Differentiating Alzheimer’s, Parkinson’s, and Fronto-Temporal Dementia through Cognitive and Behavioural Profiles

Neuropsychologists are often involved in the process of clarifying dementia diagnoses.

While "dementia" is often used as though it refers to a single condition, it actually describes

a group of disorders with different causes, symptoms, and progressions. Each dementia type

has a distinctive cognitive and behavioural “fingerprint”. Recognising these patterns is

essential not only for accurate diagnosis but also for guiding treatment, planning, and

support for families.

Overview of Major Dementia Types

• Alzheimer’s disease (AD): Memory is typically the first and most noticeable area

  affected. Individuals may forget recent events, repeat questions, or misplace items.

  As the condition progresses, other areas such as language and problem-solving also

  decline.

• Parkinson’s disease dementia (PDD): Often emerges after years of living with

  Parkinson’s. Attention, processing speed, and executive functioning are most

  affected, meaning tasks that require planning, organisation, or quick thinking

  become more difficult.

• Fronto-Temporal dementia (FTD): Unlike Alzheimer’s, FTD can often begin with

  changes in personality, behaviour, or language. Loved ones may notice

  uncharacteristic impulsivity, inappropriate social behaviour, or difficulty finding

  words, long before memory is significantly impaired.

  
  

Other common dementia types include Vascular Dementia, Dementia with Lewy Bodies

(DLB), and mixed dementias. A common misconception is that dementia is simply memory

loss. In reality dementia affects a wide range of functions, including decision-making,

communication, and behaviour. For example, an individual with Alzheimer’s may forget to

pay bills, while someone with Parkinson’s disease dementia may find it increasingly difficult

to manage complex tasks at work, and another person with FTD may display profound

personality changes that disrupt their relationships.

Neuropsychological Assessments for Diagnosis

Neuropsychological assessments allow us to identify the specific profile associated with

each type of dementia. Through a detailed clinical interview and assessment, we evaluate

domains such as processing speed, memory, attention, language, and executive functions to

aid in differentiating between conditions that might otherwise appear similar on the

surface. For example, memory difficulties in Alzheimer’s are quite different in nature from

the slowed thinking seen in Parkinson’s disease dementia or the behavioural disinhibition in

FTD. An accurate diagnosis provides clarity for patients, families, and healthcare teams. It

allows for:

• Targeted treatment approaches – medications may be more effective in certain

  types of dementia than others, and clarifying the necessity of medication may make

  a big difference in quality of life.

• Appropriate family planning – families can make informed decisions about care,

  legal matters, and future living arrangements.

• Better resource allocation – ensuring individuals and carers have access to the right

  services and support networks.

  
  

Cognitive changes have tangible consequences in daily life. Tasks that once seemed simple

and straight forward such as managing finances, cooking safely, or remembering to take

medication can become increasingly challenging. These changes can affect independence

and increase reliance on family or professional caregivers. Families can often feel

overwhelmed when a loved one is diagnosed with dementia. Education and support are

therefore just as important as assessment. Providing caregivers with the tools and

knowledge to support their loved one reduces stress and improves quality of life for

everyone involved.

Not all dementia symptoms are obvious. Subtle signs such as poor judgment, impulsivity, or

changes in social behaviour may be dismissed as stress or ageing, when in fact they can

signal an underlying condition. Greater awareness of these less obvious symptoms can lead

to earlier assessment and intervention.

Early neuropsychological involvement plays a vital role in clarifying diagnoses, supporting

families, and guiding treatment planning. Dementia is a deeply personal journey, affecting

not only the individual but also their loved ones. By identifying the unique cognitive and

behavioural profiles of varying dementia types, we can provide clarity and tailored guidance.

At our clinic, we offer in-depth assessments designed to support diagnosis and care planning with an individual’s loved ones or support team. With early involvement, families are better equipped to navigate the challenges of dementia with confidence and compassion.

Olivia Chan is an early career Clinical Neuropsychology Registrar. She is passionate about

working with individuals across the lifespan and providing evidence-based cognitive

assessments to those with brain-based disorders.