Frontotemporal Dementia vs Alzheimer's Disease

Frontotemporal dementia (FTD) and Alzheimer's disease are both progressive dementias, but they usually start at different ages, affect different parts of the brain and cause different early symptoms. The short answer: Alzheimer's usually begins with memory loss in older people, while FTD usually begins with changes in behaviour or language in people in their 40s, 50s or early 60s.

Telling them apart matters. It affects which medicines may help, what families should expect, and whether relatives may want genetic advice.

At a glance

Age

Alzheimer's disease becomes much more common with age and is the most common cause of dementia in older people. FTD tends to start younger: most people are diagnosed between 45 and 65. Among people aged 45 to 64, FTD is about as common as Alzheimer's disease, and it is a leading cause of dementia in people under 60.

First symptoms

In Alzheimer's disease, the earliest sign is usually difficulty learning and remembering new information: forgetting recent conversations, repeating questions, or misplacing things. People often stay socially skilled and may become good at covering up their difficulties.

In FTD, memory is often fairly good at first. Instead, the first changes are in:

• Behaviour and personality (behavioural variant FTD): disinhibition, apathy, loss of empathy, compulsive behaviours or changes in eating.
• Language (primary progressive aphasia): losing the meaning of words, or slow and effortful speech.

People with early FTD usually know the date and where they are, and can keep track of recent events, even if they don't perform well on tests.

One overlap: a language form called logopenic progressive aphasia, which causes word-finding pauses, is usually caused by Alzheimer's disease rather than FTD.

Apathy, mood and behaviour

Both conditions can cause apathy, irritability and poor judgement, especially later on. In Alzheimer's, apathy is usually milder. In FTD it tends to be more pervasive and comes with a striking lack of concern for others. In advanced Alzheimer's, people may become as difficult to manage as people with FTD, so the two can look similar in the later stages.

Why FTD is often misdiagnosed

Because doctors may not expect dementia in someone in their 50s, and because the early signs are behavioural, FTD is often mistaken for depression, bipolar disorder, a midlife crisis, or Alzheimer's disease. Standard memory tests may look nearly normal in early FTD. A specialist assessment, including information from someone who knows the person well and a brain scan, is usually needed.

Genetics

FTD runs in families much more often than Alzheimer's disease. Around 10 to 30% of FTD is caused by a single faulty gene passed down through families, compared with under 1% of Alzheimer's disease. See is frontotemporal dementia hereditary? for more, or our general guide, is dementia hereditary?

Treatment

Neither condition can currently be cured. For Alzheimer's disease, there are medicines that can help with symptoms for a time. These medicines may not help people with FTD, which is one reason an accurate diagnosis matters. In FTD, care focuses on managing behaviour and communication; some antidepressants and, with caution, antipsychotic medicines may help with difficult behaviours.

Progression

Both get worse over time. As FTD spreads through the brain, memory problems and other symptoms develop, and the late stages of FTD and Alzheimer's can look alike. For how FTD typically progresses and what to expect, see the 7 stages of frontotemporal dementia.