The bard, William Shakespeare, was a lover of symbolic imagery and flowers and often used flowers to convey meaning between characters and to the audience. Take Romeo & Juliet, for example. Shakespeare uses the imagery of roses (such as represented below) to represent Juliet’s passionate love for Romeo and to emphasize that their love is independent of his family name.

The Elizabethan approach to flower meanings (such as during Shakespeare’s time, the mid-late 1500s) developed into a much more complex, secret language of flowers and social intrigue during the Victorian era (mid-late 1800s), ultimately known as floriography. For example, a yellow rose was a symbol of unfaithfulness during the Elizabethan era, whereas it became a symbol of friendship during the Victorian era.

In today’s world, flowers are often used to represent different causes, such as the poppy (symbolizing remembrance of those who have sacrificed for others) on November 11 for Veterans’ Day in the U.S., or the amaryllis (symbolizing hope and determination) for Huntington’s Disease.

Huntington’s Disease is an autosomal dominant neurodegenerative disease in which the huntingtin gene is mutated. This mutation leads to widespread neuronal loss in the caudate nucleus, which helps regulate voluntary movements and memory.

Although our knowledge of the mechanisms behind this disease has increased, we only have glimpses of the different pieces that eventually weave together into a debilitating and devastating disease that ends with death 15-20 years after onset.

Today, no cure exists, and children of parents who carry the dominant gene have a 50% chance of inheriting the mutated gene (see infographic). Unfortunately, the symptoms of this disease do not usually start appearing until adulthood (average age between 35-44 years), which corresponds to an age by which carriers may have already had children. Genetic testing can be useful for assessing the presence of the gene, but ultimately, onset depends on a variety of factors beyond the genetic mutation.

In the current post, Lee-Anne Morris (pictured below) and a team of scientists from New Zealand to the United Kingdom focused on a specific cognitive deficit associated with Huntington’s disease, goal-directedness. They published their paper on Goal-directed behavior, or the willingness or motivation to engage in cognitive or physical behaviors that are effortful to initiate or sustain, in the Psychonomic Society’s Cognitive, Affective & Behavioral Neuroscience.

Individuals diagnosed with Huntington’s disease often express a suite of symptoms associated with a reduction in goal-directedness. As the researchers highlighted in their paper, one proposed explanation of impaired goal-directedness is apathy, defined as a reduction in motivation to engage in life tasks (or other reward-producing tasks) or attempting to avoid unpleasant experiences.

But individuals with Huntington’s disease also exhibit impulsive behavior in which rapid and premature actions are displayed without appropriate planning.

As Morris shared, “In a nutshell, we investigated which dimensions of the multi-dimensional constructs apathy and impulsivity co-occurred in a cohort of people with Huntington’s disease, a neurodegenerative disease.” Unique to their study, however, was their methodology.

Unique like a Bird-of-Paradise or Venus Fly Trap

First, the research team recruited healthy controls (n = 20) from local research databases and participants with genetically confirmed expansion of the Huntingtin gene (n = 42) receiving care from two specialist clinics in New Zealand. Second, Morris and the team were able to follow up with 95% of the controls and 67% of people with Huntington’s disease one year later. Finally, the researchers “used a data driven approach (principal component analysis) to identify which dimensions loaded onto the same components, and in which direction.”

Is it a Marsh Marigold or a Primrose? It depends on whether you are in North America or England. Using a battery of clinical and behavioral scales with self-reported data on multiple scales of apathy and impulsiveness in addition to motor disease severity and functional capacity, and their data-driven analyses, Morris indicated that they “found three noteworthy components. One of the important findings – the presence of dimensions from both apathy and impulsivity pertaining to goal-directedness, was altered in people with Huntington’s disease compared to controls.” That is, people with Huntington’s disease indicated greater apathy and impulsivity than healthy controls, as expected.

While these results were not unexpected, the researchers chose to address the concepts of convergent operations (assessing the same construct using different operational definitions) and criterion validity (the association between measures that may be investigating the same construct). Morris indicated that “[one] challenge is that fields studying motivation at differing points of its expression (normal, pathological) do not always use the same nomenclature, assessment tools, or even mental process taxonomies.” (By the way, a marsh marigold in North America is not actually a marigold nor is it a primrose.)

An Amaryllis is an Amaryllis – as long as you know it is a genus that includes lilies

Using multiple scales and principal components analysis, Morris and her team demonstrated that in Component 1 (top panel in the figure below), “dimensions of apathy and impulsivity overlap [and] pertain to goal-directedness, including behavioural initiation and perseverance.” More importantly, the purple and blue arrows point in the same direction, indicating a decreased ability for goal-directedness in participants with Huntington’s disease.

Components 2 and 3 showed no overlap in apathy or impulsivity dimensions. In fact, each construct loads in different directions, as indicated by the purple arrows pointing to the right for apathy and the blue arrows pointing to the left for impulsivity. The arrows point in the direction in which the construct is worsening. In component 2, responses of the two groups of participants ranged from careless, social individuals to cautious, socially withdrawn, whereas in component 3, they ranged from emotionally reactive to emotionally blunted, non-reactive.

As shown in the figure below, participants with Huntington’s disease (Component 1, blue line) reported significantly more difficulty planning, initiating, or persevering than controls (Component 1, grey line), while both groups remained consistent in their responses from baseline to 1 year later. No differences were found between the two groups for either Component 2 or Component 3, and scores remained stable over time. If they were Victorian flowers, they would be Greenbells for their stability.

Ultimately, the research team emphasized the importance “that the three components closely resembled three of the five factors from the five factor personality model – an influential model of personality in the psychology literature.” As summarized in the table below, the Five Factor Model of personality proposed by McCrae and Costa in 1985, maps onto the three components identified from the principal components analyses conducted with different measures of apathy and impulsivity.

Component 1, regarding attention, planning, and initiating goal-directed behaviors, parallels the factor of conscientiousness, which relies on brain areas involved in planning and executive thinking. Component 2, involving social behaviors and the degree of carelessness/caution, corresponds to the factor of extraversion. Component 3, involving reactivity and emotional responses to stimuli, is similar to the factor of neuroticism.

Whether an amaryllis or a rose, or clinical neuroscience or psychology, both disciplines “study goal-directedness, impulsive behaviour and motivation, [but] nomenclature between the fields often differs.” However, it is important to remember “that the fields are in fact studying very similar constructs, with deficits evident in a clinical population.” And, all perspectives are critical to finding a cure for this devastating disease.

Featured Psychonomic Society article

Morris, L. A., Manohar, S., Horne, K. L., Paermentier, L., Buchanan, C. M., MacAskill, M. J., … & Le Heron, C. J. (2025). Goal-directedness deficit in Huntington’s disease. Cognitive, Affective, & Behavioral Neuroscience, 1-14. https://doi.org/10.3758/s13415-025-01313-0