How Are SPD and Anxiety Related?
The condition affects how the brain interprets nerve signals from the various senses–such as touch, taste, hearing smell and sight. Normal events and activities can often trigger sensory overloads in people with SPD and cause panic attacks, stress, and troubling physical symptoms.
Many parents become troubled themselves when they uncover evidence that a child has problems with sensory integration and brain development. SPD can cause kids to throw tantrums, destroy their clothes, refuse to eat certain foods and withdraw from social activities.
The brain receives the same information in people with SPD, but the data don't get properly organized in ways that trigger appropriate responses. It's like a traffic jam in the nervous system, and kids are especially vulnerable as they strive to interpret sensory signals that don't make sense to them.  The disorder can affect anyone, but between 5 percent and 16 percent of children show symptoms of the condition.
Children with SPD tend to show wildly inappropriate behavior. The disorder affects gifted children and those with ADHD, fragile X syndrome and autism at even higher rates.  SPD can be the cause of great stress, so children with the disorder often become extremely anxious about all kinds of things such as routine social interactions, the fit, and texture of their clothes, crowds of people, noises, physical contact, and other sensory stimuli.
Understanding Sensory Processing Disorder
The symptoms of anxiety and SPD are similar, and your child may suffer from both conditions. The exact causes of SPD aren't known, but some studies indicate that birth complications, environmental factors, and genetic predisposition increase the likelihood of your child developing the disorder. 
SPD was formerly called sensory integration dysfunction, and the condition isn't medically recognized as a distinct diagnosis. People with the disorder find common stimuli painful or disturbing. Even the light touch of a garment might chafe the skin. Kids with the condition might bump into things more often than their peers, appear uncoordinated, have difficulties telling where their limbs are and act extremely shy around other children and be unwilling to play or converse. 
The condition is chronic, and there is no known cure. However, most people can overcome the issues to live normal lives by adjusting their expectations. SPD is related to autism. Kids might be disturbed by things most take for granted such as a leaf blower, church bells, and foods with certain textures. Many kids with the condition begin as fussy eaters who often thrown temper tantrums or have complete meltdowns. 
It's believed the root cause is related to hypersensitivity to light and sound, a condition that has a strong hereditary influence. Essentially, that means SPD is more likely to run in families. 
Anxiety-related Complications to Sensory Processing Disorder
Anxiety-related disorders such as phobias, depression and alcohol and drug abuse are common in older children when they also have SPD symptoms. Unfortunately, these disorders are also chronic, and they can trigger more frequent occurrences of other physical ailments such as colds, immune system problems, and bacterial and viral diseases. 
That's why it's so important to deal with SPD and anxiety-related disorders proactively. The conditions can lead to extreme phobias, eating disorders and post-traumatic stress disorder. Left untreated, these sensory disorders can be devastating. However, showing your child simple empathy and planning their daily activities to minimize unexpected stimuli can desensitize your child and help him or her to live normally and productively. 
Dealing with an Anxious Child
Anxiety-producing events can't always be identified in advance, so it's important to provide activities that can help your child manage stress when panic attacks occur. Physical activity often does the job, and concentrating on a favorite fidget toy or game can also generate a calming influence.
The symptoms of both anxiety and SPD include:
- Hypersensitivity to touch and sound
- Fear of crowds
- Balance problems that cause frequent falls
- Skin sensitivity to certain fabrics
- Fidgeting behavior
- Multiple food aversions
- Hearing background noises continually
- Extreme sense of smell
- Inability to moderate behavior such as being over-responsive and under-responsive and developing extreme cravings
- Poor posture
Certain key physical symptoms are common among SPD victims and anxiety-prone patients. A large number of kids with SPD also have symptoms of anxious restlessness. The SPD can cause a child to feel overwhelmed and show symptoms of phobias, obsessive-compulsive disorder, panic attacks, and other disorders. The symptoms of both conditions include: 
- Dilated pupils
- Stomach disorders including cramps, diarrhea, and vomiting
- Shaking and trembling
- Rigid posture
- Excessive sweating
- Bouts of dizziness and disorientation
- Shortness of breath
- Heart palpitations
- Flushed face and neck
- Racing thoughts
Dealing with Your Highly Sensitive Child
Dealing with these mutually aggravating conditions can be a challenge for parents, but taking a proactive approach can help your child blossom. Anxious kids want to feel normal, but they can't always control their feelings. Kids need help with both SPD and anxiety-related disorders, which tend to feed upon each other.
Understanding and empathy are important. As kids learn about their condition, they can respond differently and begin to dial back their inappropriate responses. Avoidance is one solution. Parents can help kids avoid those triggers that generate an attack such as elevators and cramped spaces, large crowds, new foods and unexpected changes to routine.
Parenting a child with anxiety-related disorders and SPD requires a bit more effort than dealing with other children, but the effort can provide big rewards. The extra attention can identify many of the common problems that kids get into as they mature. You must pay more attention to parent an SPD child. That takes conscious thought, planning and identifying potential hazards. As you adjust to the process, it becomes easier to adapt your plans to daily situations.
Strategies for Parenting a Child with SPD and Anxiety
However, none of these things can be completely avoided all the time. Kids need to learn to acclimatize to things out of their comfort zone.
Some of the best practices for parenting a child with SPD and anxiety-related disorders include:
- Recognize your child's strengths to give him or her greater confidence in dealing with sensory overload.
- Find what works to calm your child, but recognize that it is an ongoing process that will need regular updates.
- Reassure your child that he or she is loved, safe and understood.
- Prepare a daily outline of activities to identify potential areas of sensory dangers.
- Eliminate any personal anger or guilt because your child is sensitive to these emotions.
It's important to read extensively about the twin disorders and seek the advice of a physician. You should be aware that before the age of 3, parents get free sensory integration therapy at local early intervention centers. Programs are also usually available for free for children between the ages of 3 and 5 through the Child Find Program, and local Elks club chapters often offer help for evaluation, treatment, and supplies. 
SPD and Anxiety References:
 Spdstar.org: Understanding Sensory Processing Disorder
 Webmd.com: Sensory Processing Disorder: Causes, Symptoms, and Treatment
 Healthline.com: Conditions associated with anxiety
 Lifeskillsforkids.com: Sensory Processing Disorder (SPD) and Anxiety – How are they similar and different?
 Sensory-processing-disorder.com: A Step By Step Guide For SPD Parents: The Seven Steps For Helping Your SPD Child