Defining: The Difference between Mental Impairment and Developmental Delay

Proper development is the ability to master motor, language, cognitive, emotional, and social skills in a regular environment. Any injury incurred by a child during the gestational period or during infancy can cause irreversible damage to the brain. However since the brain is most supple in a person’s early years, this is also the best time to intervene and effect changes that can improve the situation. Thus, early evaluation and treatment are crucial to a child’s proper development and his ultimate ability to maximize his potential.

Basic Rules of Development

A child’s development hinges on his brain maturation, particularly the production of myelin sheath – the “gray matter” in the brain. A normal, developing child won’t need to be taught motor skills such as walking, crawling, sitting etc. because an adequate production of myelin ripens the brain so that the child will master such activities on his own. Children who are born with brain damage will need outside intervention and stimulation to help them acquire these skills. Sensory stimulation, which is very important in the later stages of development, helps a child access his inner strengths and fulfill his potential. Depriving a child of early intervention and environmental stimulation can lead to a situation where his developmental impairment may be irreversible, especially after the first birthday has passed. While we don’t have the power to directly influence the development of the brain, we do have the ability to impact environmental conditions and the learning process, both of which can ultimately improve brain function. The developmental process is the same for all children; what differs between various children is the rate at which they advance through the process.

Developmental Domains

The basic developmental domains that should be followed up on include: fine and gross motor skills, language (comprehension, expression and communication), and emotional and social behavior.

If a child is behind in only one aspect, mental impairment can be ruled out. A child is considered developmentally delayed when he is significantly behind in at least two aspects, usually the motor and language areas. Most children with developmental delays are actually behind in more than two areas and their delays are accompanied by cognitive dysfunction.

Development generally proceeds in the craniocaudal order –from head down and from the center of the body outward towards its perimeters. Asymmetrical function occurs gradually, with left/right hand dominance determined only from age one and on. However, if a child uses only one hand before he reaches his first birthday, there is room for concern. It is important to take note of an infant’s movements; if his movements are either too monotonous or jerky, this should be checked out.

In the first few months of a child’s life, attention is given to his movements and postures, the steadiness of his sitting, crawling and ability to grasp. Early childhood caregivers (doctors and clinic nurses) will also observe whether a child displays curiosity during playtime as well as basic communicative interaction. From age one, they start looking out for the motor developments of standing and walking, language and play development as well as social behavior and interaction.

Evaluating the Developmentally Delayed Child

It is of utmost importance to get a professional and comprehensive evaluation by qualified experts in the field of childhood development.

The following factors need to be taken into account when performing an evaluation:

• First, it must be ascertained that the child’s vision and hearing are up to par, because defects in these areas are often the chief culprit in developmental delay. 
• It is important to compile a full medical history report that encompasses, in detail, the child’s birth including the prenatal stage, family medical background and general state of health. 
• The child should be taken for a neurological examination, where a thorough assessment will be made on head circumference, muscle tone and other factors that may suggest the possibility of a neurological disorder.
• It must be determined whether the delay is static or progressive. Static delay, which presents in cases of cerebral palsy, cerebral hemorrhage etc., is when a child will be behind in achieving milestones and his progress will proceed at the same, slow rate. When there is progressive delay, such as in the case of a metabolic disease or a tumor, there is regression and deteriorating functionality as the child loses grip on achievements he’d already mastered.
• An additional factor that calls for clarification is whether the delay is being caused by the child’s environment and whether the brain is merely ripening at a slower rate, even though the child’s general faculties may be fully intact.  
• Attention should be paid not only to the lack/presence of achievements but also to the pace at which milestones are reached. A normal child will constantly achieve new milestones, with ever-increasing frequency.

Tests Used to Evaluate Developmental Delay

There are several tests used to evaluate development in early childhood. These tests, such as the Denver Scale, Bailey Scale, Wechsler Test and others, assess the child’s general functioning level and also zoom in on the various domains. Some of these tests provide a DQ (developmental quotient) score, which summarizes the child’s functioning level in comparison to the developmental norm. This score, however, does not necessarily indicate cognitive impairment because with proper stimulation during early childhood, intelligence and function can be enhanced by forming more and more “neural pathways” in the child’s brain.

So when does developmental delay turn into mental impairment?

If a child is behind in several developmental domains and is failing to master age-appropriate achievements in at least some of the domains as he approaches his third birthday, despite receiving abundant stimulation, loving care and support, it is nearly certain that the child will be termed mentally impaired by the time he turns four or five.