water could actually improve cognition it wouldn't that be great and i 00:00:24.960 --> 00:00:28.800 hopefully i'll make a good argument for that um and then certainly 00:00:28.800 --> 00:00:35.040 my longtime colleague Naiman Khan set the tone talking about the details 00:00:35.040 --> 00:00:38.960 of this study and so where that leads me is today to 00:00:38.960 --> 00:00:44.800 go ahead and talk about cognition and so uh with that i just want to make 00:00:44.800 --> 00:00:47.920 a couple of points let me first actually go back 00:00:47.920 --> 00:00:50.399 and say i'll remind you again that this study is 00:00:50.399 --> 00:00:54.399 embargoed and so please do not take any pictures and i'll remind you 00:00:54.399 --> 00:01:02.879 again later on but two things about our study that i want to highlight again after 00:01:02.879 --> 00:01:07.439 Naiman's talk is uh first that we um we have a baseline commission 00:01:07.439 --> 00:01:11.119 and that sounds really basic but actually when you look through the 00:01:11.119 --> 00:01:15.439 literature on hydration or dehydration, hydration 00:01:15.439 --> 00:01:18.799 status and in children uh um when we're 00:01:18.799 --> 00:01:22.799 focusing on cognition there's no study prior to this one that took a 00:01:22.799 --> 00:01:25.680 baseline condition to check uh children's 00:01:25.680 --> 00:01:28.799 hydration status uh the second is is that there's no 00:01:28.799 --> 00:01:31.840 study out there that actually has looked at prolonged 00:01:31.840 --> 00:01:35.520 hydration status it's all been for the most part acute studies 00:01:35.520 --> 00:01:40.240 or uh cross-sectional evidence and so i think there's two very unique pieces 00:01:40.240 --> 00:01:44.960 um but as we move forward and we talk about, 00:01:44.960 --> 00:01:49.520 i want to set the background and so but in doing so i first i'm going to 00:01:49.520 --> 00:01:52.399 talk about hydration and then i'll talk about dehydration 00:01:52.399 --> 00:01:56.399 uh there's a couple studies out there uh Edmonds and 00:01:56.399 --> 00:01:59.439 Burford um they looked at visual attention 00:01:59.439 --> 00:02:04.000 uh and a number of other cognitive tasks in uh in 58 kids who were 00:02:04.000 --> 00:02:07.119 in two different classrooms and one condition they were asked to drink 00:02:07.119 --> 00:02:10.160 as much as possible in the other classroom they were 00:02:10.160 --> 00:02:15.040 they were withheld from having water and what they ultimately showed was that 00:02:15.040 --> 00:02:17.280 there were improvements in visual attention 00:02:17.280 --> 00:02:23.520 20 minutes after taking in 250 mls of water relative to when they withheld 00:02:23.520 --> 00:02:28.480 hydration or sorry um water and 00:02:28.480 --> 00:02:32.400 i point that out because they also collected other cognitive tasks no 00:02:32.400 --> 00:02:37.200 battery but didn't show any relationship so it's only uh visual attention and 00:02:37.200 --> 00:02:41.200 then um Fadda et al uh 00:02:41.200 --> 00:02:45.280 ran a similar design and a larger sample of kids uh first let me point out that 00:02:45.280 --> 00:02:48.480 out of the 168 children that they uh tested 00:02:48.480 --> 00:02:53.200 um 140 of them arrived at school in a mild dehydrated state 00:02:53.200 --> 00:02:56.319 so only 28 children arrived properly hydrated 00:02:56.319 --> 00:02:59.360 and again when they compared different conditions 00:02:59.360 --> 00:03:05.599 of either water intake they got about a thousand mls during the 00:03:05.599 --> 00:03:10.159 school day or um no no water intake that is say 00:03:10.159 --> 00:03:13.680 they're withheld from water uh what they found was an increase in 00:03:13.680 --> 00:03:16.879 working memory uh and short term memory working 00:03:16.879 --> 00:03:19.280 remember they're often times very similar they talked about 00:03:19.280 --> 00:03:22.560 i view this task as a working memory task and um 00:03:22.560 --> 00:03:25.680 what's interesting is that they also have measures of attention but they show 00:03:25.680 --> 00:03:29.200 no relationship there so there's a little bit of ambiguity and 00:03:29.200 --> 00:03:34.400 then more recently work by Perry actually has a fairly interesting design 00:03:34.400 --> 00:03:38.480 where they had kids drink 750 mls of water over two and a half 00:03:38.480 --> 00:03:43.519 hour two and a half hours or no water and uh and they looked at their baseline 00:03:43.519 --> 00:03:47.920 hydration status and what they what they did was uh they 00:03:47.920 --> 00:03:54.000 looked at change and so um in the in the the top figure 00:03:54.000 --> 00:03:59.680 is working memory the bottom figure is attention and they showed that kids 00:03:59.680 --> 00:04:04.640 who had the greatest change uh showed the least improvement 00:04:04.640 --> 00:04:07.920 in the water condition so here's the high change condition 00:04:07.920 --> 00:04:11.040 uh you can see that falling water intake they didn't 00:04:11.040 --> 00:04:14.400 uh show an increase in cognitive performance 00:04:14.400 --> 00:04:17.519 either for attention for working memory or for attention 00:04:17.519 --> 00:04:21.840 but those who are low hydrated uh in the low change condition or 00:04:21.840 --> 00:04:26.160 sort of the change was less they showed actually 00:04:26.160 --> 00:04:30.880 greater cognitive performance and so something about making drastic changes 00:04:30.880 --> 00:04:35.280 or at least large changes in uh in water intake lead to 00:04:35.280 --> 00:04:40.400 differences in cognitive performance now we look at dehydration as a good 00:04:40.400 --> 00:04:44.800 deal more literature out there um there's and so for that i'll focus on 00:04:44.800 --> 00:04:47.280 reviews there's reviews by uh Grandjean & Grandjean 00:04:47.280 --> 00:04:50.560 uh by Harris Lieberman who's here in the audience today by Nathalie Pross 00:04:50.560 --> 00:04:55.440 who's here in the audience today um and they've all shown that acute 00:04:55.440 --> 00:04:58.639 acute dehydrations relate to decreases in cognition 00:04:58.639 --> 00:05:03.120 across a variety of outcomes uh and that tends to appear somewhere 00:05:03.120 --> 00:05:08.080 around one and a half to two percent of body weight loss 00:05:08.840 --> 00:05:15.520 um uh a study by uh Ganio uh who's from uh i believe 00:05:15.520 --> 00:05:19.039 Dr. Armstrong's laboratory um but certainly he's authors as uh as 00:05:19.039 --> 00:05:21.919 is Harris Lieberman and a number of people from Danone are 00:05:21.919 --> 00:05:26.080 all authors in this paper they used a dehydration study or 00:05:26.080 --> 00:05:28.479 dehydration protocol i should say that included both 00:05:28.479 --> 00:05:33.759 exercise and and diuretics and they showed decreases in attention 00:05:33.759 --> 00:05:37.199 vigilance and working memory in young adults 00:05:37.199 --> 00:05:42.080 and then lastly bar david and colleagues uh found that dehydration uh status 00:05:42.080 --> 00:05:46.320 related to uh change in memory in school children 00:05:46.320 --> 00:05:49.600 and if you look at those data uh you can see here that 00:05:49.600 --> 00:05:54.400 uh some came in uh hydrated more came in dehydrated in the morning 00:05:54.400 --> 00:05:57.759 and the afternoon their status hadn't really changed 00:05:57.759 --> 00:06:02.160 uh as of according to osmolality uh when they looked at cognition in the morning 00:06:02.160 --> 00:06:06.080 they didn't show any differences between hydrated and dehydrated individuals 00:06:06.080 --> 00:06:09.919 however in the afternoon they showed that hydrated individuals outperformed 00:06:09.919 --> 00:06:14.000 dehydrated individuals on a working memory task 00:06:14.000 --> 00:06:17.440 now that's um that's interesting as as we've shown 00:06:17.440 --> 00:06:20.560 before but what's also interesting is again there's a number of cognitive 00:06:20.560 --> 00:06:24.960 tasks that appear unaffected and so uh at this point what i'd like to 00:06:24.960 --> 00:06:27.680 do is i'd like to talk about how we view cognition 00:06:27.680 --> 00:06:31.440 uh and give you a bit of a background on the the cognitive protocol 00:06:31.440 --> 00:06:36.080 and so uh cognition is the sentimental processes that contribute to perception 00:06:36.080 --> 00:06:39.840 memory intellect and action so this is basically your ability to think 00:06:39.840 --> 00:06:44.000 attend and to remember items in your environment or 00:06:44.000 --> 00:06:48.000 items that have previously been in your environment 00:06:48.000 --> 00:06:52.240 um cognitive functions assessed using a whole variety of different techniques uh 00:06:52.240 --> 00:06:55.039 paper and pencil is quite common particularly in schools 00:06:55.039 --> 00:06:58.240 uh neuropsychological testing is very common as well this is uh 00:06:58.240 --> 00:07:03.120 from clinical populations uh and beyond and and we prefer 00:07:03.120 --> 00:07:07.120 computerized testing this allows us the uh the freedom to tailor cognitive 00:07:07.120 --> 00:07:10.160 assessments particular samples or populations and 00:07:10.160 --> 00:07:13.039 really uh uh modify tests in order to make sure that we're 00:07:13.039 --> 00:07:16.800 getting uh a good representation of that cognitive function 00:07:16.800 --> 00:07:20.400 and then cognitive functions importantly are divided not only into the 00:07:20.400 --> 00:07:23.919 the domain that they capture but also into 00:07:23.919 --> 00:07:28.240 the aspects of brain or brain circuits that are involved or underlie that 00:07:28.240 --> 00:07:30.960 aspect of cognition and so we're talking about both 00:07:30.960 --> 00:07:36.000 behavior and brain and so today we're going to talk about executive 00:07:36.000 --> 00:07:39.360 control we're really interested in executive control it's the uh 00:07:39.360 --> 00:07:43.039 aspect of cognition that's intentional this is uh 00:07:43.039 --> 00:07:46.319 allows you to meet desired outcomes for instance if you're thirsty 00:07:46.319 --> 00:07:50.240 you reach for and grasp a bottle of water 00:07:50.240 --> 00:07:53.599 that is an intentional action it's not reflexive it's a 00:07:53.599 --> 00:07:56.960 it's a highly complex and scheduled action it's something that you do in 00:07:56.960 --> 00:08:00.479 everyday life executive control is particularly 00:08:00.479 --> 00:08:04.240 interesting children because it is among the last of the cognitive functions to 00:08:04.240 --> 00:08:06.720 develop it's tied to prefrontal cortex 00:08:06.720 --> 00:08:11.120 prefrontal cortex is among the last of the brain regions to develop as well 00:08:11.120 --> 00:08:15.680 um for those of us who are above 30 i'm sad to tell you that also the prefrontal 00:08:15.680 --> 00:08:19.840 cortex is the first to decay and so many of you should probably 00:08:19.840 --> 00:08:24.720 have a drink of water in order to enhance brain function 00:08:24.720 --> 00:08:28.720 situations that require executive function include uh when tasks are novel 00:08:28.720 --> 00:08:32.479 when we have to plan we have to problem solve we have to hold items in our mind 00:08:32.479 --> 00:08:36.800 you remember them um and so you know uh 00:08:36.800 --> 00:08:39.599 we use it all through our lives it's important for our mental and physical 00:08:39.599 --> 00:08:41.760 health important for school outcomes such as 00:08:41.760 --> 00:08:45.839 academic achievement school readiness it's important for our jobs and our 00:08:45.839 --> 00:08:48.480 successive jobs and interacting with individuals 00:08:48.480 --> 00:08:53.519 and if none of that convinces you it's also important for marital harmony 00:08:53.519 --> 00:08:57.200 and so we think about executive control in three different ways 00:08:57.200 --> 00:09:01.200 uh that is to say there's three aspects that cognitions generally agreed upon 00:09:01.200 --> 00:09:04.880 the three aspects of cognition comprise executive control the first is 00:09:04.880 --> 00:09:08.320 inhibition our ability to ignore distractions stay focused in theory 00:09:08.320 --> 00:09:11.120 you're all doing that right now paying attention rather than doing something 00:09:11.120 --> 00:09:14.240 else another good example might be as i walk 00:09:14.240 --> 00:09:17.600 through the halls of this beautiful hotel and i pass 00:09:17.600 --> 00:09:21.120 someone i say hello which is actually the wrong 00:09:21.120 --> 00:09:24.320 response because i am here in france i need to inhibit that response which is 00:09:24.320 --> 00:09:27.519 my typical strong representation of how to greet 00:09:27.519 --> 00:09:32.959 someone instead say bonjour um working memory it's our ability to 00:09:32.959 --> 00:09:35.360 hold information our mind and manipulate it 00:09:35.360 --> 00:09:38.880 we use this every day we do mathematics when you read a paragraph 00:09:38.880 --> 00:09:43.360 when you listen to this talk and have to remember something a couple slides later 00:09:43.360 --> 00:09:47.920 and then cognitive flexibility is actually typically called multitasking 00:09:47.920 --> 00:09:51.040 this this is what we all think we do really well we don't 00:09:51.040 --> 00:09:55.040 uh if we did we'd be allowed to text and drive but we're not 00:09:55.040 --> 00:09:58.080 that's because we do one task better than we do too 00:09:58.080 --> 00:10:01.680 cognitive flexibility paradigms though are much more complex in the sense that 00:10:01.680 --> 00:10:05.440 they allow us to uh execute multiple different executive functions and so for 00:10:05.440 --> 00:10:09.200 instance you might have a task where you execute a rule set 00:10:09.200 --> 00:10:12.079 you then inhibit that rule set but you have to hold it in working 00:10:12.079 --> 00:10:15.920 memory and execute a second rule set then you execute that rule set you 00:10:15.920 --> 00:10:18.640 inhibit it you hold it work in memory and go back to the first 00:10:18.640 --> 00:10:21.600 and so there's a number of different executive functions involved in 00:10:21.600 --> 00:10:26.079 cognitive flexibility tasks that elicit these types of 00:10:26.079 --> 00:10:29.279 cognitions include a flanker task that's uh where 00:10:29.279 --> 00:10:33.200 we might use fish or arrows and there's two conditions 00:10:33.200 --> 00:10:36.160 there's a condition here where all the stimuli are going the same 00:10:36.160 --> 00:10:38.800 direction the task is to look at the central fish 00:10:38.800 --> 00:10:41.920 and to press the button based on the direction the fish is swimming or an 00:10:41.920 --> 00:10:45.040 arrow racing direction arrow is pointing in a 00:10:45.040 --> 00:10:47.440 congruent condition it's quite easy you only have one 00:10:47.440 --> 00:10:51.040 rule set mapped right only one response uh mapped 00:10:51.040 --> 00:10:53.920 but in the in an incongruent condition it's a good deal more complex because 00:10:53.920 --> 00:10:57.519 you have to inhibit those flanking fish and instead focus on 00:10:57.519 --> 00:11:00.800 that target fish both responses are mapped and you have 00:11:00.800 --> 00:11:06.160 to select the correct response uh secondly we have another inhibition 00:11:06.160 --> 00:11:10.160 task called a go no-go task these are tigers and lions kids look at 00:11:10.160 --> 00:11:13.920 tigers they see tiger tiger tiger eventually you see that lion and they 00:11:13.920 --> 00:11:17.440 have to press a button pretty straightforward simple attention task 00:11:17.440 --> 00:11:20.480 but then we reverse it and we give them the same stimuli but different 00:11:20.480 --> 00:11:22.880 instructions and in this case what we do is we tell 00:11:22.880 --> 00:11:26.640 them to press the button every time i see that tiger so tiger tiger tiger 00:11:26.640 --> 00:11:29.440 but then when they get that line they have to inhibit their response and 00:11:29.440 --> 00:11:33.760 that's a response inhibition task another aspect of inhibition 00:11:33.760 --> 00:11:36.480 and lastly we have our cognitive flexibility test this one's quite 00:11:36.480 --> 00:11:40.399 difficult um you we have people who can stimulate 00:11:40.399 --> 00:11:44.160 they might make a color judgment is it blue or is it green blue green blue 00:11:44.160 --> 00:11:47.040 green um then they go and based on the and 00:11:47.040 --> 00:11:49.680 then they and the hands are pointing say upward 00:11:49.680 --> 00:11:53.120 uh then we have them do the task again similar stimuli uh 00:11:53.120 --> 00:11:57.200 they make a shape judgment square circle square circle 00:11:57.200 --> 00:12:00.639 uh but the hands are pointing down and then we give it to them all at once and 00:12:00.639 --> 00:12:04.079 so they get squares and circles and greens and blues 00:12:04.079 --> 00:12:07.680 and based on the direction of the hands they use that cue in order to execute 00:12:07.680 --> 00:12:10.560 the correct task so you can see where they have two tasks they can inhibit one 00:12:10.560 --> 00:12:15.440 execute the other it's a fairly difficult task and so 00:12:15.440 --> 00:12:18.720 uh the purpose of this study was to assess the effects of four days of 00:12:18.720 --> 00:12:20.109 changing hydration status 00:12:20.109 --> 00:12:23.120 high and low and as dr Khan said 00:12:23.120 --> 00:12:27.839 earlier our high was 2.5 liters each day for four days and our low was 00:12:27.839 --> 00:12:31.200 uh half a liter each day for four days and we compared it with a baseline 00:12:31.200 --> 00:12:34.480 hydration condition which we also now know is approximately about 00:12:34.480 --> 00:12:38.079 half a liter and we were interested in executive function 00:12:38.079 --> 00:12:41.760 in kids eight to ten years old uh we're going to look at the data two weights 00:12:41.760 --> 00:12:45.200 the first is group wise condition effects that is does the high condition 00:12:45.200 --> 00:12:48.320 differ from the low condition and from the baseline condition 00:12:48.320 --> 00:12:51.600 and uh within participant changes in hydration stats and so in this case 00:12:51.600 --> 00:12:55.920 we're looking individual differences in uh in their normal status and uh 00:12:55.920 --> 00:13:00.000 those differences when they change status so begin with 00:13:00.000 --> 00:13:04.399 hydration condition uh the first is that go nogo test the 00:13:04.399 --> 00:13:08.000 lions and tigers and what we see is that in the high 00:13:08.000 --> 00:13:11.200 hydration condition they perform better relative to the 00:13:11.200 --> 00:13:14.320 baseline and low condition they're better able to inhibit they're 00:13:14.320 --> 00:13:18.959 better able to execute uh the task in a correct uh 00:13:18.959 --> 00:13:22.800 in a correct manner we look at the flanker test the one with the fish 00:13:22.800 --> 00:13:26.800 and they have to find that middle fish we don't see a significant relationship 00:13:26.800 --> 00:13:30.240 but if you look to the more difficult condition when they have both responses 00:13:30.240 --> 00:13:33.360 mapped and have to have to single out the the correct 00:13:33.360 --> 00:13:38.160 response we do see the correct pattern and so that's encouraging that the cross 00:13:38.160 --> 00:13:40.800 inhibition tasks are at least seeing similar patterns 00:13:40.800 --> 00:13:46.079 one falling significant one not when we look at the cognitive flexibility task 00:13:46.079 --> 00:13:49.760 we look at three ways we first look at the global switch cost 00:13:49.760 --> 00:13:53.839 uh which showed a trend and marginal relationship 00:13:53.839 --> 00:13:58.079 uh and what we're looking at is reaction time speed the global switch cost 00:13:58.079 --> 00:14:03.120 is the difference between uh executing one task and executing two tasks and so 00:14:03.120 --> 00:14:05.839 in this case it's global you have the one task 00:14:05.839 --> 00:14:07.839 which is pretty straightforward and then two tasks 00:14:07.839 --> 00:14:11.680 you've enhanced working memory you've enhanced uh inhibition and you've 00:14:11.680 --> 00:14:14.320 enhanced cognitive flexibility and so we get a 00:14:14.320 --> 00:14:18.160 marginal relationship there we look at the local switch cost which 00:14:18.160 --> 00:14:22.320 is just selected to to the flexibility piece that is when 00:14:22.320 --> 00:14:25.360 they have to switch versus when they don't have to switch 00:14:25.360 --> 00:14:29.600 we don't see any relationship and then we look at the working memory cost that 00:14:29.600 --> 00:14:32.880 is what is the cost of holding two items in working memory versus holding one 00:14:32.880 --> 00:14:36.720 item of working memory we get a nice uh significant effect such 00:14:36.720 --> 00:14:40.320 that individuals are slower to respond in the low hydration 00:14:40.320 --> 00:14:42.320 condition suggesting that the low hydration 00:14:42.320 --> 00:14:48.959 condition influences their working memory and negatively 00:14:50.560 --> 00:14:54.480 next we're going to look at baseline hydration in this case for 00:14:54.480 --> 00:14:58.079 the question we're asking is what is the relationship between 00:14:58.079 --> 00:15:02.160 when they come to the laboratory in their normal hydrated state 00:15:02.160 --> 00:15:08.560 how does that relate to cognition and we find a nice global relationship 00:15:08.560 --> 00:15:12.160 with cognitive flexibility and so you're looking at along the x-axis 00:15:12.160 --> 00:15:15.680 you're looking at uh baseline you're in specific gravity 00:15:15.680 --> 00:15:18.800 on the y-axis we're looking at uh accuracy 00:15:18.800 --> 00:15:22.320 and whether they're performing one task or they're performing two tasks and 00:15:22.320 --> 00:15:27.760 switching between them we see that increases in uh 00:15:27.760 --> 00:15:32.399 in urine specific gravity you see decreases in performance 00:15:32.399 --> 00:15:36.800 and so the more hydrated individuals are the better they perform 00:15:36.800 --> 00:15:40.320 we also see the same effect regardless of whether they're switching from one 00:15:40.320 --> 00:15:43.440 task to another or whether they're repeating the same task 00:15:43.440 --> 00:15:48.320 and so it's a global effect however we did not see differences at baseline 00:15:48.320 --> 00:15:51.040 hydration for attentional inhibition or response 00:15:51.040 --> 00:15:54.720 inhibition and then lastly when we look at change 00:15:54.720 --> 00:15:57.759 in hydration status what we're looking at here is 00:15:57.759 --> 00:16:02.240 is the baseline condition uh urine specific gravity and the change 00:16:02.240 --> 00:16:06.160 to the high condition or the low condition and i'll tell you right now 00:16:06.160 --> 00:16:08.880 that given that the low condition the baseline condition 00:16:08.880 --> 00:16:11.920 were pretty similar we don't see any real relationships we'll see those 00:16:11.920 --> 00:16:14.639 figures uh but when we look at the change from 00:16:14.639 --> 00:16:17.839 baseline to high uh we look at the magnitude of that 00:16:17.839 --> 00:16:22.399 change and what we find is actually really kind of interesting this is just 00:16:22.399 --> 00:16:25.920 a reminder that or shown some of the data that demand 00:16:25.920 --> 00:16:29.839 showed a different way um the low condition very small change 00:16:29.839 --> 00:16:32.959 in urine specific gravity from 00:16:32.959 --> 00:16:36.959 baseline the high condition a much more significant change 00:16:36.959 --> 00:16:42.399 and so we look at cognitive flexibility our shapes and color tasks what we see 00:16:42.399 --> 00:16:44.399 is in the change to the high condition with an 00:16:44.399 --> 00:16:47.839 increased change in hydration status we see 00:16:47.839 --> 00:16:54.079 a decrease in uh accuracy and so those kids who came in 00:16:54.079 --> 00:16:58.880 with um most i said or lowest in hydration i want to say dehydrated but 00:16:58.880 --> 00:17:02.399 most uh low hydrated if that makes sense and 00:17:02.399 --> 00:17:06.160 then bump up to 2.5 liters a day they show a 00:17:06.160 --> 00:17:11.039 deficit in their cognitive performance we see it uh in in the homogeneous and 00:17:11.039 --> 00:17:14.400 the heterogeneous as the one task for the two task 00:17:14.400 --> 00:17:20.559 condition and we don't see it in the low hydration condition 00:17:20.559 --> 00:17:23.760 and then we look at the flanker test the task of fish or 00:17:23.760 --> 00:17:28.720 arrows uh what we we see a very similar effect it's marginal 00:17:28.720 --> 00:17:32.000 uh in the in the congruent condition the easy condition 00:17:32.000 --> 00:17:36.320 and in the incongruent condition again the greater the change in hydration 00:17:36.320 --> 00:17:39.039 status the the more poorly they perform with 00:17:39.039 --> 00:17:43.679 again no change in uh for the low condition and so uh 00:17:43.679 --> 00:17:47.840 with that i just want to mention a few mechanisms again the 00:17:47.840 --> 00:17:52.000 literature certainly is in need of of identifying mechanisms there aren't 00:17:52.000 --> 00:17:56.799 many that have been proposed in the literature and all of them i 00:17:56.799 --> 00:17:59.200 should say have to do with dehydration that is to 00:17:59.200 --> 00:18:02.960 say the mechanisms hasn't haven't been proposed for a lower or high hydration 00:18:02.960 --> 00:18:08.160 uh status and so the first is that fluid loss may lead 00:18:08.160 --> 00:18:11.360 to shrinkage and extracellular volume this is an acute 00:18:11.360 --> 00:18:16.880 change in brain as a function of of low hydration dehydration this 00:18:16.880 --> 00:18:21.200 relates to decreases in perfusion uh which is how his blood circulating 00:18:21.200 --> 00:18:25.360 through brain and dehydration is linked to cortisol 00:18:25.360 --> 00:18:31.600 which uh cortisol as many of you know is a stress response um but also uh 00:18:31.600 --> 00:18:36.000 cortisol is is linked to aspects of cognition as well such that 00:18:36.000 --> 00:18:40.160 uh increases in cortisol or the stress hormone related decreases in cognition 00:18:40.160 --> 00:18:44.320 in most cases we do occasionally see increases in cognition as well uh making 00:18:44.320 --> 00:18:47.360 it a little more uh variable uh vasopressin as well is 00:18:47.360 --> 00:18:50.880 linked to changes in attention um and these actually have a link to 00:18:50.880 --> 00:18:54.080 increases in attention so there is some contradictory findings in the literature 00:18:54.080 --> 00:18:58.559 that need to be clarified um and then it's also going to uh 00:18:58.559 --> 00:19:01.760 changes in neurotransmitters such as norepinephrine which is 00:19:01.760 --> 00:19:06.960 uh at the at the crux of um of attention and inhibition 00:19:06.960 --> 00:19:10.080 among other aspects of cognition and then i just want to 00:19:10.080 --> 00:19:13.919 point out one study there's really no or two studies by Kempton 00:19:13.919 --> 00:19:17.039 these are the only two studies of brain imaging in the field 00:19:17.039 --> 00:19:21.280 um and uh the first is a measure of brain structure 00:19:21.280 --> 00:19:24.720 and what they found was that uh with an increase 00:19:24.720 --> 00:19:30.080 in uh or increased loss of body mass they saw increases in the lateral 00:19:30.080 --> 00:19:33.120 ventricular enlargement that is the cavities within 00:19:33.120 --> 00:19:36.400 the brain suggesting structural differences these 00:19:36.400 --> 00:19:38.000 data were collected a number of years ago 00:19:38.000 --> 00:19:41.919 and our measures of of structure vastly improved since then so these this is a 00:19:41.919 --> 00:19:44.400 measure called vvm and now we're able to identify 00:19:44.400 --> 00:19:47.360 differences in white matter and gray matter independently of one another 00:19:47.360 --> 00:19:53.039 um and then his uh Kempton's second uh study was a dehydration protocol that 00:19:53.039 --> 00:19:56.000 led to changes in the bold signal blood oxygen level 00:19:56.000 --> 00:19:58.960 dependence signal which is how blood moves 00:19:58.960 --> 00:20:02.080 through the brain and they showed an increase in the bullet signal 00:20:02.080 --> 00:20:05.120 but no change in cognitive performance suggesting that it was a less efficient 00:20:05.120 --> 00:20:09.200 system and so in conclusion um this is the 00:20:09.200 --> 00:20:11.440 first clinical trial in children to assess 00:20:11.440 --> 00:20:14.640 baseline hydration uh to compare cognitive outcomes based 00:20:14.640 --> 00:20:19.440 on changes in hydration status uh children's baseline hydration was 00:20:19.440 --> 00:20:23.360 similar to the low intake condition and response 00:20:23.360 --> 00:20:27.200 inhibition and working memory improved during the high water intake condition 00:20:27.200 --> 00:20:31.520 uh compared to baseline and low intake condition and so we do see baseline or 00:20:31.520 --> 00:20:35.600 differences between conditions we also see differences at 00:20:35.600 --> 00:20:38.000 baseline where hydration was globally related to 00:20:38.000 --> 00:20:42.880 executive function across a cognitive flexibility task 00:20:42.880 --> 00:20:47.360 and greater change in hydration from baseline to high water intake condition 00:20:47.360 --> 00:20:51.039 was related to poor executive function across multiple 00:20:51.039 --> 00:20:54.640 different cognitive tasks such findings indicate that although 00:20:54.640 --> 00:20:58.799 greater hydration is related to better cognitive performance i think 00:20:58.799 --> 00:21:04.480 we have to issue caution at this time because uh changes in larger changes in 00:21:04.480 --> 00:21:07.039 water uh intake over what appears to be a 00:21:07.039 --> 00:21:10.640 relatively short period of time actually might relate to uh decay of 00:21:10.640 --> 00:21:14.000 cognitive performance so the implications of this research pertain to 00:21:14.000 --> 00:21:16.640 children's chronic hydration status and cognitive 00:21:16.640 --> 00:21:20.480 performance and how best to increase hydration in order to best benefit 00:21:20.480 --> 00:21:24.640 cognitive outcomes with that Naiman uh my colleague Naiman Khan did a 00:21:24.640 --> 00:21:27.760 great job of acknowledging all of our colleagues both 00:21:27.760 --> 00:21:30.960 at known and as well as those of us in the project uh certainly 00:21:30.960 --> 00:21:34.640 uh i have to thank Danone as well uh for funding the project and for their 00:21:34.640 --> 00:21:39.600 uh really constant support and help uh it's been a terrific relationship 00:21:39.600 --> 00:21:42.720 uh Naiman's already mentioned everyone and i'm at a time 00:21:42.720 --> 00:21:55.840 and so i think i will not be redundant and just thank you