Same or Different? - Understanding Developmental Disorders, Dementia, and Mental Ilness

In India, the term “mental health” often seems to evoke a wide range of topics or diagnostic labels. Once, I was called to visit a child at home. I was told that he was intellectually handicapped. When I arrived, I realised that he had cerebral palsy, and that his intelligence appeared intact. Another time, I was referred to an individual wh

o had concerns about her parent’s odd behaviours in the evening. It turned out to be sundown syndrome, as part of a broader pattern of dementia. 

It would obviously be too long for me here to explain all of the diagnostic categories listed in the DSM-5-TR (Diagnostic and Statistical Manual-5 Text Revision) (APA, 2022). I will focus therefore on three main classifications: developmental disorders, dementia (a neurodegenerative condition), and mental illnesses. It is important to remember that these terms are often bandied around in everyday conversation, but they refer to very different kinds of conditions. Confusing them can lead to misunderstanding, stigma, and inappropriate expectations of affected individuals and their families.

Developmental Disorders: Differences that Begin Early

Developmental disorders are conditions that emerge during early childhood, usually before the age of five. They affect how the brain develops. They are:

• Present from early development

• Affect how the individual learns, communicates, relates, or processes information

• Are lifelong, although support needs may change over time

• Are not caused by emotional distress or trauma, although these can coexist

For instance, Autistic Spectrum Disorders (or “autism” for short) affect social communication, sensory processing, and patterns of behaviour. An autistic child does not lose abilities they once had; rather, they develop differently from the start. Importantly, autism is not an illness to be cured. It is a neurodevelopmental difference that requires support, accommodation, and understanding.

Dementia: Loss of Previously Acquired Abilities

In contrast, Dementia is a neurodegenerative condition, not a developmental disorder and not a mental illness. It

• Occurs later in life

• Involves progressive loss of memory, reasoning, language, or daily functioning

• Represents a decline from a previous level of ability

• Is caused by brain disease or injury, not by mood or personality

In other words, a person with dementia once had typical cognitive abilities and is now losing them. This is fundamentally different from autism, where abilities develop along a different trajectory from childhood.

Mental Illness: Conditions that affect Mood, Thought, and Behaviour

Mental illnesses on the other hand, are an entirely different group of conditions. They involve disturbances in mood, thinking, or behaviour that affect daily functioning; and they can occur at any stage of life. Mental illnesses:

• May be episodic or recurrent

• Are often treatable and reversible

• Can be influenced by life events, stress, trauma, biology, or environment

• Do not reflect intellectual ability or developmental level

For example, Depression affects mood, motivation, sleep, appetite, and thinking. A person with depression may struggle to function – but this does not mean that they lack capacity, intelligence, or developmental competence.

Why These Distinctions Matter

Confusing these conditions can cause harm if we have incorrect or inappropriate expectations of the affected individual. For instance, we may

-       Expect an autistic child to “grow out of it”

-       Assume a depressed adult is “regressing”

-       Treat dementia as a mental health problem rather than a neurological one

-       Stigmatize individuals by labelling neurodevelopmental differences as illness

Instead, understanding these differences allows for:

• Appropriate support and accommodations

• Realistic expectations

• More compassionate responses from families, schools, and communities

A Simple Comparison

Aspect	Developmental Disorders	Dementia	Mental Illness
Typical onset	Early childhood	Later adulthood	Any age
Pattern	Different development	Loss of abilities	Changes in mood/thought
Course	Lifelong	Progressive decline	Often treatable
Core issue	Neurodevelopment	Neurodegeneration	Emotional/cognitive distress

Conditions Can Co-Exist

It is also important to remember that an individual may experience two conditions at the same time.

• An autistic person can develop depression.

• A person with dementia can experience anxiety or low mood.

• Mental illness can occur alongside developmental or neurological conditions.

Having one does not exclude the others.

Conclusion

Developmental disorders, dementia, and mental illnesses are not variations of the same thing. They differ in onset, cause, course, and support needs. When we understand these differences, we move away from fear and stigma, and toward respect, appropriate care, and inclusion for people at every stage of life.

At our “Ache Padosi” clinics, Drs Wasker & Lai take a multi-disciplinary and culturally sensitive approach, recognising the realities faced by Indian families, schools, and caregiving systems. We work closely with parents, educators, and caregivers to ensure that individuals receive respectful, evidence-based, and practical support for developmental disorders, neurodegenerative conditions, or emotional/cognitive distress.

If you have concerns about your child’s development, your own mental health, or the cognitive health of an elderly family member, early consultation can make a meaningful difference. Please reach out to us today.