Using Frontal Brain Asymmetry to Control Sensory Treatment of

Anxiety and Depression

Tim J. C. Jacob

, Jeremy Warden-Smith

, Neil Kernot

and Malyka Galay Burgos

School of Biosciences, Cardiff University, Museum Avenue, Cardiff, U.K.

Chelker Technology, 16 Swadford Street, Skipton, North Yorkshire, U.K.

Keywords: Depression, Anxiety, EEG, Alphawaves, Frontal Asymmetry, Bright Light Therapy, Smell Stimulation.

Abstract: Anxiety and depression are increasingly common disorders. Globally, more than 350 million people of all

ages suffer from these illnesses. Depression and anxiety are treated with medication, psychotherapy, or

electroconvulsive therapy (ECT), either individually or in combination. Drugs and ECT are not cures and

often involve unpalatable adverse side-effects necessitating safer more sustainable alternatives. The

antidepressant properties of bright light are well established and aroma stimulation has been shown to improve

mood and reduce markers for anxiety and depression. A combinatory therapy of light and smell stimulation

has been shown to have a positive impact on mood, physiological markers for stress, anxiety and depression.

In particular, negative alphawave brain asymmetry, an objective marker for depression, is reduced by a 15min

stimulus treatment. The proposal outlined in this paper is that real-time frontal alpha asymmetry, recorded by

EEG, be used to control the frequency, duration and amplitude of the light and aroma signals to optimise the

effectiveness of the treatment. The object of this treatment is to rebalance the frontal asymmetry restoring a

frontal activity representative of a non-depressed, non-anxious state.

1 INTRODUCTION

It has been estimated that Common Mental Disorders

affect 1 in 6 British adults every week with over half

of these having a mixed anxiety and depressive

disorder (Deverill and King, 2009). In the USA, in

any given one-year period, 13 million to 14 million

people (which equates to approximately 6.6% if the

US population) experience depression (Kessler et al,

2003); globally, more than 350 million people of all

ages suffer from the illness (WHO, 2012) and the

annual incidence in UK is 36 per 1000 (NICE, 2004).

Depression has a heavy human cost including feelings

of sadness, worthlessness, isolation and an inability to

enjoy life. Depressed people are more likely to take

drugs, be off work or unemployed and kill

themselves. Depression damages individuals,

relationships and families. And it is on the rise

globally.

Electroconvulsive Therapy (ECT) is thought by

some to be one of the fastest ways to relieve the

symptoms of depression and the use of ECT is on the

rise in the UK (Guardian, 2017). It is generally given

when other treatments, e.g. drug therapy, have failed.

Neither ECT nor drug therapy are cures for

depression and both can have significant adverse

side-effects. In view of this it is important that new

safer ways are developed to combat this growing

problem.

Light and smell stimuli have both been used

independently in human studies to achieve positive

psychophysiological benefit. For example, light and

smell have been demonstrated to affect mood and

alleviate depression (for reviews see Oldham and

Ciraulo, 2014; Herz, 2009). Bright Light Therapy

(BLT) is an established treatment for seasonal

affective disorder (SAD) and other mood disorders

(Golden et al, 2005; Pail et al, 2011), having been

successfully used for over 20 years. It has also been

shown to be effective in other kinds of non-seasonal

depression (Naus et al., 2013; Niederhofer and von

Klitzing, 2012) and, in Major Depressive Disorder

(MDD) a randomised, placebo controlled trial

demonstrated that BLT was comparable to

antidepressant medication in effectiveness (Lieverse

et al, 2011). Smell has also been shown to have

effects on mood, stress, anxiety and depression

(Johnson, 2011; Herz, 2009; Ehrlichman & Bastone,

1992; Vernet-Maury et al, 1999; Alaoui-Ishmaili et

al, 1997).

Jacob, T., Warden-Smith, J., Kernot, N. and Burgos, M.

Using Frontal Brain Asymmetry to Control Sensory Treatment of Anxiety and Depression.

DOI: 10.5220/0006471000840088

In Proceedings of the 4th International Conference on Physiological Computing Systems (PhyCS 2017), pages 84-88

ISBN: 978-989-758-268-4

2 BACKGROUND

The concept for this Position paper originates from

two recent papers in which further details about the

subjects, methods and protocols can be found; Dong

and Jacob (2016), Warden-Smith et al. (2017).

2.1 Light and Smell Stimulation

We have designed devices (Figures 1 and 2) to deliver

an integrated stimulation protocol of fluctuating light

and smell with a 60s cycle (Figure 3). A 15min

stimulus session using lemon essential oil and

fluctuating light (0-2500 lux) has positive effects on

mood, lowers blood pressure and heart rate, increases

galvanic skin resistance and rebalances frontal

brainwave asymmetry and we have demonstrated that

this treatment is both anxiolytic and anti-depressive.

The results are presented in detail in Dong and Jacob

(2016) and Warden-Smith et al. (2017). For the

purposes of this present paper it is the possibility of

recording the EEG signal during the light and smell

stimulus protocol that is the prime consideration.

Figure 1: The light and smell stimulus delivery goggles.

The light source in the eyepieces of the goggles is

UV-free light stimulus emitting up to 2500 lux when

in close proximity (2-4 cm) to the eyes. Aroma

vapour of essential oil (lemon) evaporating from a

circular (5mm radius) absorbent cotton pad in a

cartridge in the rear fan pack is delivered to the

nostrils by air blown over the pad driven by an axial

fan (5v,100mA, 0.7 cu.ft/min (0.33l/s), Farnell,

Leeds, UK). Further details in Dong and Jacob

(2016).

Figure 2: Light and smell delivery device.

A free-standing device delivering the same light

and aroma stimuli as described in (a). The subject sits

or lies and the visor is moved to within 5cm of the

face. Odorised air is delivered from a control box

containing fans and an aroma cartridge via a tube to

exit at the base of the visor.

2.2 Frontal Alphawave Asymmetry

EEG alphawave power in the brain has been used as

an index of brain activity. Alphawaves have been

shown to be inversely correlated with brain activity

(Jones, 2007). The brain in its resting state tends to

produce alphawaves. Many studies have demonstra-

ted that a decrease in alphawave activity in the left

frontal hemisphere is associated with an appetitive

response, approach behaviour and positive experien-

ce. Low right frontal alphawave activity is associated

with negative mood and withdrawl behaviour. In

normal subjects, the balance between right and left

frontal alphawave activity (right-left) is positive. In

depression and anxiety the frontal alphawave

asymmetry (FA) becomes reversed (negative) and has

been used as an objective measure of these disorders

(Henriques and Davidson, 1991; Heller et al, 1997;

Davidson, 1998a and 1998b; Thibodeau et al, 2006;

reviewed in Harmon-Jones et al, 2010). FA can

predict future development of anxiety and depression

(Blackhart, Minnix and Kline, 2006) and this

asymmetry has been shown to be a moderately stable

individual difference in adults, irrespective of sex and

history of depression (Allen et al., 2004; Vuga et al.,

2005).

Using Frontal Brain Asymmetry to Control Sensory Treatment of Anxiety and Depression

Figure 3: The light and smell stimulus protocol.

The light and smell stimulus protocol. Diffuse

full-spectrum white light (maximum 2500 lux) is

presented as a triangular wave starting from zero

light, rising to a maximum (2500 lux) linearly over

30s and then declining linearly to zero over 30s.

Simultaneously an airstream containing essential oil

vapour is delivered to the nostrils at two flow rates

(0.17 and 0.33 l/s) to coincide with the up ramp of the

light stimulus. Three cycles are illustrated. The reason

for delivering the stimuli in this manner is to

overcome olfactory adaptation/habituation.

We have demonstrated that 15min stimulation

with fluctuating light and smell stimuli (Fig.3) can

reduce negative FA in those subjects who experience

this asymmetry (see Fig.4; taken from Warden-Smith

et al., 2017). The blue bars in figure 4 indicate the

negative FA experienced by half (32 out of 64) of our

experimental population. During the light and smell

stimulation the negativity of the FA was reduced and

this was maintained after the 15min stimulus period

(at least for 5 mins).

Figure 4: EEG alphawave frontal asymmetry (FA).

The effect of 15min exposure to light and lemon

odour on alpha wave asymmetry. The subjects were

divided into positive (red bars, n=32) and negative FA

(blue bars, n=32) on the basis of their alpha wave

asymmetry (F8-F7). Alpha wave power is expressed

as the average ± standard error (bars) per 10s époque

for 2min before, during and 5min after stimulation.

*p<0.05. Taken from Warden-Smith et al. (2017).

2.3 Real Time Frontal Asymmetry

(FA)

Frontal alphawaves can be measured in the brain

using EEG electrodes and the FA can be determined

in real-time with software (e.g. SPIKE2, Cambridge

Electronic Design, UK) that, by power spectrum

analysis, calculates the power in the alpha frequency

band (8-12Hz) for left and right hemispheres (Fig.5).

These two signal outputs can then be subtracted to

give the FA (green line, Fig.5) which represents the

real-time frontal brain activity with a 5s delay for the

integration period.

Figure 5: Alphawave power in real time.

EEG recording of alphawaves (8-12Hz) from F7

(left frontal; red) and F8 (right frontal; blue) electrode

positions and the subtraction of the two (green). The

alpha power was determined by spectrum analysis

(SPIKE2 software, CED, Cambridge, UK) per 5s

époque. The y-axis is the alpha power (µV

per

epoque) and the x-axis represents time in 5s époques.

Light (2500 lux), smell (vanillin) and light+smell

were applied for 3min.

In figure 5 the difference signal between the alpha

activity in the two frontal hemispheres (FA) is given

by the green line. The FA varies with time and in

normal, healthy subjects is positive on balance

although it can include some negative episodes. The

reverse is true for subjects prone to anxiety and

depression, the balance is negative. How often this

FA signal shifts from positive to negative and vice

versa and what causes it to do so are unknown.

PhyCS 2017 - 4th International Conference on Physiological Computing Systems

3 PROPOSITION

The frontal asymmetry (FA) signal reflects brain

activity in the frontal lobes and is believed to convey

information about psychological state. FA can be

displayed in real-time and could itself be converted

into a feedback signal by transducing it into a tone or

colour thereby relaying the information about the sign

and magnitude of the FA directly back to the subject.

Positive FA is the normal, healthy state and the

desired goal of the light and smell stimulus is to shift

a negative FA pattern back to a positive pattern. We

have demonstrated that a negative FA can be reduced

by 15min light and smell treatment (Fig.4). What

might be achieved by providing a direct and

immediate feedback of the effectiveness of the

stimulation by using the FA signal to control the

stimulus protocol? This might be implemented using

a negative FA reading to increasing the intensity or

the frequency of the stimuli, for example by

delivering a pulse of bright light accompanied by a

pulse of odour when a negative FA period is detected.

3.1 Challenges

1. What are the short-term effects of different

stimulus protocols on the FA sign?

2. Do longer term effects result from short term

changes?

3. How can FA signal be used to control stimulus

protocol to optimise the outcome?

4 CONCLUSIONS

A fluctuating light and smell stimulus protocol has

been shown to have positive effects on mood and

stress-related physiological markers and, in addition,

rebalances frontal brainwave asymmetry towards a

healthy, normal pattern. Using a frontal brainwave

asymmetry feedback paradigm could radically

enhance the effectiveness of such therapy and offer a

real, effective, safe alternative to drugs and

electroconvulsive therapy as a treatment for

depression and anxiety.

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