Hypokalemic Autistic Sensory Overload

Hypokalemic Autistic Sensory Overload (HypoASO) is a condition causing distress to autistic people.  Moderately loud sounds, like those around an indoor swimming pool, or shopping mall, can cause an autistic person great irritation, leading to covering their ears, a tantrum, or even self-injurious behaviour (SIB).  The same sensory overload can be caused by light, smell or touch.  

HypoASO is a condition that can be measured and treated.

HypoASO is related to two other conditions Hypokalemic Periodic Paralysis and Hypokalemic Sensory Overstimulation.

HypoASO is an ion-channel disorder triggered by intra/extra cellular concentrations of sodium and potassium.  Calcium may also play a role.  In simple terms, sodium is bad and potassium is good.

Therapy for HypoASO

The therapy for HypoASO is a diet rich in potassium but low in sodium; magnesium will also be beneficial, since it helps maintain the level of potassium.  People with HypoASO need to maintain a high level of potassium in their blood (> 5.0 mmol/L) in order to avoid triggering this ion channel disorder;  this is at the high upper level of the reference range for potassium.   Oral supplements of potassium with magnesium will also prove useful, but need to be spread out throughout the day, for best effect.  Time release tablets should be the most effective.  Very high levels of potassium are dangerous, so care is required.

Testing for HypoASO

Diet should not be changed on a whim.  A simple test can be carried out to check whether the individual is indeed affected by the disorder. 

1.       Find a sound which the person finds disturbing, like a baby crying.

2.       Download a recording of this sound.

3.       Set up a chair in a fixed location in a room with a strong sound system / Hi Fi

4.       Sit the subject in the chair and play the annoying sound at ever greater volume and see at what point the subject reacts strongly (e.g. covers ears)

5.       Repeat the experiment over  a few days to establish a steady base-line volume, at which the subject reacts, (for example volume setting 3, when the amplifier to goes 0-10)

6.       Give the subject an oral potassium supplement (say 250 mg) and wait 20 minutes

7.       Play the annoying sound and measure the volume at which ears are covered.

8.       If the volume is markedly higher than the base-line, you established earlier, then you have established HypoASO

9.       If the subject has an NT sibling, try it on them.  They will most likely show no difference with the potassium and do not have HypoASO